Get Started Search Icon
With a heavy heart, we share the news of Dr. John McDougall’s passing. A visionary physician and author, beloved husband, father, grandfather, brother, mentor and friend, Dr. McDougall died peacefully at his home on Saturday, June 22nd, at the age of 77.

High Protein Diets

Updated September 18, 2013

High-protein Diets: Trading Your Health for Temporary Weight Loss

Once again, medical doctors and the paperback book industry advocating high-protein and fat- laden diets are grabbing the attention of millions of desperate people. “Lose 20 pounds in 30 days!” “Eat all the bacon you want and be thin as a breadstick!” The truth about these types of fad “diets” is that people can temporarily lose large amounts of weight, and can even lower their blood cholesterol, sugar, and triglycerides — but the method is unhealthful.

The only study published on the most popular high-protein diet, Dr. Atkin’s diet, shows the cholesterol goes up and LDL “bad” cholesterol goes up significantly, and HDL “good” cholesterol goes down significantly in women. Free fatty acids levels, which when elevated are associated with heart arrhythmias, are doubled. (J Am Diet Assoc 77:264 – 270, 1980).

Hyperinsulinism and Insulin Resistance

Advocates of high-protein diets explain the reason people are fat is not because of the fat they eat, but because of hyperinsulinism and insulin resistance. Insulin, the major regulator of fuel storage and release, is synthesized by the pancreas and secreted into the blood stream after we eat. Insulin stimulates the synthesis of fat, proteins, and glycogen (the storage form for sugars). It encourages fat cells to store fat and prevents the release of fat from these cells. Therefore, high levels of insulin, known as hyperinsulinism, would be expected to promote obesity. Eating simple sugars (including too much fruit), flours, and drinking alcohol stimulate insulin production and release. Eating all kinds of fat raises insulin levels (Diabetes Care 16:1459, 1993; Am J Clin Nutr 73:878, 2001). Exercise, eating whole grains, and small frequent meals (grazing), as opposed to gorging, lower insulin levels. Eating less food and a high-protein, low-carbohydrate diet can also lower insulin levels (Int J Obes Relat Metab Disord20:1067, 1996).

One of the greatest distortions of the truth promoted by high-protein diet advocates is that protein causes little or no increase in production of insulin. However, research shows just the opposite. When fed in equal amounts (calories), beef raises insulin more than whole grain pasta, cheese more than white pasta, and fish more than porridge (Am J Clin Nutr 66:1264, 1997). Maybe as important is the fact that carbohydrates are very satisfying for our hunger drive. Potatoes produce twice the level of appetite satisfaction as beef or cheese (Eur J Clin Nutr 49:675, 1995).

Insulin resistance is one of the reasons for hyperinsulinism. This condition is strongly associated with obesity; and in general the fatter you become the more insulin resistance you will demonstrate, for one important reason. Insulin resistance is an adaptation that keeps fat people from becoming even fatter — reducing the effectiveness of the insulin molecules causes less efficient fat storage. The underlying cause is the high-fat, high-sugar American diet, lack of physical exercise, and resulting obesity (Cent Eur J Public Health 7:122, 1999). However, recent research suggests that it is really the diet that causes insulin resistance and hyperinsulinemia rather than the resulting obesity being the cause (J Appl Physiol 84:1311, 1998).

Restoring Your Metabolism

The healthiest way to reduce insulin resistance and lower insulin levels is with a diet high in complex carbohydrates and low in fat, and exercise — this approach corrects the underlying causes of the resistance. In 1992, James Barnard published a study on the effects of a high complex carbohydrate diet and exercise on hyperinsulinemia (Am J Cardiol, 69:440, 1992). After three weeks, insulin levels in adult-type diabetics and people identified with insulin resistance were reduced by one-third. This study also showed a significant reduction in blood pressure (6/8 mm Hg), triglycerides (26%), cholesterol (22%) and weight (body mass index — 4%).

The “Ketogenic” High-Protein Diets

There are two kinds of high-protein diets popular today: Those that limit calorie intake by causing the body to develop a metabolic state known as ketosis; and those that make stringent rules which limit the dieter’s intake of food.

The “ketogenic diets” cause the body to produce ketones by severe restriction of carbohydrate intake while allowing unlimited fat and protein intake. With insufficient intake of the body’s primary fuel, carbohydrate, the body turns to fats from foods and from body fat for fuel. Byproducts of this metabolism are acidic substances called ketones (acetacetic acid, B-hydroxybuteric acid, and acetone). The metabolic condition is known as ketosis. Ketosis is associated with loss of appetite, nausea, fatigue, and hypotension (lower blood pressure). The result is a decrease in food (calorie) intake. Ketosis is the key to the diet’s success, by allowing the body to starve while reducing the suffering of severe hunger pangs.

