Is It Good to Eat Sugar?

A few “Peat-atarians” – followers of the iconoclastic health writer Ray Peat – have accused us of being too skeptical of fructose. They think we should promote sugar consumption.

Here’s Travis Culp:

I think fructose is only conditionally problematic and that the consumption of it alongside glucose at a time of low liver glycogen is highly advantageous. In fact, I would go so far as to say that (somewhat slowly) drinking a can of soda upon waking (as disgusting as that is) would not result in any real glycation, insulin resistance, elevated TGs etc…. I think it’s beneficial to eat something really sugary upon waking …

Here’s Danny Roddy:

Peat has stated that … fructose … “powerfully” refills glycogen …

I would consider the ability to refill glycogen (minimizing adrenaline & cortisol release) to be an important factor in health …

It’s true that the ability to refill glycogen is essential for health; some genetic glycogen storage disorders are fatal in early childhood. But everyone who lacks a glycogen storage disorder has the ability to refill glycogen from multiple sources. In addition to fructose, glucose sugars and starches refill glycogen, as does milk sugar (a compound of glucose and galactose).

So the question is which combination of dietary sugars (a) is best at refilling glycogen and (b) makes the healthiest diet, all things considered?

Sugar Composition of the Diets

Both Danny and Travis framed their arguments as criticisms of our diet. They are really arguing that a Peat-style sugary diet is healthier than a PHD-style moderate-starch diet.

So before going further, let’s look at the sugar content of the diets we’re comparing.

First, note that PHD is not a zero-fructose diet. As an examination of the PHD Food Plate shows, PHD includes many fructose-containing plant foods – fruits, berries, and vegetables such as beets, onions, carrots, and squashes – plus “pleasure foods” like chocolate.

Also, PHD is not a zero-dairy diet, so for many practitioners it will include some milk sugars which are half galactose and half glucose.

In my diet personally, probably about 55% of carb calories come from starches, 30% from fruits, berries, and sugary vegetables, and 15% from dairy products such as yogurt. In terms of simple sugars, this translates to about 77% glucose, 15% fructose, and 8% galactose.

Not every Perfect Health Dieter will have the same sugar proportions; there is no obligation to consume dairy, and the relative proportions of starchy and sugary plants will vary according to taste. But let’s take mine as characteristic PHD proportions.

In a Peat-style diet, in contrast, the breakdown of sugars is near 50% glucose and 50% fructose.

So we aren’t comparing fructose against glucose, but a 77% glucose 15% fructose diet against a 50% glucose 50% fructose diet.

Why the Focus on Refilling Glycogen?

Why do the defenders of sugar focus on its ability to refill glycogen?

The reason is that fructose is treated by the body as a poison. Dietary fructose is shunted to the liver for disposal by conversion to glycogen, fat, lactate, or pyruvate.

Fructose is treated like a poison because it is dangerous. High doses of fructose have observable harmful effects even in short-term studies. Fructose does no good to the liver while it’s there, in fact fructose combined with polyunsaturated fats very effectively creates liver disease. Fructose in any other organ does harm; for instance, fructose promotes cancer growth.

Given fructose’s rapid disposal, any benefits from fructose have to be attributable to the glycogen or other products it is turned into. If fat, lactate, or pyruvate (a glucose product) provided benefits, dietary fats or starches would do the same, without the risk of fructose toxicity or fats getting stuck in the liver due to choline and methionine deficiency. So if fructose is to have benefits, it has to be via glycogen.

Here, then, is the challenge Peat-atarians face. Fructose has many proven harms. It has only one possible benefit: its ability to help re-fill liver glycogen. Peat-atarians have to show two things:

  1. That a diet with Peat-like sugar proportions – roughly 50% fructose, 50% glucose –is better than a diet with PHD-like sugar proportions – 15% fructose, 8% galactose, 77% glucose – at refilling liver glycogen.
  2. That better re-filling of liver glycogen improves the healthfulness of the diet.

How Do Sugars Perform at Refilling Glycogen?

Danny provides no citations for his claim that fructose “powerfully” refills glycogen. But Danny’s commenters help him out.

Daz, drawing upon a New York Times report, offers two studies [1] [2]. Cliff offers several more [3] [4]. Let’s see what these tell us.

The first study, “Fructose and galactose enhance postexercise human liver glycogen synthesis” [1], looks at athletes depleted of liver glycogen by intense cycling, and assessed the effectiveness of three sugar drinks at replenishing liver glycogen. The three drinks were:

  • 2/3 maltodextrin, 1/3 fructose;
  • 2/3 maltodextrin, 1/3 glucose;
  • 2/3 maltodextrin, 1/3 galactose.

Maltodextrin digests to glucose, so all three drinks are majority glucose. The athletes drink 275 calories of these drinks per hour for 6.5 hours after exercise. Galactose is non-toxic, but like fructose tends to be taken up by the liver.

Liver glycogen was measured every two hours with carbon-13 magnetic resonance imaging. Here were the results:

So 67% glucose / 33% galactose did the best, 67% glucose 33% fructose was close behind, and 100% glucose lagged.

Why does the 100% glucose drink underperform? One reason is that fructose and galactose, but not glucose, are preferentially targeted to the liver:

A factor of potentially larger magnitude in enhancing liver glycogen synthesis is the differential postabsorptive fates of fructose and glucose. Glucose is a relatively poor direct substrate for liver glycogen synthesis (24,27). Much of it is released from the liver into the systemic circulation to be stored as muscle glycogen (3,7). In contrast, fructose is primarily taken up by the liver … [1]

The second paper, “Superior endurance performance with ingestion of multiple transportable carbohydrates” [2], did not measure liver glycogen replenishment; instead, it gave its cyclists sugary drinks every 15 minutes throughout an intense 2-hr cycling test, and compared performance. Three different drinks were used: a 67% glucose 33% fructose drink, a 100% glucose drink, and a water-only control group. Performance was best with the 67% glucose 33% fructose drink, intermediate with the glucose drink, and worst with the water drink. The results suggest that the 67% glucose 33% fructose drink was better for liver glycogen replenishment, and that liver glycogen replenishment aided the cyclists’ performance.

