Category Archives: Perfect Health Diet - Page 8

Hunter-Gatherer Macronutrient Ratios: More Data

Posted by on February 3, 2011 59 comments

At the very beginning of our book’s macronutrient discussion (p 8), we offer four reasons to believe in a macronutrient intake around 30% carb, 55% fat, 15% protein – a relatively low-carb diet by modern standards. (Note: these ratios were updated slightly in our 2012 edition.)

One of them is that hunter-gatherer populations ate approximately in these proportions. Our cite was a 2006 review paper by Loren Cordain [1] that was based on an earlier paper (by Cordain, Janette Brand-Miller, S. Boyd Eaton, and others) in the American Journal of Clinical Nutrition [2]. These papers estimated hunter-gatherer diets from data in JP Gray’s 1999 corrected version of the 1967 Ethnographic Atlas of GP Murdock. [3]

The Cordain et al paper in AJCN was accompanied by an editorial from Katherine Milton [4] and a series of letters. Milton argued [5] that the underlying data was unreliable. Chris Masterjohn summarized her point in his review of our book:

Katherine Milton has pointed out (here) that when “casual agriculturists” and hunters that hunt with modern guns are excluded, Cordain’s 229 “hunter-gatherers” are reduced to only 24. Although Milton often seems biased in favor of plant foods, I’m not sure how much “hunter-gatherers” hunting with modern guns can tell us about what humans were eating 40,000 years ago.

The Ethnographic Atlas was compiled from anthropological contacts early in the 20th century, long after first contact of these peoples with modern societies. The peoples involved had changed their lifestyles based on trade, acquiring guns and other tools as well as access to agricultural goods. Milton was concerned that these acquisitions may have distorted their diets. Milton was also concerned that the (largely male) anthropologists who collected the data may have neglected the activities of women, who gathered plant foods, in favor of men, who hunted.

Milton presented no data of her own. Clearly it would be desirable to have data acquired directly from hunter-gatherer tribes not using guns or agriculture, and from a source other than Cordain and Eaton, whose version of the Paleo diet looks suspiciously influenced by the lipid hypothesis.

Well, we’re in luck.

Miki Ben Dor of the Hebrew-language blog Paleostyle has written to tell me of an interesting 2000 paper [6] by anthropologists Hillard Kaplan, Kim Hill, Jane Lancaster, and Ana Magdalena Hurtado in the journal Evolutionary Anthropology. Hurtado and Hill later became collaborators on Cordain’s acne paper [7].

Miki discusses the paper in Hebrew here. (Miki, by the way, wrote a very nice review of our book here.) For the benefit of those who don’t read Hebrew, I thought I’d present the data.

The Data

The authors present data on diets from nine hunter-gatherer cultures. The essentials are in this table (click to enlarge):

Seeds and nuts are significant only for the !Kung, who ate mongongo nuts, which provide primarily fat calories.

Fruit was a large source of calories only for the Nukak, Gwi, and Hadza. The “fruit” the Nukak of Colombia eat is the palm fruit, which has a small amount of starch but whose calories consist overwhelmingly of fat calories from palm oil. Palm oil is a healthy oil that is 50% saturated fat, 40% monounsaturated fat. The “fruit” the Hadza ate was also fatty, averaging 1200 calories/pound compared to 200 calories/pound for sweet fruits; sources included Baobab fruit and Kongoro berry. The Gwi San consumed melons, a sweet fruit.

Save for the Nukak and Hadza, the sum of root, fruit, and “other plant” intake is a fair approximation to total carb plus fiber calories.  These added up to 242 calories/day for the Onge, 137 calories/day for the Anbarra, 469 calories/day for the Arnhem, 277 calories for the Ache, 386 for the Hiwi, 300 for the !Kung, and 1200 for the Gwi. In all cases except the Gwi, carb intake was less than 20% of calories.

For the Nukak, carb intake was probably also in this range. So seven of nine cultures ate 10% to 20% carbs; for the Gwi San a majority of calories were carbs, and for the Hadza perhaps 40% of calories were carbs.

Meanwhile, foods obtained by men – primarily meat – provided 70% to 85% of calories for the Onge, Anbarra, Arnhem, Ache and Hiwi; 60% for the Nukak, about 50% for the !Kung, and 65% for the Hadza. [Table 2]

Another interesting observation from this data is that fruits were generally a less important source of calories than roots. It is likely that starches have outweighed sugars as a source of calories for humans for at least the last 2 million years.

