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

Harvard University, Cambridge, Massachusetts, United States
American Journal of Clinical Nutrition (Impact Factor: 6.77). 03/2012; 95(3):614-25. DOI: 10.3945/ajcn.111.026328
Source: PubMed


Weight loss reduces body fat and lean mass, but whether these changes are influenced by macronutrient composition of the diet is unclear.
We determined whether energy-reduced diets that emphasize fat, protein, or carbohydrate differentially reduce total, visceral, or hepatic fat or preserve lean mass.
In a subset of participants in a randomized trial of 4 weight-loss diets, body fat and lean mass (n = 424; by using dual-energy X-ray absorptiometry) and abdominal and hepatic fat (n = 165; by using computed tomography) were measured after 6 mo and 2 y. Changes from baseline were compared between assigned amounts of protein (25% compared with 15%) and fat (40% compared with 20%) and across 4 carbohydrate amounts (35% through 65%).
At 6 mo, participants lost a mean (±SEM) of 4.2 ± 0.3 kg (12.4%) fat and 2.1 ± 0.3 kg (3.5%) lean mass (both P < 0.0001 compared with baseline values), with no differences between 25% and 15% protein (P ≥ 0.10), 40% and 20% fat (P ≥ 0.34), or 65% and 35% carbohydrate (P ≥ 0.27). Participants lost 2.3 ± 0.2 kg (13.8%) abdominal fat: 1.5 ± 0.2 kg (13.6%) subcutaneous fat and 0.9 ± 0.1 kg (16.1%) visceral fat (all P < 0.0001 compared with baseline values), with no differences between the diets (P ≥ 0.29). Women lost more visceral fat than did men relative to total-body fat loss. Participants regained ~40% of these losses by 2 y, with no differences between diets (P ≥ 0.23). Weight loss reduced hepatic fat, but there were no differences between groups (P ≥ 0.28). Dietary goals were not fully met; self-reported contrasts were closer to 2% protein, 8% fat, and 14% carbohydrate at 6 mo and 1%, 7%, and 10%, respectively, at 2 y.
Participants lost more fat than lean mass after consumption of all diets, with no differences in changes in body composition, abdominal fat, or hepatic fat between assigned macronutrient amounts. This trial was registered at as NCT00072995.

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Available from: Meryl S Leboff, Oct 04, 2015
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    • "Furthermore, increasing dietary protein can help maintain SkM mass during periods of disuse (reviewed in Wall & van Loon, 2013) and induce greater increases in skeletal muscle hypertrophy following chronic supplementation when combined with exercise (resistance) vs. exercise alone (meta-analysis Cermak et al., 2012). Indeed, there is substantial support to suggest that with DR, overall weight loss is no different with higher protein intakes vs. DR alone (Sacks et al., 2009; de Souza et al., 2012). With some acute trials showing that fat mass decreases while SkM is spared (Krieger et al., 2006), importantly, exercise in combination with higher protein content in DR diets seems to have a SkM maintaining effect (Garthe et al., 2011; Josse et al., 2011; Mojtahedi et al., 2011), without negative impact on markers of mitochondrial biogenesis, albeit after acute fasting in humans (Taylor et al., 2013). "
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    • "The percentage of participants with metabolic syndrome decreased after 2 y but, again, no difference was observed among groups. A second randomized trial conducted by de Souza et al. (26) in 2012 was designed to determine whether energyreduced diets that emphasized fat, protein, or carbohydrates differentially reduced total, visceral, or hepatic fat or preserved lean mass. Participants were randomly assigned to 4 weight loss diets. "
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    • "The operational definition of weight loss quality is loss of a high ratio of fat to lean tissue, with an emphasis on the loss of visceral fat [49]. Therefore, while general conclusions regarding weight loss in long-term free-living individuals have suggested that weight loss is no different with higher protein intakes [50, 51], short-term trials have shown important differences in the weight lost as fat with muscle ‘spared’ [48]. What is evident is that with respect to weight loss with exercise, higher protein and higher dairy protein in particular provide a protective effect for muscle, even allowing its accrual in certain circumstances [49, 52]. "
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