This same condition, ketosis, occurs naturally when people are literally starving to death or seriously ill. During starvation this metabolic state is a kindness of nature allowing the victim to suffer much reduced pains of hunger while dying. During illness the suppression of the appetite frees the person to rest and recuperate, rather then be forced by hunger to gather and prepare food. Because ketogenic diets simulate this metabolic state seen with serious illness, I refer to them as “the make yourself sick diets.” As we will see below, another reason low-carbohydrate, high-protein diets deserve this title is they contain significant amounts of the very foods — the meats — that the American Cancer Society and the Heart Association tell us contribute to our most common causes of death and disability.

Initial Rapid Weight Loss

The initial weight loss is rapid, and therefore very rewarding, for the desperate dieter. Most of this loss, however, is water loss, rather than fat loss. With little carbohydrate in the diet the body resorts to using its glycogen stores of glucose. Glycogen, stored in the liver and muscles, can meet the average person’s glucose needs for about 12 to 18 hours. With each gram of glycogen is stored 2.7 grams of water. The average body stores 300 grams of glycogen. Depletion of the body’s glycogen would result in an almost overnight weight loss of 1110 grams (37 ounces or over 3 pounds). The ketones also cause a strong diuretic effect on the kidneys, resulting in losses of large amounts of fluid. The carbohydrate ceiling for weight loss may be as low as 15 grams, depending on the individual. This is only 60 calories of carbohydrate, which means 1/3 of a baked potato, 1/3 cup of rice, or one orange daily could be your limit of carbohydrate intake in order to remain in sufficient ketosis to suppress your appetite.

The Second Phase of Weight Loss

People who manage to stay on high-protein diets also lose weight because these diets restrict carbohydrate calories such as fruits, vegetables, breads, cereals, and legumes. Think about Thanksgiving on a high-protein ketogenic diet. You can have turkey, ham, butter, mayonnaise, and sour cream; but you can’t have potatoes, yams, bread dressing, cranberry sauce, breads, corn on the cob, hot cider, or pumpkin pie. By eliminating so many foods from your diet, you automatically reduce your calorie intake, resulting in a negative calorie balance and therefore weight loss. Doris Bosnyack of San Bernardino says, “I stayed on it about 3 weeks. After a while I couldn’t eat; the taste of the food was terrible. I didn’t enjoy it — just meat, meat, meat. I wasn’t a big meat eater to begin with. I got constipated and lethargic. I looked terrible. I looked like someone ran over me. My eyes got sunken in and blackened. I just felt sick.”

As you reach your desired weight on these diets you are allowed more carbohydrate. A maintenance diet prescribes levels generally between 30 and 90 grams of carbohydrates daily. However, if you start to regain weight as would be expected as you leave the appetite-suppressing advantages of ketosis, then you must immediately go straight back to the strictest carbohydrate-restrictive diet.

However, living with ketosis gets old fast for most people. Any benefits are usually temporary because it is too unpleasant to be in a state of ketosis seen with sickness — so people go back to their old way of eating to feel better and to enjoy their diet more, and they regain their lost weight and then some. A telling example of this is Dr. Atkins, the most famous advocate of ketogenic diets, who admits to being 20 pounds overweight; however, my eyeball of the situation leads me to believe that he’s easily wearing 40 extra pounds of fat or more. (Since his cardiac arrest and near death experience in April 2002, he appears to have lost some weight – maybe he is now on the McDougall diet? See the June 2002 McDougall Newsletter for details on this event.)