Conclusion

In the book we argued that most hunter-gatherer cultures, when they weren’t constrained by Malthusian population pressures and famines, probably ate close to a 20% carb, 65% fat, 15% protein macronutrient ratio.

This data is largely consistent with that. Indeed, most cultures seem to have eaten slightly less than 20% carbs.

This paper does not provide sufficient data to break down the protein vs fat composition of the diets. But since protein seems to be eaten to a specific target of around 15% of energy / 360 calories by nearly all observed cultures, we can guess that that’s how hunter-gatherers ate as well. The acquisition of fat calories from fatty fruits and nuts, like palm fruits, confirms that fat was sought after.

The preference for starchy roots and tubers over sugary fruits is also no surprise. Not only are roots and tubers more calorie rich than most fruits, they are also (given the problematic nature of fructose) probably the healthier choice!

We don’t idolize Paleolithic or modern hunter-gatherer diets, so I won’t say that this data by itself proves our diet is correct. But I think it does add to the evidence that ancestral humans ate a diet that closely resembles ours.

References

[1] Cordain, L. “Implications of Plio-Pleistocene Hominin Diets for Modern Humans,” pp 363-383 in Peter S. Ungar, ed., Evolution of the human diet: the known, the unknown, and the unknowable, New York: Oxford University Press, 2006. http://www.thepaleodiet.com/articles/2006_Oxford.pdf.

[2] Cordain L et al. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr. 2000 Mar;71(3):682-92. http://pmid.us/10702160.

[3] Gray JP. A corrected ethnographic atlas. World Cultures J 1999; 10:24–85. Murdock GP. Ethnographic atlas: a summary. Ethnology 1967; 6:109–236.

[4] Milton K. Hunter-gatherer diets—a different perspective. Am J Clin Nutr. 2000 Mar;71(3):665-7. http://pmid.us/10702155.

[5] Milton K. Reply to L. Cordain et al. Am J Clin Nutr 2000 Dec;72(6):1590-1592. http://www.ajcn.org/content/72/6/1590.full.

[6] Kaplan HS, Hill KR, Lancaster JB, Hurtado AM. A Theory of Human Life History Evolution: Diet, Intelligence, and Longevity. Evolutionary Anthropology 9:156-185, 2000. http://www.unm.edu/~hkaplan/KaplanHillLancasterHurtado_2000_LHEvolution.pdf.

[7] Cordain L et al. Acne vulgaris: a disease of Western civilization. Arch Dermatol. 2002 Dec;138(12):1584-90. http://pmid.us/12472346.

Perfect Health Diet: Weight Loss Version

Posted by on February 1, 2011 396 comments

We started 2011 with a discussion of Experiences, Good and Bad, On the Diet; which led us into the issue of weight loss, especially for peri-menopausal and older women.

This is an especially poignant issue for erp, who is 76 years old and would like to lose weight for her upcoming knee replacement surgery, but cannot walk.

This is the toughest possible scenario for weight loss:

  • Whether for genetic (X vs Y chromosome) or hormonal reasons, women are more prone to putting on weight than men. (Men are more prone to diabetes.)
  • Hormonal changes after menopause seem to make it tougher for women to lose weight.
  • A petite woman doesn’t need as many calories as a larger person … but her micronutrient needs, and thus her appetite, may still be high.
  • Aging brings more efficient energy utilization and reduced energy expenditure. Thus, the elderly have a smaller energy “sink” in which to dispose of excess fat. A teenager can eat like a horse and stay thin; not so an older person.
  • An injury that prevents walking makes it even harder to burn off fat. Walking is a tremendous aid to fat loss.

Designing a weight loss diet for someone like erp really forces a hard look at how to optimize a weight loss diet. Get it even a little bit wrong, and the diet either won’t work for weight loss, or will be malnourishing.

The Three Keys for Weight Loss

The three keys for an effective and healthy weight loss diet, as I see it, are:

  1. Elimination of food toxins. Food toxins are the primary cause of obesity and you can’t expect to cure a condition by causing it!
  2. Perfect nourishment. The diet should be as nourishing as possible. The dieter should be in the “plateau range” of every nutrient – vitamins, minerals, organic molecules, carbs, protein, and fats.
  3. Calorie restriction. You have to be in energy deficit to lose weight.