The third paper, “Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis” [3], isn’t available to me electronically, so we’ll have to work from the abstract. It looked at muscle glycogen, measured using biopsies (ouch!), rather than liver glycogen.

It first assessed the effect of different amounts of glucose. It found that 0.7 g/kg body weight of glucose given every 2 hours would maximize the rate of muscle glycogen synthesis. For an 80 kg man, that works out to 56 g or 224 calories of glucose per two-hour period, or 112 calories per hour. Above this amount, the rate of muscle glycogen synthesis is unchanged.

It then compared three formulations at this same 0.7 g/kg body weight dose: 100% glucose, 100% sucrose (50% glucose, 50% fructose), and 100% fructose. Muscle glycogen synthesis rates were:

  • 5.8 mmol/kg/hr with 100% glucose
  • 6.2 mmol/kg/hr with 50% glucose, 50% fructose
  • 3.2 mmol/kg/hr with 100% fructose

If we fit a quadratic curve to these points, it predicts a peak rate of glycogen synthesis with 70% glucose, 30% fructose:

Athletes Agree: More Glucose Than Fructose

Of course, endurance athletes know that it’s beneficial to replenish glycogen during endurance events like marathons and triathlons.

Some authorities, including Tim Noakes, an exercise physiologist who has run over 70 marathons, believe that liver glycogen rather than muscle glycogen is the gating factor in marathon performance. From “The Science of Carbohydrate Loading” by David Peterson:

Remember also that muscle glycogen is committed to be used by muscle and cannot assist in maintaining blood sugar levels. Therefore should no additional carbohydrate be ingested during prolonged exercise, the task of maintaining blood glucose levels rests firmly on the liver’s glycogen stores and gluconeogenesis (the manufacturing of glucose from plasma amino acids). Oxidation of blood glucose at 70-80% VO2 max is about 1.0 g/min or about 60 g/hour. Therefore it can be predicted that even with full glycogen stores, a less conditioned athlete’s liver will be depleted of its carbohydrate within an hour and three quarters of continuous moderate intensity exercise. (Interestingly, the daily carbohydrate requirements of the brain and nervous system alone are enough to deplete the liver glycogen stores within 24 hours.) Once liver glycogen levels begin to drop and exercise continues the body becomes increasingly hypoglycemic (low blood sugar) mainly because blood glucose is depleted faster than it is replaced by gluconeogenesis. Professor Tim Noakes considers liver glycogen depletion and subsequent hypoglycemia to be the primary factors affecting fatigue and performance during extended duration races and especially in instances where muscle glycogen levels are low as well.

So marathoners and other endurance athletes will want to replenish liver glycogen as rapidly as possible during a race. What mix of sugars do they use?

The popular product is carbohydrate gels that can be swallowed at the same time water is taken. Here are the top carbohydrate gels sold on Amazon:

So the sugar mix ranges from 67% glucose to 100% glucose. No product uses 50% fructose.

Presumably, athletes have done a great deal of personal experimentation and know that these ratios do, indeed, optimize the speed of glycogen replenishment.

When athletes have no need for speed, as when they are carb loading before a marathon, then they eat starches like pasta and bread, not sugar. So to maximize total glycogen status, regardless of speed of filling, a carb mix close to 100% glucose works just fine.

Glycemic Control

The fourth paper, “Acute fructose administration decreases the glycemic response to an oral glucose tolerance test in normal adults” [4], is about how a bit of fructose affects the glycemic response to an oral glucose tolerance test.

It showed that a 9% fructose 91% glucose test (7.5 g fructose, 75 g glucose) produced a lower glucose area under the curve and higher insulin response than a 100% glucose test. Here’s the glucose response:

In general higher insulin and lower glucose is healthier than the reverse, so this is considered an improvement.

Summary of the Data

What these papers show is:

  • Glycogen replenishment proceeds the fastest with a mix of sugars consisting of about 70% glucose and 30% fructose or galactose.
  • Although this wasn’t tested, we can guess that a mix of fructose and galactose would be more effective than fructose alone, since it seems that utilizing multiple carbohydrate pathways is what drives the speedier glycogen replenishment. So the fastest glycogen replenishment might occur with something like 70% glucose 15% fructose 15% galactose.
  • Muscle glycogen replenishment is maximized with a carbohydrate intake of 100 calories per hour.
  • Athletes agree with the research, using carb gel packs that contain typically 30-40 g carbs with a composition of 67% to 100% glucose, 0% to 33% fructose.
  • Glycemic response to a large dose of carbohydrate may be improved by eating a 9% fructose 91% glucose mix.

From these data, I infer that for glycogen replenishment in liver or muscle, a PHD-style carb mix of 77% glucose, 15% fructose, 8% galactose is probably equal or superior to a Peat-style carb mix of 50% glucose, 50% fructose.


For athletes in the midst of a race, or in need of rapid recovery for a second race on the same day, speedy glycogen replenishment may be the endpoint to optimize. If so, they should eat a sugar drink composed of roughly 70% glucose and 30% fructose and galactose.

This is closer to PHD diet ratios than to Danny Roddy’s recommendation of orange juice or Travis Culp’s recommendation of soda!

But for others, speed of glycogen replenishment is hardly likely to be the parameter to optimize. There are unlikely to be significant benefits for non-athletes from replenishing glycogen 6.5% faster, as was found in the muscle glycogen study [3].

Speedier glycogen replenishment is almost the only known benefit to fructose consumption. It’s possible that low fructose doses, about 9% of carb calories (perhaps 2-3% of total calories), may improve glycemic control. This is a lower fructose fraction than is found in PHD, and far below the fructose fraction recommended by Danny and Travis.

Given the known risks of fructose consumption, especially with chronic intake at high doses or in conjunction with polyunsaturated fats, it seems prudent to err on the low side. It seems to me that the Peat-atarians have failed to provide any evidence at all in favor of a higher fructose intake than is provided by the fruits, berries, and sugary vegetables recommended by the Perfect Health Diet, save for athletes in the midst of a race or post-race recovery.


