Do High-Protein, Low-Carbohydrate Diets Work?

By: Joshua J Stone, MA, ATC, NASM-CPT, CES, PES

The Atkins diet made headlines in November 2002 when researchers from Duke University presented results of a study comparing the Atkins diet to the American Heart Association’s (AHA) low-fat diet at the AHA’s annual scientific meeting. Headlines of “Atkins diet meets with success,” “Vindication for the Atkins diet?” and “Atkins diet beats low-fat fare” had meat-lovers cheering and dietitians cringing. Skeptics argued that the study, funded by the Atkins Center for Complementary Medicine, included too few people and failed to monitor participants’ actual food intake and exercise levels.

Since this report, several studies of low-carbohydrate diets have been published, some of which were funded by government sources. One study compared a low-carbohydrate (30 grams per day) diet to a calorie-restricted, low-fat diet (30 percent of calories from fat; caloric restriction of 500 kcal per day) for severely obese adults (1). The study lasted six months and included 132 total subjects. In the other study, 63 obese adults were randomly assigned to either a low-carbohydrate, high-protein, high-fat diet (based on the Atkins diet) or a low-calorie, high-carbohydrate, low-fat diet (60 percent carbohydrate, 25 percent fat, 15 percent protein) (2). Subjects were followed for a one-year period.

At the six-month time point in both studies, people on the low-carbohydrate diets had lost more weight (about 8 pounds more on average). When the subjects were followed for one year, however, difference in weight loss became nonsignificant. Overall weight loss was relatively small compared with the participants’ starting weights. Improvements in blood cholesterol levels initially seen on the low-carbohydrate diet also became nonsignificant as time progressed. In both studies, drop-out rates were high—about 60 percent of those who began the studies. This attrition rate makes interpretation of the results difficult, if not impossible (3). A review of published studies concluded that participant weight loss on low-carbohydrate diets was mainly associated with decreased calorie intake rather than reduced carbohydrate content (4).

In another study that compared four different types of popular weight-loss diets, overall weight loss at one year was similar regardless of diet (5). Heart disease risk factors improved for each diet group, but in different ways. The very low fat vegetarian Ornish diet was best for lowering LDL cholesterol, where as other diets, including Atkins and the Zone, were better at raising HDL cholesterol.

So what explains reports of dramatic weight loss and no hunger while eating pork rinds, bacon, sausage, and steak? Removing carbohydrates from the diet causes the body to deplete glycogen stores, which results in a rapid loss of water. The ketosis that results from low carbohydrate intake can also enhance fluid loss. High protein intake tends to be satiating, and the monotony of the diet also blunts the appetite. Although the effects are small, an increase in protein intake (e.g., 30 to 35 percent of calories) causes a slight increase in energy expenditure, possibly from the extra energy needed to convert protein to glucose (6).

Are High-Protein, Low-Carbohydrate Diets Safe?

In a review of research on low-carbohydrate diets, Levine and colleagues found insufficient evidence to recommend for or against this approach to weight loss (7). They note that common concerns include accumulation of ketones, abnormal insulin metabolism, impaired liver and kidney function, salt and water depletion, impaired renal function, and hyperlipidemia resulting from high fat intake. Their analysis of weight outcomes and complications was limited by small sample sizes, high drop-out rates, short study durations, and high variability in measured outcomes. It is likely, though, that people who start a low-carbohydrate diet do not stay on it long enough to develop serious complications, although constipation, nausea, weakness, dehydration, and fatigue are common side effects.

The Best Diets to follow

Is there a “best” diet? If there were, we wouldn’t have so many diet books vying for our attention and money! What we know about our nutrient needs still points to the Dietary Guidelines for Americans for guidance: the best diet emphasizes fruits, vegetables, and grains—not high-protein foods. From what we have seen in research studies, it is very difficult for individuals to stick to a particular diet, especially those diets that are most restrictive (8). And although weight loss may be the goal of many, weight maintenance is the key to reducing the health risks of obesity. Weight maintenance requires permanent changes to eating habits and, more important, increased physical activity. The specific strategies for making those changes, and making them permanent, will vary from person to person. So, instead of a walk through the diet book aisle, save your money and improve your health with a fitness walk through the mall.

  1. Samaha FF, Iqbal N, Seshadri P, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med. 2003;348:2074–2081.
  2. Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. 2003;348:2082–2090.
  3. Ware JH. Interpreting incomplete data in studies of diet and weight loss. N Engl J Med. 2003;348:2136–2137.
  4. Bravata DM, Sanders L, Huang J, et al. Efficacy and safety of low-carbohydrate diets: a systematic review. JAMA. 2003;289(14):1837–1850.
  5. Dansinger ML, Gleason JA, Griffith JL, et al. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005;293:43–53.
  6. Buchholz AC, Schoeller DA. Is a calorie a calorie? Am J Clin Nutr. 2004;79(suppl):899S–906S.
  7. Levine MJ, Jones JM, Lineback DR. Low-carbohydrate diets: assessing the science and knowledge gaps, summary of an ILSI North America workshop. J Am Diet Assoc. 2006;106:2086–2094.
  8. Dansinger, Gleason, Griffith, et al. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets.