The main food toxins to avoid are fructose, polyunsaturated fat, and wheat (see Why We Get Fat: Food Toxins). In my advice to erp, I suggested replacing some of her fruit with “safe starches” like potatoes, and replacing her PUFA-containing nuts with low-PUFA macadamia nuts or other foods.

But the harder part is achieving a calorie restricted diet when so few calories are being expended, and yet avoiding malnutrition. How may that be done?

Eat Protein and Carbs; Reduce Fat

This may surprise many readers, since we’re fat-friendly, but there should be no reduction in carb or protein consumption on weight loss diets. Calorie restriction should come out of fat.

The Perfect Health Diet “plateau range” for carbs and protein is 600 to 1200 calories. Eating less than 600 combined carb+protein calories per day raises the specter of either protein deficiency (leading to hunger) or glucose deficiency (leading to zero-carb dangers).

So if a typical daily intake is 400 carb calories and 300 protein calories, there’s really not much room to cut protein or carbs.

Remember that the body doesn’t have a significant store of carbs; the body’s total glycogen supply amounts to about a day’s needs. Nor does it have a store of protein, apart from skeletal muscle; and you don’t want to lose your muscle.

But it does have a large store of fat – those adipose cells that you want to shrink.

So to conserve muscle and reduce fat tissue, you have to eat your normal allotment of protein and carbs while restricting fat intake. As long as there is no serious dysfunction of adipose cells, they will release fat as needed to meet the body’s fat needs. And that’s what you want – fat being moved out of adipose cells to be burned.

So your calorie-restricted weight loss diet will be just as nourishing as your regular diet. Only the source of the nourishing fats – adipose cells instead of food – will be different.

Eat Nourishing Fats

But not all fat can be removed from the diet. The reason is that not all nutrients found in fat-containing foods are stored in adipose cells.

You see, fats are stored in adipose cells as triglycerides. But we need to get other lipid molecules, not just fatty acids, from food. The really crucial molecules are the phospholipids, especially phosphatidylcholine.

Choline, inositol, and a few others are organic molecules are bonded to fats in cellular membranes. We need to obtain these from our foods in order to be well nourished.

Diets low in choline strongly promote obesity. Therefore, anyone seeking to lose weight should be sure to eat a choline-rich diet.

The easiest way to do that is to eat 3 eggs a day and a ¼ pound beef liver once a week.

Another type of lipid that may be missing from adipose cells are omega-3 fats. Balancing the omega-6 to omega-3 ratio is helpful against obesity, and most people are omega-3 deficient. So eating up to 1 pound of salmon or sardines per week may assist weight loss.

Beef and lamb – meats that are low in omega-6 fats – would be good choices for any additional meat.

Be Super-Nourished

The body’s appetite regulation mechanisms are highly attuned to your micronutrient needs. Micronutrient deficiencies will tend to induce a strong appetite for food, as your body tries to get you to obtain more nutrition. This could be a major reason why “empty calories” such as cotton candy are fattening.

Our book has some examples of “micronutritious foods”: variety meats, bone soups, seaweed, shellfish, eggs, and vegetables.

Nutritious, low-calorie foods like bone soups can be very helpful for weight loss. Soups can also be a good way for someone who doesn’t like vegetables to obtain them.

In addition, I would recommend that every person on a weight-loss diet take our full supplement regimen: a daily multivitamin, D, K2, C, magnesium, copper, chromium, iodine, and selenium. Also, I would suggest taking our optional B vitamins: thiamin, riboflavin, pantothenic acid, biotin, vitamin B6, vitamin B12, and choline (note the exclusion of niacin and folic acid).

Keeping Calories Down

What is the minimum calorie intake that meets all these nutrient considerations?  Eggs, salmon, and beef have more fat than protein, so if you’re aiming for 400 carb calories and 300 protein calories, you’ll probably eat at least 500 fat calories per day. So it would seem to be impossible to go below about 1200 calories per day while still being well nourished.

The place to cut calories, then, is the extra fats. Perfect Health Diet favorites like butter, coconut oil, and cream are, sadly, top candidates for reduction.