[1] Décombaz J et al. Fructose and galactose enhance postexercise human liver glycogen synthesis. Med Sci Sports Exerc. 2011 Oct;43(10):1964-71.

[2] Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc. 2008 Feb;40(2):275-81.

[3] Blom PC et al. Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis. Med Sci Sports Exerc. 1987 Oct;19(5):491-6.

[4] Moore MC et al. Acute fructose administration decreases the glycemic response to an oral glucose tolerance test in normal adults. J Clin Endocrinol Metab. 2000 Dec;85(12):4515-9.

Leave a comment ?


  1. What about the Glucose Paradox PJ?
    “Evidence has mounted that under physiological conditions glucose utilization by the liver is rather limited and that it is in fact a poor precursor for glycogen and fatty acids(much inferior to gluconeogenic substrate such as fructose, lactate or glycerol)”
    “The paradox is that the large amount of glycogen (10%) in the liver cannot be explained by its relatively minimal glucose absorption.”

    Making glycogen from lactate or glycerol is anti-thyroid in peats opinion.

  2. Thyroid increases thermogenesis, is that a toxin too?

  3. Hi cliff,

    There’s agreement that liver glycogen gets synthesized after glucose ingestion. The paradox is over how. See this quote from the paper’s conclusion:

    it should be emphasized that we do not challenge the fact that in the intact organism a major fraction of dietary glucose is ultimately converted into liver glycogen

    The claim that processes involving lactate or glycerol are anti-thyroid needs documentation. It’s hard to credit, especially if these are normal physiological substrates for liver glycogen synthesis.

  4. Paul,

    My idea was based upon the chronic deprivation of vital nutrients, as well as chronic exposure to plant toxins such as gluten, that brought about such a hormonal disruption that necessitated the supplementation of refined, but not toxic, foods (i.e. ice cream and orange juice) that can help attenuate the hormonal problem without adding excess stress to create another problem. Though I understand it may resemble a pharmaceutical approach, I like to view this as the approach taken by traditional tribes, specifically in the application of refined wisdom–similar to how Weston Price described cultures that had pristine dental health as a result of their accumulated wisdom, and subsequent application/refinement of it.

    To be slightly clearer, I’m sure you’ve taken notice of metabolic flexibility graphs–those comparing the macronutrient partitioning abilities of obese individuals compared to metabolically healthy ones. It is shown there that obese people tend to burn an increased ratio of carbs to fat. This line of thought carries through to PHD carb recommendations, where the guidelines state an general recommendation of 400-600 carb calories. Now according to my logic, if you convinced a severely obese person to follow this mantra they would have to produce additional glucocorticoids compared to a leaner individual (adjusting for total weight/height,etc.) due to the disruption of their metabolic milieu (hormones and all). In their case orange juice “supplementation” would be more beneficial, and as their weight–and subsequent metabolic status–improved, we could taper down the “supplements”.

  5. I would like to hear your opinion on a diet that is high carbohydrate and fruit based with very very very very low levels of PUFA. How toxic do you consider fructose in the near total absence of PUFA?

    They say human gut morphology is based on the fact that we evolved from frugivores, that is, frugivory adapts apes to soft calorie dense foods. When we discovered hunting and cooking, we took advantage of this pre-existing adaptation and further evolved in that direction thus increasing the size of the small intestine and shortening the length of the colon. From the standpoint of human geographic dispersal, moving to starch and fat based diets makes very good sense as these are much easier to consume in northern climates and/or store not to mention being much lower volume per calorie. Considering the importance of calcium:phosphorus ratios and the interesting coincidence that Peat’s anti-inflammatory amino acids are most abundant in eggs and shellfish; I’m starting to think that humans probably initially evolved in coastal forests with a fruit dominant diet supplemented by stealing eggs, shucking bivalves, and the odd insect or anthropod with fiber coming from leafy greens. Dairy, as such, provides a convenient way to replicate all these conditions which is why I believe Peat supports it. Without dairy, you’d need to eat clams, oysters, and probably 4lbs of leafy greens every day in addition to fruit and tubers.

  6. Hi Paul –

    I have listened to five of your podcasts this week – thank you!! On fructose and PUFA’s. I have been giving my children their fermented cod liver oil shots with apple juice and I poach their salmon in apple juice. Am I poisoning them?? 😉 All kidding aside, if it is causing a harmful oxidation effect, I will stop it and find another way.

    Thanks for your help! Pam

  7. On a semi-related note, babies don’t even have GLUT5 transporters, meaning colics are mostly caused by fructose.

    Normal people generally do not absorb fructose great:
    Small-intestinal absorption of fructose was investigated in healthy human subjects by sequential breath-hydrogen measurements. Fifty-eight percent of 103 subjects produced greater than 20 microL H2/L after consuming 50 g pure fructose in water. About half of those who absorbed fructose incompletely (incomplete absorbers) had abdominal symptoms. Malabsorption of medium doses of pure fructose may therefore be common in man. When 25 g pure fructose was consumed, only 19% of 21 poor absorbers (of 50 g fructose) still produced excess breath H2. When glucose was taken with fructose, the frequency and amount of excessive breath H2 was substantially reduced.
    This is typical soda scenario, its less ‘fruit scenario’ but could be easily done by anybody consuming fructose rich, glucose poor fruit.

    Its known that glucose helps it by some hypothetical cotransport, but that brings old question – how good is this combo for the liver. But we know that, as Pual noted, at least in CM deficiency state its not good. Deficiency of choline is more or less regular thing and vegetarians are probably deficient in methionin too:

    Rats are probably not a good model because their diurnal change of GLUT5 expression shows how important fructose might be for them: Diurnal rhythm consists of an anticipatory fourfold induction of intestinal GLUT5 mRNA and protein expression occurring 3–4 h before the onset of peak feeding. This doesn’t happen in humans to that extent and when it does its not in advance like with rats, unless you are T2 diabetic in which case, for some reason, GLUT5 is over-expressed several fold in the gut.

    As a small nitpick, from the review presented at
    we see there are other potential uses of fructose in the body – sperm motility.

