Study Examines Effects of Calorie Restriction on Body Composition in Normal-Weight Women

A recent study found that in normal-weight women, caloric restriction and exercise resulted in less-than-predicted weight loss, but, in contrast to results of previous studies, weight that was lost consisted almost entirely of fat mass, and not fata-free mass.

For their study, researchers performed a secondary analysis of data from a randomized controlled trial that included 25 sedentary normal-weight women. Nine participants were randomly assigned to a severe energy deficit diet (−1062±80 kcal per day), 9 participants were assigned to a moderate energy deficit diet (−633±71 kcal per day), and 7 participants were assigned to an energy balance diet. All participants exercised 5 times per week for 3 months. Researchers assessed changes in body weight, body composition, resting metabolic rate (RMR), and metabolic hormones associated with energy conservation.
_________________________________________________________________________________________________________________________________
RELATED CONTENT
Study: Physical Activity Alone May Not Improve Weight Loss Efforts
Unrestricted Calorie, High-Fat Mediterranean Diet Linked to Greater Weight Loss Than Low-Fat Diet
_________________________________________________________________________________________________________________________________

“Weight loss occurred in SEV (-3.7±0.9 kg, P<0.001) and MOD (-2.7±0.8 kg; P=0.003), but weight loss was significantly less than predicted (SEV: -11.1±1.0 kg; MOD: -6.5±1.1 kg; both P<0.001 vs actual),” the researchers wrote.

“RMR decreased by −6±2% in [moderate energy deficit] (P=0.020). In [severe energy deficit], RMR did not change on a group level (P=0.66), but participants whose RMR declined lost more weight (P=0.020) and had a higher baseline RMR (P=0.026) than those whose RMR did not decrease.”

In addition, researchers observed that changes in leptin, tri-iodothyronine, insulin-like growth factor-1, and ghrelin occurred only in the severe energy deficit group.

“In normal-weight women, caloric restriction and exercise resulted in less-than-predicted weight loss. In contrast to previous literature, weight loss consisted almost exclusively of fat mass, whereas fat-free mass was preserved,” the researchers concluded.

—Melissa Weiss

Reference:

Koehler K, De Souza MJ, and Williams NI. Less-than-expected weight loss in normal-weight women undergoing caloric restriction and exercise is accompanied by preservation of fat-free mass and metabolic adaptations. Eur J Clin Nutr 71(3):365-371.