Of course, the more active you are, the more you can include those fats.

For less active people, the Weight Loss Version of the Perfect Health Diet becomes similar to a lot of popular diets. Many diets recommend a roughly even calorie distribution, with 30-40% of carbs, protein, and fats. This is what a calorie-restricted version of the Perfect Health Diet should look like too.

So, the perfect day in a weight loss diet: soup, potatoes or other safe starch, salmon, eggs, vegetables. Not too much fat in the sauces!

A good meal might look like this:


Mash the sweet potato with eggs instead of butter, and this would fit our weight loss recipe.

Conclusion

It’s a little humbling that I’ve started 2011 with 5 posts on the subject of healthy weight loss, but have only scratched the surface of this complex topic.

For instance: In the book we used the rubric “metabolic damage” to describe the biological dysfunction associated with obesity. But we never really chased the complex biology of exactly that damage consists of – and how it can best be healed.

Today, I’ve presented what I believe is the best strategy for healthy weight loss. But other techniques – such as ketogenic dieting, intermittent fasting, exercise, and more – can contribute to healing the metabolic damage of obesity. As 2011 goes on, I’ll return to this topic.

I am intensely interested in the experiences of anyone trying to lose weight using our diet, and I hope that together, we can understand the disease of obesity better, and figure out good ways to achieve both healthy weight loss and a permanent recovery from metabolic damage of all kinds. So please, if you are trying to lose weight, keep me posted on your experiences, whatever they may be!

Related Posts

From 2011:

From 2010:

Low-Protein Leanness, Melanesians, and Hara Hachi Bu

Posted by on January 27, 2011 71 comments

Gunther gatherer raised an interesting issue in a comment to Tuesday’s post.  Protein may be satiating in the short run; but what about the long run?

[H]igh protein keeps you full at first. But no one really knows for how long. Eventually it stops working and you find you’re eating a lot ON TOP of all the high protein you were already eating. All of us here tried Atkins long ago and fell off the bandwagon more than enough times to know it gets boring, stops working against hunger and doesn’t keep the fat off forever.

I agree. This is why we recommend a version of the normal Perfect Health Diet, which is normal — not high — in protein, for weight loss. Our diet isn’t the quickest way to lose weight, but we think it is likely to work best in the long run.

The Long-Term Effects of High-Protein Diets

I argued in Tuesday’s post that the satiating effects of protein had to be temporary, and that in the long run higher protein might cause, not reduced appetite, but only a slight change toward a leaner body composition.

A more interesting question is:  could high-protein diets be positively harmful?

Maybe!  Studies in both animals and humans indicate that eating high protein during childhood creates a predisposition for obesity in later life.

For instance, rats raised on a high-protein diet in childhood are more likely to become obese when given calorie-rich (sugar and fat) diets in adulthood. [1] The researchers conclude:

Our research demonstrating a significant susceptibility to an obese phenotype in rats weaned onto a high-protein diet and then challenged in adulthood with a high-fat high-sucrose diet suggests that lasting changes result from altering the composition of the first solid food that is consumed throughout growth into early adulthood. While all rats in this study consumed the same high energy diet during the last 6 weeks of the intervention, distinct metabolic profiles remained evident from exposure to the different diets during growth. This would suggest that these changes, either long-lasting or perhaps permanent, ultimately influenced the adiposity response of these rats to a high energy challenge in adulthood. Overall, it appears that a long-term diet high in protein, when mismatched with a high energy challenge, has negative effects on body mass and hormones and genes involved in glucose and lipid metabolism. [1]

The same phenomenon occurs in humans. In the book we mentioned a study showing that slightly higher protein level in infant formula – 9% protein vs 7% normally – caused children to become overweight two years later. [2]

So parents, let your kids follow their taste buds to high-carb, high-fat diets!

Might adult high protein diets promote later-life obesity too? I’m not aware of evidence, but I don’t think the possibility can be ruled out. I will look for evidence when I do research for two future blog series: one on protein intake, aging, and longevity; the other on connections between obesity and the human aging program.

Can You Be Lean on a Low-Protein Diet?

Tuesday’s post cited research indicating that we have a set point for protein intake: humans are genetically programmed to seek around 360 protein calories per day, and appetite becomes satiated once that is achieved.