    My personal opinion: take apple a day literally .

  8. Hi Lenny,

    I think the obese burn more carbs than the non-obese because (a) both populations are eating excess carbs, ~50% of calories, and (b) the carb-to-fat conversion pathways are somewhat blocked in the obese.

    I don’t think the proper response to this is to continue to eat an excess of carbs.

    Hi Joe,

    Toxicity depends on quantity. Low doses of fructose in the presence of PUFA are toxic to the liver; in the absence of PUFA, high doses of fructose are toxic to the body. Exactly where “high” is, I’m not sure, but I don’t see much benefit to fructose consumption, so it’s easy for me to recommend getting it only from whole foods.

    Hi Pam,

    I would recommend switching to another sweetener, like rice syrup. Even honey would be better.

    Hi maj,

    Thanks, interesting comments all.

  9. @maj- 90% of fruit are a 50/50% ratio, apples are the exception not the rule. The children did fine on grape juice.

  10. @cliff

    That isn’t really important since the parole isn’t “an grape a day keeps doctor away”.

    Apples were purchased by 80 percent of consumers in 2006, according to The Packer’s Fresh Trends.

    with the most consumed fruit being banana.

    Fruit is massively consumed all around because everybody think they are abnormally healthy. And they are, if you eat them occasionally and don’t drink fruit juices every day.

  11. @majkinetor

    Thanks for letting me know your opinion. I’ll stick with the facts.

  12. Sucrose substitution in prevention and reversal of the fall in metabolic rate accompanying hypocaloric diets

    Hypocaloric diets cause a fall in resting metabolic rate that interferes with weight loss. To evaluate the mechanisms underlying this phenomenon, resting metabolic rate was measured sequentially in six healthy obese women on a weight maintenance diet (more than 2,300 kilocalories), after 15 days of an 800 kilocalories carbohydrate-free diet, and after isocaloric sucrose replacement for an additional 15 days. The carbohydrate-free diet produced a 21 percent decline in resting metabolic rate (p <0.005) as well as a decrease in circulating triiodothyronine (41 percent, p <0.02) and insulin (38 percent, p p <0.1). However, when sucrose was substituted, resting metabolic rate rose toward baseline values even though total caloric intake was unchanged and weight loss continued. The sucrose-induced rise in resting metabolic rate was accompanied by a rise in serum triiodothyronine values, but not plasma insulin or norepinephrine concentrations. Throughout, changes in resting metabolic rate correlated with changes in serum triiodothyronine levels (r = 0.701, p <0.01). In four obese women, a hypocaloric sucrose diet was given at the outset for 15 days. The fall in both resting metabolic rate and triiodothyronine concentration was markedly reduced as compared with values during the carbohydrate-free diet. It is concluded that carbohydrate restriction plays an important role in mediating the fall in resting metabolic rate during hypocaloric feeding. This effect may, at least in part, be related to changes in circulating triiodothyronine levels. Incorporation of carbohydrate in diet regimens may, therefore, minimize the thermic adaptation to weight loss.

  13. Hi cliff,

    Thanks for the paper, it’s useful for my obesity thesis.

    However, the fall in T3 and metabolic rate is due to carbohydrate deficiency and the need to conserve glucose. I’ve blogged repeatedly about that. Starch does just as well as sucrose at preventing it.

  14. Paul,

    Sorry to beat a dead horse, but according to Peat, metabolic disturbance–chronic hyperglycemia–is due to elevated cortisol. So while your suggestion is reduce overall carb levels and supplant the ones you do eat with starch, Peat suggests consuming sugar, which targets the liver more so than pure starch–as your article suggests. The latter suggestion reduces cortisol by saturating liver stores while reducing insulin (due to half fructose/half glucose), meanwhile pure starch would have to be dealt with solely by insulin, and there would be less of a tendency to saturate liver glycogen, subsequently leading increased glucocorticoids and a reduction in thyroid functioning.

    According to Danny Roddy, Dr. Kharrazian also promotes a constant flow of glucose for his IR patients–

    I understand your line of reasoning throughout all this, but after being exposed to certain anecdotes, again from Danny Roddy’s recent post–Where a woman expresses improvement when she “started eating more carbs in the form of fruits and orange juice (was already eating a fair share of “safe starches”).”

    I think the HPA axis and thyroid functioning needs to be assessed before any “perfect health” diet is prescribed–adding another possibility towards using diet to diagnose pathology, besides pro/eukaryotic infections that you suggest.

  15. @ Lenny

    That is a great synopsis that I was trying to refer to in my previous comments. Not all of us are so gifted, lol. This is why I feel a weekend spent together by phone or visitation between Paul and Ray would really be useful for both sides. They both approach some similar problems with different ideas that I feel marry well when taken all together. Because Peat’s work has a focus on stress and it’s effects on the organism and cellular energy production I tend to side with Peat on many things. I feel Paul’s approach marries well because toxins and infections are primary sources of environmental stressors. Stress is at the center of it all and the associated cascades can spiral out of control in different ways for each individual. I am currently attempting to synthesize the ideas of both and incorporating Robert Sapolsky’s ideas about stress into my own approach to “evolutionary” lifestyle practices. Lastly, both Paul and Ray stress the importance of thyroid function but both have different takes on the “optimization” of that pathway. I feel too much of the “paleosphere” tends to view the organism from the viewpoint of scarcity. Peat attempts to view the organism from the viewpoint of abundance. Both viewpoints yield similar approaches but with slightly different interpretations of the true state of the organism.

    @ Paul

    Why don’t you send a copy of your book to Ray and have him review it? Then ask if he would be interested in a guest post concerning some of his points of contention. I think the both of you can learn a lot from each other and without having to do so much research on subject matter for which you do not have time. I think your blog does a tremendous job of bringing many lines of research together but there is too much out there for just one man/couple. Also, it tends to irritate me that you still associate your nutritional approach to “Paleo” and feel an appropriate change to “Evolutionary” is much needed, mainly because there are too many “Paleo” die-hards who are too dogmatic and also because the current mainstream interpretation of “Paleo” seems to gravitate towards the dogmatic approaches.

