The effect of graded intake and balance levels of exercise on energy in free-living women

AIM: We assessed the effect of graded increases in exercised-induced energy expenditure (EE) on appetite, daily energy intake (El), total daily EE and body weight in six lean women using a within-subject, repeated measures design. METHOD: Subjects were each studied three times during 7 day treatments, corresponding to no-exercise (control; Nex; 0 MJ/day), medium exercise level (Mex; similar to 1.9 MJ/day) and high exercise level (Hex; similar to 3.4 MJ/day), with 2 day maintenance beforehand. Subjects self-weighed ad libitum food intake. EE was assessed by continual heart rate monitoring. During waking hours subjects recorded hourly sensations of hunger and appetite. RESULTS: EE amounted to 9.2, 11.0 and 12.1 MJ/day (F (2, 10) = 5.67; P = 0.023 (s.e.d. = 0.87)) on the Nex, Mex and Hex treatments, respectively. The corresponding values for El were 8.9, 9.2 and 10.0 MJ/day (F (2, 10) = 4.80; P = 0.035 (s.e.d. = 0.36)). There were very weak treatment effects on hunger. Weight loss was significantly different from zero on the Mex and Hex treatments. CONCLUSION: Markedly increasing EE through exercise produced significant but partial compensations in El (similar to 33% of EE due to exercise). Accurate adjustments of El to acute increases in EE are likely to take weeks rather than days.