But if protein intake determines appetite, then it seems those eating a low-protein diet face a Hobson’s choice:

  • If total calories are not increased, then the low protein dieter can expect to have a chronically unsatisfied appetite.
  • If total calories are increased, so that appetite is satisfied, then the low protein dieter can expect a higher equilibrium weight and a slightly less lean body.

Is it possible, then, to restrict protein, eat mostly carbs and fat which we know are the ingredients of appetizing desserts – and still achieve a lean healthy body, and feel comfortable? 

Yes, I believe so.

Melanesians Do It

Gunther pointed out that Melanesians are lean and long-lived on low protein diets:

I think it would be a bit fairer to include some consideration and explanation of Melanesians and their extremely low protein diet (anywhere from 10% to only 3% protein daily). Their extremely high level fitness and body composition flies in the face of all of these high protein studies.

It’s true: Kitavans, Tokelauans, and other Melanesians eat high-carb and low-protein, yet they’re noted for “extreme leanness.” [3] Why?

Well, first of all, the Melanesian islander diet is a variant of the Perfect Health Diet:  it is entirely free of food toxins. As I argued last week, eliminating toxins is the key to healthy weight regulation. But there are other factors.

Coconut Oil

The most abundant fatty acid in the diets of Kitavans and Tokelauans is lauric acid, the 12-carbon fatty acid which is the predominant fatty acid in coconut oil. [4, 5] These shorter-chain fatty acids are ketogenic and have significant effects on the body: for instance, they raise HDL levels. They also make people lean.

In one study, 8 weeks taking 1 tbsp per day coconut oil caused a significant decrease in body weight, waist size, and blood triglycerides. [6] In another, obese women who received 2 tbsp (30 ml) coconut oil per day slimmed their waist and increased HDL without an increase in LDL, while a comparison group receiving soybean oil did not slim their waist and had lower HDL with higher LDL and total cholesterol. [7]

Resistant Starch

Another feature of the Melanesian diet is that the biggest share of calories came from “safe starches” like yams, sweet potatoes, and sago.

These foods have a lot of fiber in the form of “resistant starch.” Digestion of resistant starch by colonic bacteria produces a lot of butyrate, a short-chain fatty acid that strongly promotes leanness.

For example, butyrate improves insulin sensitivity and prevents rats from becoming obese. [8]

Hara Hachi Bu

But the most reliable strategy seems to have been worked out by Asian and Pacific cultures long ago, many thousands of years ago.

The key is that if the diet is well nourishing, then appetite will be mild and easy to consciously control. What will be experienced is not hunger, which indicates malnourishment, but a mild desire for food that can easily be ignored.

There is an ancient Chinese saying:

“Eat until you are eight-tenths full, walk 100 steps after meals, live 99 years.”

In Japanese the saying is Hara Hachi Bu, eat until eight-tenths full. Hara Hachi Bu is common practice in Okinawa, where it helped produce the world’s most long-lived population.

As we note in the book, the traditional Okinawan diet is extremely close to the Perfect Health Diet: the Okinawan diet was rich in safe starches and animal fats, and near the low end of our recommended protein range: Okinawans ate about 300 g (2/3 pound) meat and fish per day.

The key here is that on a low-protein diet, eating until eight-tenths full is not a calorie-restricted diet. It is a calorie-sufficient diet that isn’t quite satiating because it is low in protein.

Intermittent fasting is a helpful part of Hara Hachi Bu. Eating only within a relatively short window each day makes it easy to keep calories down.

My Experience

I have been practicing protein restriction for several years, eating coconut oil and safe starches for several years, and practicing daily intermittent fasting for over six months. I drink tea or lemon-flavored water through the morning, and on most days eat only between 2 pm and 8 pm. If I snack during the fast it is usually either a piece of dark chocolate or some coconut oil.

I sometimes go many days eating relatively little, then eat a lot for a few days. Physical activity – sports, intense exercise, running – increases my appetite noticeably. Regardless, I never feel hungry. It is easy to complete the daily fast: some tea, sometimes with coconut oil or dark chocolate, is enough. I now do total fasting on religious fast days – for instance, I now do a 64-hour fast from Holy Thursday through Easter Sunday morning. Generally, as soon as I focus my attention on work I forget that I wanted food.