  16. Paul,
    Based on your answer I find it hard to believe that you and Peat are really on opposite sides. The main difference is in what fuel source you believe to be optimal but besides that, there seems to be little true disagreement. Seeing as you support fructose consumption from whole foods and are against the combination of fructose with PUFA; well, this is the same as what Peat prescribes.

    I’d like to suggest that Peat’s diet may be thought of as an evolutionarily earlier form of your diet. That is that the human diet may have consisted mostly of fruit and coastal animal protein at first and once migrating onto the plains and northern climates we changed our staples to fatty meat and root vegetables. In other words, there is the Northern/Plains diet (PHD), and the Southern/Coastal diet (Peat).

    In any case, I understand your aversion to fructose in light of all the studies documenting its ill effects but considering some of the anecdotes seen from people on high fruit protocols, it does seem that there is more to this story than meets the eye.

  17. Paul, this discussion gets to the crux of what I do not understand about the Perfect Health Diet. You are speaking as if refilling liver glycogen is a good thing, and it undoubtedly is, because mood is so much better when there is sufficient liver glycogen because then the brain is confident of its power supply. Also, you acknowledge that safe starch would eventually replenish liver glycogen after muscle glycogen is topped off. So why not eat enough starch to replenish liver glycogen? It is not so difficult to figure out how much that would be. Have some sugar, feel what replenished liver glycogen is like, then titrate safe starch gradually meal-by-meal to get the same effect. When I do it, and I am not an athlete, I get 260 grams of non-fiber carb per day, which is considerably more than you usually recommend. Have you tried this experiment and found the result unsatisfactory in some way?

  18. Hi Jim,

    It’s an excellent question. I’m not persuaded that it’s a desirable thing to keep liver glycogen filled at all times, but for some health conditions it may be good to tend that way, like hypothyroidism. There may also be a case to be made for intermittent / occasional high-carb feeding.

    260 g is 40-50% of energy, which is close to how most people eat.

  19. Can’t wait for the obesity thesis. I still don’t know how you can respond to every comment, I get tired just reading them.

  20. Hi James,

    I haven’t been able to keep up either. The Q&A thread has gotten away from me, and a few other threads.

  21. Paul, the high-sucrose fed mice had lower fasting glucose and insulin, as well as being more insulin-sensitive (see ITT). But the point was that this is by far the longest-term animal study, and also one of the most high-quality IMHO, on the chronic effects of high-sucrose diets, and it doesn’t verify any of the supposedly negative metabolic effects of sugar found by shorter-term studies and studies using pure fructose, or using sucrose in combination with high PUFA diets. So this provides stronger evidence that in the context of life-long consumption, eating lots of sugar is not a problem, than the plethora of fructose-overfeeding experiments provides to the contrary.

    For positive effects of fructose you have to actually read some of Peats writing, particularly his November 2011 newsletter on sugar. But just one more question, if fructose is a “poison”, why why would it be one of the substances we find most intuitively rewarding to ingest? Sugar, unlike foods that truly can be poisonous such as alchohol, raw vegetables, raw meats and legumes, is one of the few things you never have to learn to appreciate, everyone is just born with a strong taste for it. I can’t see this being the case with any other substance that is a poison for us.

  22. Colldén

    Raw beef tastes amazing (grass fed). And is very safe. You could check out the raw paleo forum, for more information and journals from long term raw meat eaters, if you don’t believe me. I would think twice before putting raw meat in the same category as alcohol.

  23. Paul,

    I am looking for a protein powder with maltodextrin in it. Do you know of any brand? I have been looling at the only one I have found so far is one with soy and I dont want that either. I may have to find one and just add dextrose? I am a bodybuilder.

  24. Hi Jerry,

    Yes, why not add dextrose yourself or eat rice syrup with it?

  25. Thanks Paul.

  26. Jerry, I switched to maltodextrin (I got it from truenutrition) to reduce food reward and for faster stomach emptying time. Malto’s lower osmolality (than dextrose) lets it move out of the stomach quicker. It’s probably a difference that makes no difference though …

    One scarfs down protein shakes so quickly that it doesn’t make sense to flavor them much.

    I can definitely see a case for dextrose though, if you savor your shake during a workout I would guess it would reinforce working out in the future.

  27. As someone following the PHD with a good dash of Peat, I really enjoy this post and the comments. Thank you Paul.

    Using athletes as evidence is clever, but keep in mind that Tim Nokes is the first to claim that the composition of sports nutrition is supply driven (by the Industry), not based on demand or the need of the athlete. Well, to be fair his point is made about drinks (and Getorade etc. is not primarily targeted at athletes, but those who want to identify as such), but as far as gels go, the story might be different – no sane truck driver or high school kid would ingest that stuff voluntarily. So since Paul is using gels as an example, it may actually be that the lab testing of athletes is not just for show. But as others have pointed out – if you run for two hours, high fructose might cause GI issues for people who would not have a problem with it while sedentary.

    Okay, so I am the woman, the “anecdote”, in Danny Roddy´s recent post referred to by lenny above, so I will try to give some of my latest thinking as for why I did better on adding some “Peat” diet interventions to the PHD mix, and why I think I am not the only one. I am still learning, so I do not claim to have found any truths, and forgive me for a messy presentation, but here you go:

    Paul says that “I’m not persuaded that it’s a desirable thing to keep liver glycogen filled at all times, but for some health conditions it may be good to tend that way, like hypothyroidism.” Well, according to Chris Kresser, 13 of the top 50 selling US drugs are either directly or indirectly related to hypothyroidism. If going by either the low body temperature/low pulse diagnostic, and/or some kind of pattern on the serum tests (Anti-TG, TPO, TSH, free T-3, free T4, total T3, total T4), we are talking a significant proportion of the population, especially women, being hypothyroid in some form.