Taken from:

Insel, P. Ross, D., McMahon, K and Berstein, M. “High Protien, Low Carbohydrates Diets for Weight Loss: Helpful or Harmful?”  in Nutrition. PP 368-369. 4th Ed. Jones and Bartlett Publishers: Boston, 2011

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  1. October 25, 2012 at 9:01 pm — Reply

    YES -Atkins Diet (FAILED)YES -Weight Watchers (FAILED)NO -Slimb7Fast Optima DietNO -Sugar BustersNO -South Beach DietYES Calorie Restricted Diet (FAILED)YES Whole Plant Based Diet (THE WINNER)NOTE:The only diet that worked for me was a diet cealld a low-fat whole plant based diet that has been endorsed by Dr. Dean Ornish, Dr. Neal Barnard, Dr. Joel Fuhrman, Dr. John McDougall, and Professor T. Colin Campbell. Read any of these outstanding biochemists and nutrition experts for details. If you read Gina Kolata’s book Rethinking Thin you will learn that over the long-term, none of the commercially popular diets worked for most people. People, even those who are highly motivated, cannot stay on these diets because they are temporary and cannot be sustained.I will answer the following questions with regard to a Whole Plant Based diet as described by Dr. Caldwell Esselstyn, Jr.1.Why did you initially choose this diet?At a dinner party, a distinguish retired physician pulled me aside and expressed concern for my health because of my excess weight. As an active triathelete, he had instant credibility. He recommended that I read Dr. Dean Ornish. I started the diet, the next day. Since that day, I moved through the authors I listed above who recommend essentially the same diet.2.What is the basic premise of this diet/eating plan?Avoid food like substances that are over processed. Avoid excess sugar, fat/oil, salt, caffeine, alcohol, refined carbohydrates, MSG, aspartame, drugs, food contaminants, food additives, dairy, eggs, and all other forms of animal protein. Instead eat the following foods:+ Leafy greens Kale, Collards High in iron, calcium, and protein.+ Legumes Peas, Beans, Lentils Bean sprouts are delicious and nutritious+ Whole Grains Brown Rice, Buckwheat, and non-gluten whole grains (not instant and overprocessed)+ Colorful Vegetables Steamed and raw+ Vitamin B12 and D as needed+ Ground Flax Seed for Omega-3 Essential Fatty Acids (avoid all other fats and oils)+ Drink pure well water avoiding municipal water supplies treated with chlorine and fluoride3. What were two positive aspects of the diet?+ This is a lifestyle change and the motivation to stay on the diet is built in. It’s how good you feel.+ No calorie counting+ No feeling of deprivation+ Prevention and reversal of cardiovascular disease and diabetes. (Dr. Caldwell Esselstyn, Jr.)+ Blood work is automatically moved toward health4.Were there any downsides to the diet plan? Explain.It requires that you learn how to cook and not use some common ingredients. Eating out can be a problem, but you can find ethnic restaurants that serve healthier foods.5.Did you have success on this diet?Yes. I lost 90 pounds, regained my sense of smell, no longer have sinus infections, and have perfect blood work.6.Are you still on the diet plan?It’s my new lifestyle, not a temporary diet.7.Have you maintained your weight loss?Yes. I am now moving on to portion control. I plan to eat just two meals per day. A big breakfast and an afternoon meal.8.Do you feel the diet is safe? Why or why not?It is absolutely the safest and healthiest way to eat. The authors and experts I cited above are independent of food industry interests. The diet is optimal for everyone, skinny or fat.9.Did you exercise while on the diet?I exercise aerobically five times per week for an hour at a time. I bicycle to work every day.10.Would you follow this diet plan again?It’s the only diet for me. If you diet for a temporary period of time, you can be assured that the weight will rebound. You must make the diet a lifestyle choice.

    • November 18, 2012 at 5:42 am — Reply

      It depends on your wehigt. If you only have a few pounds to lose, like 10-15, then it’ll take longer to lose that amount than if you have over 20 pounds to lose. With the HCG drops, I’m guessing you could lose 7 pounds easy. More if you’re really strict while on the VLCD. Remember you only eat 500 calories a day, no sugar (nor fake sugars like splenda), 200 grams of meat total, 2 fruits, and 1 bread thing. If you want to lose the wehigt faster, you may want to cut out the bread stick and 1 of the fruits. Honestly, I started these drops 4 days ago (2 days of Phase 1, and now I’m on my second day of Phase 2) and I just got on the scale a few minutes ago and I lost 5 pounds in 1 day! But I have quite a bit of wehigt to lose so that won’t be the results for everyone. If you exercise at least 30 minutes a day also, you could lose even more than 10 pounds a week. Also, I haven’t been hungry on this diet. The drops help soo much! Good luck and have fun in N. Carolina!

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