(This is a very good sign for my health, by the way. During my long chronic illness I couldn’t tolerate fasting at all.)

I haven’t noticed difficulty adding muscle when I work out. I believe I would add muscle more easily on a higher-protein diet, but as it is I add muscle more easily than I used to on the standard American diet. I’m content with my body composition.

Conclusion

I am convinced that by eating coconut oil, getting carbs from safe starches, and practicing intermittent fasting and Hara Hachi Bu, most people can become well-muscled and lean on a low-protein diet without any sense of hardship.

Since a carb-fat mix is the classic recipe for dessert, this makes for an extremely tasty diet.

If you want the surest way to lose weight over the next few days, eat a high-protein diet. But if you want a long-term diet that maximizes longevity by restricting protein, consider eating a tablespoon or two of coconut oil per day, fasting for 16 hours a day, and finishing your meal eight-tenths full.  

If you walk a hundred steps after dinner, you just might become a healthy centenarian!

References

[1] Maurer AD et al. Consumption of diets high in prebiotic fiber or protein during growth influences the response to a high fat and sucrose diet in adulthood in rats. Nutr Metab (Lond). 2010 Sep 29;7:77. http://pmid.us/20920272.

[2] European Childhood Obesity Trial Study Group. Lower protein in infant formula is associated with lower weight up to age 2 y: a randomized clinical trial. Am J Clin Nutr. 2009 Jun;89(6):1836-45. http://pmid.us/19386747.

[3] Lindeberg S et al. Haemostatic variables in Pacific Islanders apparently free from stroke and ischaemic heart disease–the Kitava Study. Thromb Haemost. 1997 Jan;77(1):94-8. http://pmid.us/9031456.

[4] Lindeberg S et al. Lipoprotein composition and serum cholesterol ester fatty acids in nonwesternized Melanesians. Lipids. 1996 Feb;31(2):153-8. http://pmid.us/8835402.

[5] Lindeberg S, Vessby B. Fatty acid composition of cholesterol esters and serum tocopherols in Melanesians apparently free from cardiovascular disease – the Kitava study. Nutr Metab Cardiovasc Dis. 1995; 5: 45-53.

[6] Xue C et al. Consumption of medium- and long-chain triacylglycerols decreases body fat and blood triglyceride in Chinese hypertriglyceridemic subjects. Eur J Clin Nutr. 2009 Jul;63(7):879-86. http://pmid.us/19156155.

[7] Assunção ML et al. Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity.  Lipids. 2009 Jul;44(7):593-601. http://pmid.us/19437058.

[8] Gao Z et al. Butyrate improves insulin sensitivity and increases energy expenditure in mice. Diabetes. 2009 Jul;58(7):1509-17. http://pmid.us/19366864.

Protein, Satiety, and Body Composition

Posted by on January 25, 2011 62 comments

A number of studies have found protein to be the most satiating macronutrient, with fat moderately satiating, and carbs least satiating.

Thus, when people reduce carbs and increase protein, their appetite declines and they almost always reduce calorie intake. This can leads to rapid short-term weight loss. This is why most popular weight loss diets are high in protein: increasing protein causes dieters to quickly lose some weight, encouraging them to continue.

A 2005 editorial in the American Journal of Clinical Nutrition summarized the evidence that higher protein intake is helpful for weight loss:

The higher than usually recommended protein content of many popular diets, such as the Atkins Diet, The Zone, and The South Beach Diet, seems to point at possible solutions to the obesity epidemic. Many national dietary guidelines have, until recently, recommended that only 10–20% of the calorie content of the diet come from protein; however, 30–40% of the calorie content in the aforementioned diets comes from protein, at the expense of carbohydrates. Newer research indicates that the high-protein content of these diets may actually be the reason for their partial success in inducing weight loss, despite no restrictions in total calories (2)….

In this issue of the Journal, Weigle et al (3) showed that an increase in dietary protein from 15% to 30% of energy and a reduction in fat from 35% to 20%, at a constant carbohydrate intake, produces a sustained decrease in ad libitum calorie intake and results in significant weight loss….

