Dietary compliance + calorie deficit = success

Nicked from Anthony Colpo's site. Link: http://anthonycolpo.com/?p=4003

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With a career spanning 40 years, and having authored or coauthored over 1,700 publications, Dr. George Bray is definitely one of the heavy hitters in obesity research. As part of the POUNDS LOST trial, Bray teamed up with researchers from the Harvard School of Public Health, Brigham and Women’s Hospital, Pennington Biomedical Research Center in Baton Rouge, and the National Heart, Lung, and Blood Institute to examine the effects of varying protein:fat:carbohydrate ratios on weight loss[1].

For reasons that will become clear shortly, POUNDS LOST is not a study you’re likely to hear about from your favourite low-carb or low-fat shill.

The nutrient goals for the four diet groups were:

20% fat, 15% protein, and 65% carbohydrates (lowfat, average-protein);
20% fat, 25% protein, and 55% carbohydrates (low-fat, high-protein);
40% fat, 15% protein, and 45% carbohydrates (high-fat, average- protein);
40% fat, 25% protein, and 35% carbohydrates (high-fat, high-protein).

The trial was a free-living study.

Each participant’s caloric prescription recommended a deficit of 750 calories per day from baseline, as calculated from the person’s resting energy expenditure and activity level.

The goal for physical activity was 90 minutes of moderate exercise per week.

811 subjects began the study, and 645 of those assigned completed the trial.

The Results?

Weight loss after 2 years was similar in participants completing the 25% protein and 15% protein diets (4.5 and 3.6 kg, respectively; P = 0.11).

Weight loss was the same in those who completed the 40% fat and 20% fat diets (3.9 and 4.1 kg, respectively; P = 0.76).

There was no effect on weight loss of carbohydrate level through the target range of 35 to 65%.

The change in waist circumference did not differ significantly among the diet groups.

Most of the weight loss occurred in the first 6 months; after 12 months, all groups, on average, slowly regained body weight.

Craving, fullness, and hunger and diet-satisfaction scores were similar at 6 months and at 2 years among the diets.

But Wait, There’s More

In a follow-up study recently published in the American Journal of Clinical Nutrition[2], the researchers looked at whether the various diets differentially preserved lean mass or reduced total, visceral, or hepatic fat in a subset of 424 participants.

At 6 months, participants lost a mean 4.2 kg (12.4%) fat and 2.1 kg (3.5%) of lean mass, with no differences between the various diets.

Participants lost 2.3 kg (13.8%) abdominal fat: 1.5 kg (13.6%) subcutaneous fat and 0.9 kg (16.1%) visceral fat, with no differences between the diets.

Participants regained 40% of these losses by 2 years, with no differences between diets.

Weight loss reduced hepatic fat, but there were no differences between groups.

Being a free-living study, dietary goals were not fully met; self-reported contrasts were closer to 2% protein, 8% fat, and 14% carbohydrate at 6 months and 1%, 7%, and 10%, respectively, at 2 years. This underscores the inescapable fact that, while metabolic ward trials are true tests of diet, free-living studies are in effect examinations of dietary advice, something worth remembering next time your favourite low-carb guru wanks on about some cherry-picked free-living study that found greater weight loss for the low-carb group…

The only variable that seemed to impact weight loss was attendance at the scheduled group sessions; session attendance strongly predicted weight loss at 2 years (0.2 kg for every session attended) and was similar among the diet groups. This underscores what previous studies have found; that sticking to your diet is more important for weight loss than the actual type of diet. All successful weight loss strategies involve creation of a calorie deficit sufficient to induce weight, and most diet strategies include restriction of one or more food groups (ie low-fat, low-carb) which often provides an inbuilt calorie reduction mechanism (no matter what clueless authors and bloggers tell you, if you lost weight after trying some new diet, it’s only because you subsequently created a calorie deficit). Those who adhere to their diets most stringently are the ones who are most likely to achieve a calorie deficit and hence weight loss.

References

[1]Sacks FM, et al. Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates. NEJM, February 26, 2009; 360 (9): 859-873.
[2]de Souza RJ, et al. Effects of 4 weight-loss diets differing in fat, protein, and carbohydrate on fat mass, lean mass, visceral adipose tissue, and hepatic fat: results from the POUNDS LOST trial. AJCN, 2012; 95: 614–625.