Which Diet Works Best?

This question comes up quite frequently, and I’m going to stay away from answering it in terms of absolutes.  The notion that there’s one diet that works best for everyone is pretty ridiculous, so we just won’t go there.

With that said, there are a couple of studies that support my choice of a low-carb diet:

The second one I’ve covered previously here, so I won’t revisit it again except to say that the study provides pretty clear evidence of a distinct metabolic advantage to high fat, low carb diets.

The first study, commonly referred to as “The A-Z Study” or “The A-Z Diet Study” is one that we haven’t talked about, which is a shame.

The A-Z Diet study compares the following 4 diets against each other:

  • Atkins – “20 grams/day or less of carbohydrate for “induction” (usually 2-3 months) and 50 grams/day or less of carbohydrate for the subsequent “ongoing weight loss” phase.”
  • Zone – “40%-30%-30% distribution of carbohydrate, protein, and fat, respectively.”
  • LEARN – “55% to 60% energy from carbohydrate and less than 10% energy from saturated fat, caloric restriction, increased exercise, and behavior modification strategies.”
  • Ornish – “The primary emphasis for the Ornish group was no more than 10% of energy from fat.”

It consisted of a twelve-month randomized trial conducted in the United States from February 2003 to October 2005 among 311 free-living, overweight/obese (body mass index, 27-40) nondiabetic, premenopausal women.

I’ll quote the conclusions directly, as they are pretty damn clear:

Results  Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months, and mean 12-month weight loss was significantly different between the Atkins and Zone diets (P<.05). Mean 12-month weight loss was as follows: Atkins, −4.7 kg (95% confidence interval [CI], −6.3 to −3.1 kg), Zone, −1.6 kg (95% CI, −2.8 to −0.4 kg), LEARN, −2.6 kg (−3.8 to −1.3 kg), and Ornish, −2.2 kg (−3.6 to −0.8 kg). Weight loss was not statistically different among the Zone, LEARN, and Ornish groups. At 12 months, secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups.

Conclusions  In this study, premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight and experienced more favorable overall metabolic effects at 12 months than women assigned to follow the Zone, Ornish, or LEARN diets. While questions remain about long-term effects and mechanisms, a low-carbohydrate, high-protein, high-fat diet may be considered a feasible alternative recommendation for weight loss.

To review, Atkins, the low-carb diet, was the clear winner in terms of weight loss at 12 months.  Additionally, secondary measurements of health (including lipid profile, body fat percentage, fasting insulin, fasting glucose, and blood pressure) improved across the board for all diets, but were as good or better for the Atkins diet.

Lose more weight, better health. That’s why I chose low carb.


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