Weigle et al’s results clearly showed that protein is more satiating than is fat, and previous studies have shown that protein is more satiating than is carbohydrate (4). Moreover, diets with a fat content fixed at 30% of calories produce more weight loss when high in protein (25% of energy) than when normal in protein (12% of energy): 9.4 compared with 5.9 kg after 6 mo; after 1 y, evidence was found to suggest that the high-protein diet, independent of the loss of total body fat, resulted in a significant loss of visceral fat (5). [1]

But there are downsides to high protein consumption. Various animal experiments have found that longevity is increased with protein restriction. Also, protein restriction promotes autophagy, which enhances immunity to intracellular bacteria and viruses. So higher protein intake may shorten lifespan and increase the risk of disease.

In a post on his blog (linked in this comment), Dennis Mangan introduced us to the “protein leverage hypothesis.” This hypothesis is put forward in a 2005 paper by SJ Simpson of Oxford University and D Raubenheimer of the University of Auckland [2].

The Satiating Power of Protein

The paper has some graphs which neatly illustrate the satiating power of protein. When animals are given a food formula with a lower protein fraction, they eat more total calories.

Here are some data from rats (b) and chickens (c). The numbers are in kiloJoules; divide by 4.18 to get calories. The animals were on feed formulas with a constant fat content, but different carb-protein ratios. Each data point represents a diet with a different P:C ratio.

If both macronutrients were equally satiating, then the animals would eat the same amount of calories regardless of their food’s protein-carb ratio. The data points would fall on a 45º line (say, for chickens, a constant 1000-kJ line connecting the 1000 kJ mark on the y-axis with the 1000 kJ mark on the x-axis).

But they don’t:  if a line were fitted to these points, it would be much closer to vertical than 45º. The rats, for instance, eat around 150 kJ protein and 75 kJ carb if given high-protein food, but 75kJ protein and 300 KJ carb if given high-carb food. That’s 225 kJ (54 calories) on a high-protein diet, but 375 kJ (90 calories) on a high-carb diet.

The chickens and rats act like protein dominates appetite control:

  • A shortage of protein makes them hungry, and it takes a lot of carbohydrate to satisfy that hunger. So they eat a calorie excess.
  • An excess of protein satisfies their hunger and causes them to quit eating while they are still in calorie deficit.

Evidence in Humans

The same sort of thing happens in humans:

Results a, b, and c are from “short-term” experiments that varied from 2 days to 6 months in length. Results d, e, f, and g are from “long-term” experiments.

People tend to gravitate toward a protein intake of 1520 kJ (360 calories). This can be construed as the “normal” human protein intake, and tends to occur near a carb+fat intake of 8000 kJ (1900 calories). So the “normal” protein fraction of the diet is 360/2260 or 16%. This is consistent with epidemiological data, which finds that nearly everyone worldwide eats near 15% protein.

A line fit to the data has the same steep slope as the animal experiments, but note something interesting. The short-term experiments have a very steep slope, but the long-term experiments have a slope much closer to 45º.

This has to happen. Otherwise, a high-protein diet would lead to permanent calorie deficit which, over time, would lead to starvation. A low-protein diet would lead to permanent calorie excess which, over time, would lead to obesity.

Since we know people neither starve nor become obese due to small adjustments in protein fraction, they must adjust their calorie intake. In the long run, protein no longer controls calorie intake. So there is great protein leverage in the short-term, but much less protein leverage in the long term.

Simpson and Raubenheimer try to develop protein leverage into a theory of obesity. It’s not a very good theory, so I’ve relegated it to an appendix.

Instead, I’d like to talk about what this satiating power of protein means for Perfect Health Dieters.

Implications for Perfect Health Dieters

We have a fairly broad healthy protein range, 200 to 600 calories per day, which brackets the “normal” protein intake of 360 calories. What happens if you shift from 360 calories protein to either the low-protein or high-protein ends of the range?

IF YOU REDUCE PROTEIN: 

At low-protein intake, your appetite goes up and total calories go up. You gain a little weight, in the form of adipose mass. This causes leptin levels to increase. As we discussed in “How Does a Cell Avoid Obesity?”, higher leptin (a) lowers appetite and (b) increases thermogenesis, or destruction of fat as waste heat.

Adipose mass increases until the actions of leptin counterbalance the influence of protein leverage.

You reach equilibrium at a slightly higher fat mass and slightly higher leptin levels than on the “normal” protein intake.

