Effects of Dietary Composition During Weight Loss Maintenance: A Controlled Feeding Study

Context Many diets can produce weight loss over the short term, but the biological effects of dietary composition during weight loss maintenance have not been well studied. Objective To examine three diets differing widely in macronutrient composition and glycemic load following weight loss. Design and Setting Controlled feeding study with a three-way cross-over design conducted in major metropolitan area (June 2006 to June 2010), with recruitment by newspaper advertisements and postings. Participants Overweight and obese young adults (n=21). Interventions After achieving 10 to 15% weight loss on a run-in diet, participants consumed low-fat (LF; 60% of energy from carbohydrate, 20% fat, 20% protein; high glycemic load), low-glycemic index (LGI; 40%-40%-20%; moderate glycemic load), and very-low-carbohydrate (VLC; 10%-60%-30%; low glycemic load) diets in random order, each for 4 weeks. Main Outcome Measures Resting energy expenditure (REE, primary outcome), total energy expenditure (TEE), hormones, and metabolic syndrome components. Results The decline in REE (mean [95% CI]) with weight loss was greatest with the LF diet (−205 [−265 to −144] kcal/d), intermediate with the LGI diet (−166 [−227 to −106] kcal/d), and least with the VLC diet (−138 [−198 to −77] kcal/d; P=0.03, P for trend by glycemic load=0.009). The decline in TEE showed a similar pattern (LF: −423 [−606 to −239] kcal/d; LGI:−297 [−479 to −115] kcal/d); VLC: −97 [−281 to +86] kcal/d; P=0.003, P for trend=0.0009). Hormones and metabolic syndrome components also varied during weight maintenance by diet: leptin (P=0.0006); 24-hour urinary cortisol (P=0.005); indexes of peripheral (P=0.02) and hepatic (P=0.03) insulin sensitivity; HDL cholesterol (P<0.0001); non-HDL cholesterol (P=0.0005); triglycerides (P