Ketogenic Diets Are Not for Humans

I have had Dr. Atkins on my radio show twice in the past and there are only two things we could agree on: first, his patients are constipated (there is no dietary fiber in meat, fish, poultry, cheese, butter, or eggs); and second, all major health organization make dietary recommendations opposite to his approach. Major professional health organizations, including the American Heart Association, the National Cholesterol Education Program, and the American Cancer Society endorse a diet that is composed of 10% to 15% protein, 55% to 60% carbohydrates, and 25% to 30% fat. The Atkins Diet can be more than 80% protein or fat, and less than 6% carbohydrate depending upon the low-carbohydrate foods selected. High-fat, high-protein diets are believed to be the underlying cause of our major diseases, including heart disease, strokes, adult-type diabetes, and obesity. In a report in the October 9, 2001 issue of the journal Circulation, the Nutrition Committee of the American Heart Association wrote “High-protein diets may also be associated with increased risk for coronary heart disease due to intakes of saturated fat, cholesterol, and other associated dietary factors” (Circulation 104:1869, 2001). “High-protein diets are not recommended because they restrict healthful foods that provide essential nutrients and do not provide the variety of foods needed to adequately meet nutritional needs. Individuals who follow these diets are therefore at risk for compromised vitamin and mineral intake, as well as potential cardiac, renal, bone, and liver abnormalities overall.”

Dr. Atkins recommends you eat all you can eat of roast rack of lamb, lobster dripping in butter, and bacon and eggs. He believes human beings are carnivores — an observation contradicted by all aspects of our anatomy and physiology. Our teeth are not like a cat’s, we have no claws for tearing apart meat, our intestine is designed for digesting plant foods, not meat, and our livers have a limited capacity to metabolize cholesterol, which is one big reason our cholesterol levels rise on the Western diet.

Food-restricting High-protein Diets

The second form of high-protein diets employs stringent rules for choosing foods in order to limit calorie intake. For example, The Zone Diet asks you to limit your protein intake to about 100 grams a day of protein, then distribute the rest of the calories as 30% protein, 30% fat, and 40% carbohydrate. Following these rules a man would be eating about 1300 calories a day, when he actually needs 2300 calories a day. You’re not supposed to feel hunger because you are in “the Zone” of properly-balanced insulin levels – right!

The Carbohydrate Addicts Diet reduces your calorie intake by asking you to eat two severely carbohydrate-restricted meals and one well-balanced “Reward Meal” containing carbohydrates (limited to one hour of eating). The carbohydrate-restricted meals severely limit your food choices to meats, poultry, fish, oils and most high-fat dairy products; as a result you take in fewer calories.

The Reward Meal has been modified over the years from 1991, when “All foods are allowed on the Reward Meal and quantities are not limited” with unlimited amounts of alcohol; to 1999, when a Reward Meal begins with two cups of fresh salad followed by equal portions of 1/3 protein, 1/3 low-carbohydrate vegetables, and 1/3 high-carbohydrate foods, and modest amounts of alcohol.

Is It the Fat or the Carbohydrates?

The resurgence of high-protein diets is based primarily on the misconception that carbohydrates alone induce weight gain. Actually the fat in the American diet is the biggest culprit. Fat is already in the chemical form for storage and is almost effortlessly moved from the fork and spoon to the body’s fat cells (costing only 3% of the calories of the fat). In fact, this transfer is performed so easily that the chemical structure of the dietary fat remains largely unchanged as it is stored; so that chemically analyzed body fat reflects a person’s diet. If one eats large amounts of cold-water fish then the body fat is filled with omega-3 fats, and margarines and shortenings result in the storage of trans fats. To convert carbohydrate into fat is expensive, costing 30% of the calories, and therefore this conversion is relatively limited on the Western diet (Ann N Y Acad Sci 819:44, 1997).

Carbohydrates in their simple and refined forms do raise insulin levels and as a result when combined with fat, as they are on the Western diet, they promote obesity. One definite improvement in the diet made by advocates of the low-carbohydrate regimes is their consistent recommendation to avoid sugar, white flour, milk, ice cream, cakes, pies, soft drinks, and low-fat diet products which contain large amounts of highly-refined carbohydrates. Also to their credit they all do recommend a high intake of healthful green and yellow vegetables, like asparagus, cauliflower, and onions. But they fail the dieter by restricting healthful complex carbohydrates, like rice, corn, beans and potatoes, and by recommending butter, eggs, meats and other very high-fat, high-cholesterol, and/or high-protein foods.

Osteoporosis and kidney stones are caused primarily by a diet rich in animal foods. Such a diet provides an abundance of acid that must be neutralized in order for the body to function properly and health to be maintained. The body’s primary buffering system is its bones. The bones dissolve as the first step to osteoporosis. The second step involves changes in the kidneys’ physiology caused by animal foods that results in the loss of this bone material into the urinary system. During its passage through the ureters some of the calcium solidifies into calcium kidney stones and the rest is lost from the body, leaving the bones porous (J Nutr 128:1051, 1998; J Pedriatr 117.743, 1990).