IF YOU INCREASE PROTEIN:

At high protein intake, appetite goes down and total calories decrease. You start to lose adipose mass. This causes leptin levels to go down. This (a) increases appetite and (b) decreases thermogenesis, or heat generation.

Adipose mass decreases until a new equilibrium is reached. Equilibrium is reached at a slightly lower weight and slightly lower leptin than on the “normal” protein intake.

IN SHORT:

The main effect of changing the protein content of the diet is a modest change in body composition.

  • High-protein diets make you leaner and a little lighter.
  • Low-protein diets give you a slightly higher adipose reserve and make you slightly heavier.

The effect is probably small; probably just a few pounds either way. But if you’re looking for to win a bodybuilding competition and you have to become extremely lean and “cut,” you’d do well to adopt a high-protein diet.

It’s probably not a surprise, then, that people with the leanest bodies tend to be healthy but high-protein dieters. Here’s a picture of Anthony Colpo:

I think Anthony has a healthy body, but I don’t think you need to be this lean to be healthy. He would be equally healthy with a few more pounds of adipose tissue.

Conclusion

In the book we say that higher protein intake makes it easier to add muscle, and thus that it may be favored by athletes. Based on today’s post, we can adduce two other reasons to eat a high protein diet:

  1. A more chiseled body. If you want a lean, “cut” look, like Anthony Colpo, high protein will help.
  2. A controlled appetite. In a recent post, Don Matesz stated that he liked a high-protein diet because it helped him auto-regulate his calorie intake. If your goal is “effortless” (willpower-less) calorie restriction, then high protein may help – at least for a while.

However, there are reasons to restrict protein as well. Lower protein intake is likely to extend lifespan, and can increase immunity against intracellular bacteria and viruses, which are behind many late-life diseases.

Is it possible to achieve a lean, muscular body while still gaining the longevity and immunity advantages of low protein intake? And can one lose weight comfortably without assistance from a high-protein diet?  Those will be the topics of Thursday’s post.

References

[1] Astrup A. The satiating power of protein—a key to obesity prevention? Am J Clin Nutr. 2005 Jul;82(1):1-2. http://pmid.us/16002791.

[2] Simpson SJ, Raubenheimer D. Obesity: the protein leverage hypothesis. Obes Rev. 2005 May;6(2):133-42. http://pmid.us/15836464.

Appendix: The Protein Leverage Hypothesis as a Theory of Obesity

To the satiating power of protein, the protein leverage hypothesis adds two premises:

  1. That any increase in total calorie consumption leads to weight gain which induces insulin resistance in the liver, which in turn upregulates gluconeogenesis. Contrariwise, any decrease in calorie consumption reverses insulin resistance in the liver and downregulates gluconeogenesis.
  2. That the loss of protein associated with gluconeogenesis is treated by the brain’s appetite control centers exactly the same as a decreased intake of protein, and therefore that ongoing gluconeogenesis increases appetite immensely.

The theory of obesity is that once someone starts eating a low-protein diet, their appetite goes up. So they eat a larger amount of total calories, and gain weight. The weight gain causes them to become insulin resistant in the liver. Once that occurs gluconeogenesis is no longer inhibited by insulin, and the liver converts protein to glucose willy-nilly. The loss of protein stimulates appetite. But the person has to eat a lot of excess calories to get enough protein to replace the protein lost in gluconeogenesis. So weight goes up even more. There is a vicious spiral.

If these premises were correct, then:

  • Weight would be unstable. Weight would spiral out of control upward if people ate low-protein diets, and people would wither away once they started eating high-protein diets.
  • Low-carb diets would be extremely obesogenic. Every 1 calorie reduction in carb intake below the body’s daily needs of 600 calories would induce the eating of an extra 1 calorie of protein for purposes of gluconeoegenesis, and on the order of 4 extra calories of fat (by the leverage hypothesis: the P:F ratio stays constant). So each reduction of carb intake by 1 calorie leads to an extra ~5 P+F calories and an increase in total energy intake of 4 calories. Zero-carb diets would induce ravenous appetite, consumption of an extra 3,000 calories per day above the amount needed for weight stability, and obesity and metabolic syndrome would rapidly follow.

Neither is the case.