    There seems to be a correlation between hypothyroidism and estrogen (Peat certainly thinks so). Following a Peat like theory of the immune system (Polly Matziger, Jamie Cunliffe), high anti-bodies to the thyroid might actually be an attempt to clean up an estrogen mess in the tissue. There seems to be a sex difference in carbohydrate metabolism in general, both in muscle tissues and in the liver ” (….) lower hepatic glucose production for women compared with men” ( Women tend to utilize free fatty acids more than men during moderate endurance exercise. The difference seems to be estrogen related, which influence fuel selection towards free fatty acids. Men given estrogen supplements, change their fuel source selection during rest and endurance exercise ( But the estrogen induced pathway might not be the most favourable state, and for slim people, often problematic. Judging from anecdotes, I think Danny has mentioned this, and I certainly have, some people seem to experience lean mass increase on Peat´s diet and reduction in body fat, probably because one is able to break the more catabolic type of metabolism. Back to the estrogen – a history of oral contraceptives is probably a red flag. Further, a crash in T3 from very low carb, can cause progresterone production to plummet, which again leads to an estrogen excess. With an increased exposure to estrogen in the environment in general (plastic etc.) and maybe by a less fortunate response to very low carb, men are at risk too. In a state of estrogen excess, the liver is busy detoxifying, maybe a reason for why the glycogen in the liver is not used efficiently. Many with low T3 have a conversion problem from T4 in the liver (80% of T3 is converted from T4 in the liver and kidneys – only a small portion is coming from the thyroid gland).

    Is it a good idea to NOT try to fill the liver glycogen in such a pattern? For those who have lived with the consequences of low T3 (adrenaline rush, waking up in the middle of the night, fatigue, tendency to orange-yellowish color i the face etc.), and had improvements on a more Peat like diet, I do not think so.

    And lastly, I will not say the feminist argument, but rather the “where you stand depends on where you sit argument” – most of (or all?) the lowish carb Paleo gurus seems to be men. Peat, as someone with a more typical “female” hypothyroid (and high estrogen?) pattern seems to have a lot to offer many with a similar pattern, many being women.

  28. Hi Paul!

    What is your theory on how the Kitavans consume mostly carbohydrate(glucose/fructose) but don’t seem to exhibit any toxic effect from constantly keeping glycogen stores high or over-full? Are they continuously depleting stored glycogen through their lifestyle and then possess the ability to refill at will? Does extra glucose in the body only become toxic through a sedentary lifestyle?

    All of their carbs are “safe starches” and thus contain a high water content. I wonder if they are even consuming as much glucose as some suspect from just looking at the macro-nutrient ratio. (Just hypothesizing from listening to you talk about the glucose availability from cooked white rice was very low compared to the amount.)

    Thanks for your time.

  29. IS anyone really going to believe that when a person ingests over 1 POUND DRY! of pure sugar over 6 hours that they only achieve a 20-60% refilling of liver glycogen? ANd that is directly AFTER emptying the liver of glycogen through strenuous exercise? (When lactic acid levels are THROUGH THE ROOF and therefore glycogen creation by the liver is ultra-elevated)?

    Does anyone else find this as preposterous as I do?

  30. @Jerry,

    SAN has some starch product (SAN ELEMENT) similar to waxy maize, but made from potato starch what you could add to your protein.
    Absolutely pure and tasteless, if it is that what you want and suppossedly faster acting then dextrose/malto.

    But honestly, I never saw a difference and are doing as well with just whey hydrolysate+bcaa taken ~20-30 min. before the workout.

  31. “That is, View the MathML source mice gained more weight on high-fat diets without consuming more calories than View the MathML source mice. The increase in FE was related to adipocyte hyperplasia in View the MathML source mice on high-fat diets. Fat-induced obesity in View the MathML source mice was unrelated to adrenal cortical activity. In the absence of fat, sucrose produced a decreased in FE in both strains. Animals fed a low-fat, high-sucrose (LH) diet were actually leaner than animals fed a high—complex-carbohydrate diet. Fat was also found to be the critical stimulus for hyperglycemia and hyperinsulinemia in View the MathML source mice. In the absence of fat, sucrose had no effect on plasma glucose or insulin. These data clearly show that across these two strains of mice, genetic differences in the metabolic response to fat are more important in the development of obesity and diabetes than the increased caloric content of a high-fat diet.”

    Pretty interesting that the sucrose rats were leaner than the complex carbohydrate controls.

  32. ET, you bring up an important issue – the impact of unbalanced sex hormones on health, especially women’s, and what dietary strategy is best for correction. It’s a subject that gets too little attention by the diet bloggers, who, as you note, are almost all men. That’s not to say they don’t care about women’s sex hormones. I think one of the reasons Peat is so popular and has devoted fans is because he’s one of the only science-based bloggers paying meaningful attention to sex hormones and how to correct them via diet. BHRT is just not where a lot of us want to go, but there is precious little guidance in the Paleosphere on how to balance female sex hormones. It can make one feel quite desperate.

    And I think you’re right that the birth control pill has put a lot of us in a bad way. We’d be very fortunate if Paul would give us his thoughts about it. There are a few Qs in the Q&A section about low testosterone in young women, so I think there’s quite an audience for this topic.

  33. Hi JW,

    I fully agree that hormonal disruption is a serious issue, and that there is a paucity of information available for how to fix it. I wish I had the knowledge to remedy that problem, but alas, I don’t.

    It’s not obvious to me that anyone has that knowledge. From what I know of biology, it’s extremely difficult to interpret hormonal levels.

    I tend to favor approaching such problems indirectly, fixing diet, nutrition, and infections, then giving the body time to heal. Experience will have to show us whether that is sufficient.

    Best, Paul

  34. Hi Dr. Jaminet!

    Three times a week I go to a 20 minute spinning class.

    To replenish my glycogen levels, right after I finish class I take a mix of powdered whey (72 grams of protein and 360 calories) with a mix of powdered carbohydrates (100 grams of carbohydrates and 400 calories) dissolved in water.

    My carbohydrate mix – Now’s Carbo Gain – ingredient is 100% pure maltodrextin from corn, a bad carbohydrate according to PHD.

    Am I compromising my health from consuming the Carbo Gain?

    If so can you suggest other carbohydrate for my post workout feeding?