Mental Function Impaired by Ketosis

Mental health seems to be impaired by ketosis. Performance on the “Trail-making Task,” a neuropsychological test which requires higher order mental processing and flexibility was found to be adversely affected by the ketogenic diet (Int J Obes Relat Metab Disord 19:811, 1995). Maybe this reduced mental capacity is one reason some people on the Atkins Diet profess to feeling so great.

Val Johnson of Lakeland, Florida, summarizes his experiences on a ketogenic diet: “Our family doctor recommended the Atkins Diet to us. We got on it and we got sick, especially when we followed the bacon recommendation, where he says you can eat all the bacon you want. We stayed on the diet a week and a half. I believe the diet affected my thinking. I made some real bad mistakes on the job. One of them cost me a considerable amount of money. The most costly was when I ordered ¾ inch pipe when the customer wanted 1 ½ pipe, and it was a large order. It did cloud my thinking. I felt lethargic and slow and wasn’t mentally alert on my job.”

Lowering Risk Factors by Not Eating

So how do authors of ketogenic diets claim their diet will improve your health? This is based mostly on the observation that hyperinsulinism is corrected and that this condition is associated with atherosclerosis, high blood pressure, and diabetes. Hyperinsulinism is a risk factor, like blood sugar, cholesterol, triglycerides, blood pressure, and body weight. The important word here is “risk factor.” The actual disease these risk factors are predicting is rotten arteries (atherosclerosis). On a ketogenic diet, blood cholesterol, sugar, and triglycerides may be reduced because dieters are eating much less, as a result of loss of appetite and sometimes nausea caused by the ketosis. This only proves you can cause your risk factors to decrease by harmful treatment of your body. Here is a similar example: cancer chemotherapy will cause a loss of appetite, decrease in food intake, with resulting weight loss, lowered cholesterol and triglycerides (Biochem Int 24:1015, 1991). No one would consider these toxic drugs a healthful approach to lowered risk factors and fat loss.

The Natural Way to Permanent Weight Loss

There is a simpler, more healthful answer to obesity: eat the foods that thin people around the world eat; for example, the healthy people of Asia who thrive on high-carbohydrate, rice-based diets. The Japanese eat a diet abundant in rice and vegetables with only small amounts of animal protein and have a very low incidence of heart disease, breast, colon and prostate cancer and the world’s greatest longevity. Many Seventh-Day Adventists are strict vegetarians, who consume mainly grains, legumes, fruits, and vegetables, and as a result have a lower incidence of heart disease and colon cancer compared to the general population (Am J Clin Nutr 48:833, 1988; Cancer Res 35:3513, 1975). A recent (2001) study of Seventh Day Adventists found they lived longer and healthier. The vegetarian men and women had some of the best results with an expected age of death at 83.3 and 85.7 years, respectively. That is 9.5 and 6.1 years longer than the average Californian lives (Arch Intern Med 161:1645, 2001).

A diet based on complex carbohydrates with the addition of fruits and vegetables will cause effortless, permanent, healthful weight loss without restricting food or causing hunger. You eat delicious dishes such as minestrone soup, chili, and bean burritos. And you won’t ever have to make yourself sick again with fried cheese cubes wrapped in bacon.

John McDougall, MD

Brief History of High-Protein Diets

  • The first known diet book was published in 1864 by an English casket-maker, William Banting, after he became alarmed because he could no longer tie his shoes and had gotten so fat he had to walk down the stairs backward. His book, Letter of Corpulence, called for low-carbohydrate foods and daily alcohol, and sold 58,000 copies.
  • In 1961, Herman Taller wrote Calories Don’t Count, which sold two million copies and was against carbohydrates and sugar.
  • In 1967, Irwin Stillman published The Quick Weight-Loss Diet and sold 20 million copies of his high-protein, low-carbohydrate diet.
  • In 1972, Robert Atkins published his version of the high-protein low-carbohydrate diet, The Diet Revolution.
  • In 1978, the national bestseller, The Scarsdale Diet, advocating a 700-calorie, high-protein diet, was published.
  • In 1992, Atkins reissued his book as The New Diet Revolution.
  • Between 1991 and the present there has been one other successful ketogenic diet, Protein Power.
  • Other currently popular high-protein, non-ketogenic diets such as The Carbohydrate Addicts Diet, Sugar Busters!, Enter The Zone, The Schwarzheim Principle, and Suzanne Somers’ Get Skinny on Fabulous Food, simply restrict your calorie intake by various concocted rules based on little or no science.