Atkins Diet: Why It Works and Its Limits

Chapter summary

Atkins is a low-carbohydrate diet with a plan, cookbooks, packaged products and many followers. One in eleven Americans used it in 2003/04.
Dr Robert Atkins was a cardiologist and a failed dieter. In 1958 he read a paper called “Weight Reduction” and lost weight on it. He then used the approach with patients.
The establishment shunned it, but his book sold widely.
The author’s verdict: given what we know about insulin, fructose, protein and fat, Atkins “pretty much has it right”. Cut sugar and simple carbohydrates and eat more protein and fat.

Induction (two weeks): 20g of carbohydrate a day. Expect a loss of 2 to 4kg.
Ongoing weight loss: Add 5g of carbohydrate a day each week until you find your critical level, usually 25 to 50g, losing 0.5 to 1.2kg a week.
Pre-maintenance: With 2 to 4kg left, add 10g a week and slow to under 0.5kg a week.
Lifetime maintenance: Keep to the carbohydrate level that holds your weight.

The Stanford A to Z study (Gardner 2007) compared Atkins, Zone, Ornish and LEARN diets in 311 overweight pre-menopausal women over 12 months.
Atkins weight loss was 4.7kg, about twice the 2kg of the other diets. HDL cholesterol, triglycerides and blood pressure also improved more. Attrition was 20%.
Insulin resistance matters. Women with insulin resistance did far better on low carbohydrate. If you are overweight with metabolic syndrome or type 2 diabetes, this diet beats a low-calorie one.

Early theories: Fat burns less efficiently, or you lose calories in urine, or ketosis burns extra energy. None held up.
Protein fills you up: Astrup’s study showed a high-protein group lost almost double the weight, because they ate fewer calories with free access to food.
Fructose cut: The first two weeks mirror cutting added sugar. Prepared foods carry hidden sugar, so cutting carbohydrates cuts fructose too.
Adherence: What you eat matters less than how long you keep doing it.
The criticism (Taubes on the Foster trial): Many trials compared a calorie-restricted low-fat diet with an unrestricted low-carb one, so the comparison is unfair. Critics ask whether calories alone decide weight. The data show people simply eat less on the low-carb diet.

Atkins focuses on weight and assumes less weight means better health. All health issues need attention.
Experts are not sure it works over the long term.
Costs fall mid-range, with meat and cheese pricey compared with cheap high-carb foods.
Most people need to keep carbohydrate under about 90g a day, one third of what many nutritionists suggest.

If Atkins works for you, use it. A sugar-free diet gets much the same result for the same reasons.

Pennington, A. (1958) Weight Reduction. JAMA.
Gardner, C. et al. (2007) Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors. JAMA 297:969-77.
Gardner, C. et al. (2008) Insulin resistance as an effect moderator of weight loss success on high vs. low carbohydrate diets. Obesity 16:S82.
Alhassan, S. et al. (2008) Dietary adherence and weight loss success among overweight women: A TO Z weight loss study. Int J Obes.
Skov, A. et al. (1999) Randomized trial on protein vs carbohydrate in ad libitum fat reduced diet. Int J Obes 23(5):528-536.
Volek, J. (2011) A calorie is a calorie… or is it.