  35. Hi palo,

    It seems an awful lot of calories for a 20 minute spinning class. Why not eat a meal of real food instead of powdered macronutrients? Then you’ll get micronutrients and other useful things along with the macronutrients.

  36. Hi Paul,

    Sorry if this is the wrong venue to ask about another of Peat’s prescriptions, but here goes…

    I was wondering about the calcium recommendations he suggests. Supposedly Peat says parathyroid hormone is inflammatory, so increasing calcium intake (and therefore serum calcium) will help reduce it. So here are my two questions about this: 1) according to , increased calcium can cause problems with zinc absorption and obviously many other problems as a direct consequence, so where does the dose of calcium do more harm than benefit?and is it dependent upon diet vs supplement intake of this nutrient–also, where do you draw the line between food/supplement (i.e. danny roddy supports egg shell calcium. is that a supplement or food?)

    2)If PTH is reduced due to increased calcium intake, then doesn’t the significance of vitamin D also get reduced (seeing as how PTH is involved in activating calcitriol)

    Thanks again for any input on the matter =)

  37. Thanks, Paul, for weighing in. If you or any of your readers know of a reputable forum where folks with hormone imbalance share their experiences with natural (not BHRT) re-balancing, please share. Crowdsourcing appears to be the best bet in this situation.

    I get that time will tell whether diet, nutrition and infection cures are enough to remedy hormone imbalance. I’m pursuing all those leads. Unfortunately, a lot of women like myself are losing precious childbearing years while trying to figure this out, creating a real time crunch. It’s enough to tempt one to experiment with an otherwise dubious idea like pounding sugar, just in case it works. :/

  38. @JW – I enjoyed reading your comments.

    As Paul say, people are unhealthy in their own way, and people have come to hormonal imbalance through their own unique pathway, so there is definitely not one way to fix hormonal problems. But I do think there are some patterns. And sometimes the “least possible harm” approach to medication or supplements can be helpful. I had ovulation three days after taking half a grain of Thyroid-S (desiccated thyroid) after seven months of absence. Was it worth it? For me yes. The negative consequences, including for my body to live with chronic low T3 and very low progesterone were too many. Maybe I could have fixed it by diet only in another month, in another year. I do not know. My progresterone is still on the low side. Will I use a progesterone cream? No. I do not want to downregulate the natural production. But I am not saying I would never do it, in the right context. For me, significantly increasing my sugar intake was very hard psychologically. Seriously, it was. What I see now, holding thyroid supplement constant, is that when I reduce the sugar intake, my body weight goes down, but my body fat goes up, ie. I am loosing lean mass/muscle rapidly. I am not saying it works this way for everyone. To the contrary. But I think it is something people with hormonal problems might want to experiment with, as long as sugar is eaten in the right context, meaning a PHD like diet. Paul, you are open to the fact that ketogenic diets can be therapeutic for a lot of people – maybe higher sugar diets can be therapeutic for some people too? : )

  39. Peggy at the Primal Parent

    I am so glad you wrote this article! I find Ray Peat really interesting but I haven’t been able to wrap my head around the fructose recommendation. It seems you could not either. Indeed, glycogen replacement is an odd defense of fructose unless all of Peat’s followers were athletes, which they’re not. And anyway, you’ve argued well against that defense. Good job and thanks!

  40. What if nature defines athletic differently than what we do?

  41. From my understandings of Peat, he is not advocating ingesting 100% fructose sources.
    He seems to recommend fruit (contains glucose and fructose) and ordinary sugar; sucrose (a disaccharide, consisting of glucose and fructose).

    I do not know if Peat has a specific ration of fructose to glucose, but JRAC has indicated in his comment above that it is 2:3, ie. 40% fructose, 60% glucose

    @JRAC, did i get that right? do you have a Peat ref link for this.

  42. As far as I know the sugar in fruit is far from being all fructose. So if someone gets half their sugar from fruit and the other half from other sources, it will be around 25% fructose because fruit has other types of sugar in it too, it is not all fructose.

  43. JW,as far as child bearing goes, dr.’s at the turn of the last century used to call the thyroid the third ovary. When the thyroid is working properly,the sex hormones are working,the cycle is working, etc. I know this is a simplistic view, but when you get your temp. up to normal(98.6)on a steady basis things should start to fall into place.

  44. @kevin – Thanks for that. It renews my hope that I can work these things out naturally. I have subclinical hypothyroidism and will start an iodine protocol soon, so maybe that will bring good results. As for temps, I’ve read that there are so many factors that influence daily temps that they’re not a particularly reliable measure of thyroid health. I dunno. But I collect the data anyway (biodata collection has become a real skill lately – too bad it can’t go on my resume!) and will pay closer attention. Thanks for the encouragement.

    @ ET – Great to connect with a similarly situated person. I’d like it if Paul would give you my email address, if he would be so kind, so that we can talk shop, if you’re up for it.

  45. Hi JW,

    I’ve passed your address on.

    Best, Paul

  46. Hi Darrin,

    Peat doesn’t set down strict guidlines about what one should or shouldn’t do as such; he just provides information and lets people interpret it as they will. A couple of statements he’s made:

    ‘Ideally I’d get half my calories from fruit’
    ‘The optimal amount of fructose to glucose appears to be 1 to 2 ratio (so 33:66).’

    He prefers fruit over starch but says well buttered potatoes (or squashes) for example are ok but like I say he does prefer fruit.

    Pretty sure that’s where he said that but here are the rest of the interviews:

  47. Hey Paul,

    I have been experimenting with fructose consumption on an n=1 basis, and have found it to be almost completely harmless (at least as best as I can tell) in the context of wheat and vegetable oil free diet. Granted, I am very lean, almost certainly <10% body fat, but to me the fact that I have remained that way despite consuming fructose at near Danny Roddy levels for probably close to 6 months is very telling. I was not always naturally lean, and in fact was chubby for basically my entire life until I first went paleo in 2009.

