Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating.
Researchers used a single-blind, randomised controlled trial of 25 American healthy, weight-stable male and female volunteers, aged 18 - 35 years, with a body mass index between 19 and 30. The first participant was admitted to the inpatient metabolic unit in June 2005 and the last in October 2007.
After consuming a weight-stabilising diet for 13 - 25 days, participants were randomised to diets containing 5% of energy from protein (low protein), 15% (normal protein), or 25% (high protein), which they were overfed during the last 8 weeks of their 10 - 12-week stay in the inpatient metabolic unit. Compared with energy intake during the weight stabilisation period, the protein diets provided approximately 40% more energy intake, which corresponds to 954 kcal/d (95% CI, 884 - 1 022 kcal/d).
Body composition was measured by dual-energy X-ray absorptiometry bi-weekly, resting energy expenditure was measured weekly by ventilated hood, and total energy expenditure by doubly labelled water prior to the overeating and weight stabilisation periods and at weeks 7 - 8.
Overeating produced significantly less weight gain in the low-protein diet group (3.16 kg; 95% CI, 1.88 - 4.44 kg) compared with the normal-protein diet group (6.05 kg; 95% CI, 4.84 - 7.26 kg) or the high-protein diet group (6.51 kg; 95% CI, 5.23 - 7.79 kg) (p=0.002). Body fat increased similarly in all 3 protein diet groups and represented 50% to more than 90% of the excess stored calories. Resting energy expenditure, total energy expenditure, and body protein did not increase during overfeeding with the low-protein diet. In contrast, resting energy expenditure (normal-protein diet: 160 kcal/d (95% CI, 102 - 218 kcal/d); high-protein diet: 227 kcal/d (95% CI, 165 - 289 kcal/d)) and body protein (lean body mass) (normal protein diet: 2.87 kg (95% CI, 2.11 - 3.62 kg); high-protein diet: 3.18 kg (95% CI, 2.37 - 3.98 kg)) increased significantly with the normal-and high-protein diets.
Among persons living in a controlled setting, calories alone account for the increase in fat; protein affected energy expenditure and storage of lean body mass, but not body fat storage.
Bray GA, et al. JAMA 2012;307(1):47-55. doi: 10.1001/jama.2011.1918.
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|Publication:||CME: Your SA Journal of CPD|
|Date:||Feb 1, 2012|
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