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The systematic review presented here assessed the effects of energy restriction (ER) and exercise (EX) on fat-free mass (FFM) in overweight and obese middle-aged and older adults. PubMed was searched using the key words 'weight loss or energy restriction' AND 'skeletal muscle or body composition,' with limitations set for 'human' and 'middle-aged and aged.' Results from 52 studies are reported as the percentages of EX (mainly aerobic training), ER, or ER+EX groups that had a specified change in body weight and FFM, since insufficient data were available for a meta-analysis. The EX groups had modest body weight and FFM changes. Eighty-one percent and 39% of the ER and ER+EX groups, respectively, lost [greater than or equal to] 15% of body weight as FFM. These findings suggest that exercise is an effective tool to help men and postmenopausal women aged [greater than or equal to] 50 years, with a BMI greater than 25 kg/[m.sup.2]preserve FFM after moderate ER-induced weight loss, which is important for combating sarcopenic obesity. Key words: aging, body composition, exercise, muscle loss, weight loss doi: 10.1111/j.1753-4887.2010.00298.x

Objective This controlled feeding study examined the effects of exercise on daily water intake (particularly ad libitum water intake), water output, whole-body water balance, and hydration status in physically active, premenopausal women. Design The randomized crossover design consisted of three 8-day trials: placebo and no exercise, placebo and exercise (1-hour cycling bout per day at 65%-70% of heart rate reserve), and 800 mg calcium supplementation and exercise. During each trial, controlled quantities of the same foods and beverages were provided and ad libitum water intake was quantified. Water input included measured water from foods and beverages, measured ad libitum intake, and estimated metabolic production. Water output included measured losses in urine and stool, and estimated insensible losses from respiration and non-sweating perspiration (insensible diffusion through the skin). Subjects Participants were 26 women, age 25 [+ or -] 5 years, body mass index 22 [+ or -] 2, and V[O.sub.2peak] 43 [+ or -] 6 mL x [kg.sup.-1] x [min.sup.-1] (mean [+ or -] standard deviation). Results Ad libitum water intake was 363 g/day more (P<0.05) for the placebo and exercise (1,940 [+ or -] 654 g/day) and calcium supplementation and exercise (1,935 [+ or -] 668 g/day) trials, compared with placebo and no exercise trial (1,575[+ or -] 667 g/day), and total water input was correspondingly higher in placebo and exercise and calcium supplementation and exercise trials compared with the placebo and no exercise trial. Urine, stool, and total water outputs were not different among trials. Apparent net water balance (representative of sweat water output) was 367 g/day more (P<0.05) in placebo and exercise (679 [+ OR -] 427 g/day) and calcium supplementation and exercise (641 [+ or -] 519 g/day) trials compared with placebo and no exercise trial (293 [+ or -] 419 g/day). Hydration status was clinically normal during all three trials. Calcium supplementation did not influence water balance. Conclusion These results support that young, physically active women can completely compensate for exercise-induced sweat losses by increasing ad libitum water intake, and not decreasing non-sweat water outputs or impairing hydration status.