Short-term dietary energy restriction reduces lean body mass but not performance in physically active men and women.
We studied the effect of moderate, short-term energy restriction on physical performance in physically fit men (n = 13) and women (n = 11) in a controlled clinical research setting with a metabolic kitchen, exercise testing laboratory and training facility. The experiment consisted of a 10 d baseline period followed by either 2 wk of dietary energy restriction (750 kcal/d; n = 16) or energy balance (control; n = 8). During this 24 day study, exercise energy expenditure averaged 465 +/- 5.7 kcal/d in all subjects and was accomplished through treadmill running at a self-selected pace. Body weight was maintained in the control group (-0.36 +/- 0.24kg), but energy restriction resulted in weight loss of -1.29 +/- 0.16 kg (p < 0.001). There was a trend for lean body mass to decline more in the energy restriction group (p = 0.093), accounting for 61% of the weight loss, and urinary nitrogen excretion also tended to be higher in the energy restriction vs. control group (i.e., 13.2 +/- 1.1 vs. 11.2 +/- 1.0g/d; p = 0.089). Muscle strength (leg & shoulder press; 1 repetition maximum) was maintained or increased during the energy restriction period. Muscle endurance, assessed by leg squats to fatigue, and 5 mile run time improved following two weeks of energy restriction or balance. Anaerobic capacity (Wingate Test) increased slightly in the restriction (+ 368 +/- 219 joules) but declined in the control group 649 +/- 288 joules; p<0.05). We conclude that short-term (2 weeks) moderate energy restriction (approximately 750 kcal/d) results in weight loss but does not impair performance in physically fit young men and women.
Zachwieja
J J
JJ
Exercise and Nutrition Program, Pennington Biomedical Research Center, Baton Rouge, LA, USA. jeff_zachwieja@quakeroats.com
Ezell
D M
DM
Cline
A D
AD
Ricketts
J C
JC
Vicknair
P C
PC
Schorle
S M
SM
Ryan
D H
DH
D000328:Adult; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D002149:Energy Intake / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009584:Nitrogen / Q000652:urine; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance; D010809:Physical Fitness / Q000502:physiology*; D012107:Research Design; D013177:Sports / Q000502:physiology*; D013647:Task Performance and Analysis; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*
D009584:Nitrogen