    Lately I tend to eat a very high carb diet, with the bulk of my carbs coming from white rice (and white rice pastas), corn (in the form of popcorn and corn pasta), ice cream and orange juice. For the last few months, I have been eating a pint of ice cream in a single sitting on a regular basis (3-4x per week or more), often as a standalone meal an hour or two before bedtime. Biomarkers of health have remained favorable, and qualitatively I believe that I have seen improvements in my sleep quality and energy levels.

    Anyway, at this time I believe that I can assert with a high level of confidence that fructose is not detrimental to my health, even at relatively high levels (compared to a PHD, though maybe not compared to a SAD). Extrapolating to others, I doubt that fructose is toxic in and of itself, though it is clearly an extremely rewarding food and may cause overconsumption in some individuals (or may cause overconsumption of toxins when paired with them) that could confound observational data.

  48. Dr. Robert Lustig made national news today …

    UCSF scientists declare war on sugar in food

    “Like alcohol and tobacco, sugar is a toxic, addictive substance that should be highly regulated with taxes, laws on where and to whom it can be advertised, and even age-restricted sales, says a team of UCSF scientists.

    In a paper published in Nature on Wednesday, they argue that increased global consumption of sugar is primarily responsible for a whole range of chronic diseases that are reaching epidemic levels around the world.”


  49. Zachariah Salazar

    Theres some cool posts here but if youre going to talk about what Peat recommends then you have to read his stuff. He has numerous free articles, he has a newsletter, he has many books but what he DOES NOT have is a diet book!

    He has recommendations based on his practice. Anyone can go out and read and listen to his podcasts and begin to understand that he CHANGES his recommendations based on the issue and the person at hand.

    This blog (PHD)represents a tremendous amount of INDIVIDUALIZATION for a preplanned diet. All Dr Peat is recommending is individual variations based on the data he has amassed.

    If you listen to his podcasts one minute he’ll answer a very specific question with an answer based on questions he asks of the individual. When asked what the optimal ratio of macronutrients is he replies by basically saying he doesnt know. Maybe 1/3, 1/3, 1/3… But that depends on the quality of each of the macronutrients. And to reiterate what was previously said with good nutrition and quality macronutrients you could be healthy with an excess of ANY of the macronutrients.

    When asked about difficulty sleeping he recommended a serving of ice cream before bed. But when exhaustion was more the issue he recommended a serving of cottage cheese then a couple of ounces of ice cream before bed. Its about the individual.

    What the majority get to hear is an amalgam of his ideas on health through cell respiration and hormones plus adjustments for individuals. No one is quoting from “Dr Raymond Peat’s Diet That Rules All” book.

    Danny Roddy has had great results with his HAIR LOSS diet in terms of health regardless of the hair issue.

    My clients are doing awesome on some Peat-ness but it doesnt totally look like Roddys plan either. Amazing weightloss with 150-400 grams of sugar a day. 70-150 grams of protein a day. The rest fats.

    My fiance ate about 1600-1900 cals a day on PHD. She eats 2500-4000 a day on our vague accumulation of Peats data. Peat belives that people get to eat so little to lose wieght cuz their metabolism is so slow from PUFAs seed oils grains bromine etc. He mentions that in 1940 a sedentary woman should be able to lose weight on 1700 cals a day. Peat believes its not so much about lack of exercise and too much food its too much food cuz people are starving from nutrient poor food combined with the idea that they cant eat as much due to slow metabolisms. So weight is a metabolism nutrition thing and less an exercise thing.

    When Ray Peat discusses sugar/sucrose is is always applying it to a background of healthy food no PUFAs no grains, plenty of sunlight, lots of rest, no excessive exercise, eat liver, eat gelation to balance out the inflammation of red meat if you dont eat bone broth soup, drink coffee for iron control etc. It is in this environment that the body handles all the macronutrients well.

    Peat uses sugar to control stress along with salt and many other food combinations. He addresses food impurities as a main cause of poor reactions to commonly reactionary foods. As a guy that drank about a gallon a day of milk for 35 years Ray describes how additives like cheap vitamins or gums has made him sick. He uses OJ as a supp because it has high nutritional value and is easier to acquire than many fruits but there are over 100 TROPICAL fruits he recommends.

    His basic plan would be meat fruit sugar coffee dairy and eggs.

    He is concerned about the poor health of the American gut. You would be able to eat a large amount of fruit if you were PUFA and grain free and living 200 years ago. But a modern gut cannot handle many of the available fruits due to their fiber content. The fiber is too rough on a leaky gut and if your gut population has a disproportionate level of bad bacteria then the fiber can feed those bacteria leading to a more out of balance intestinal environment.

    He is aslo very aware of the status of the food industry. He gives excellent reason for why apple juice and apple cider are bad that have only to do with available preparations.

    When it comes to starches he recommends the 3 best: white rice, potato, AND corn if it’s masa harina. Interesting personal fact-I myself have avoided corn because of all the problems it causes to my gut my skin etc. But when my fiance makes corn tortillas or chips fried in coconut oil from masa harina I have no problem with them. He tells an interesting story about an experiment he ran in Mexico and his discovery that the way masa harina was treated traditionally is what made it edible.

    Peats main issue with starches involves persorption and tiny particle that can end up in the ends of capillary beds possibly causing slight immune responses. He recommends thoroughly cooking said starches.

    You want more interesting stuff to talk about:

    Big difference with PHD: doesnt like PUFAs or MUFAs, doesnt like any seeds or nuts, fruits and sugars primary to starches, doesnt see any fatty acid as essential
    therefore eats leaner warm water fish and stays away from salmon and hes not a fan of lactate heavy foods so yogurt for example is more of a condiment that a food choice…

    He digs raw carrots for beating up lipopolysaccharide bacteria that wrecks the gut with endotoxins. He likes Aspirin. I’ve taken 4 grams a day 😉

    He has a lexicon of references and many great book and author recommendations. His free articles are awesome providing many answers and fun questions.

    I actually thought the PHD had some heavy influences when I stumble on to it: the comments on coconut oil were a big attraction for me.



  50. Zach, very well said.

Leave a Comment

NOTE - You can use these HTML tags and attributes:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This site uses Akismet to reduce spam. Learn how your comment data is processed.