Energy compensation in response to aerobic exercise training in overweight adults

Authors: Flack, Kyle; Ufholz, Kelsey; JOHNSON, LUANN - University Of North Dakota; FITZGERALD, JOHN - University Of North Dakota; Roemmich, James

Submitted to: American Journal of Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2018
Publication Date: 9/13/2018
Citation: Flack, K.D., Ufholz, K.E., Johnson, L., Fitzgerald, J.S., Roemmich, J.N. 2018. Energy compensation in response to aerobic exercise training in overweight adults. American Journal of Physiology. https://doi.org/10.1152/ajpregu.00071.2018.
DOI: https://doi.org/10.1152/ajpregu.00071.2018

Interpretive Summary: Background: Often, exercise does not produce the amount of weight lost that people expect. This may be due to compensatory responses when people start exercising such as eating more and reducing the amount of activity that the do outside of exercise. This could result in little weight loss. Scientists at the Grand Forks Human Nutrition Research Center determined how people compensated when exercising either 1500 or 3000 kcal/week. They found that exercising 3000 kcal/week decreased body fat while exercising 1500 kcal/week did not reduce weight or fat. Both the 1500 and 3000 kcal/week groups either increased their eating and/or reduced their activity by a total of about 950 kcal/week, or about 63% and 33% of the energy expended during exercise. So, compensation is not proportional to the amount of energy expended during exercise. Nearly the same total amount of energy compensation occurred when exercising 1500 kcal/week and 3000 kcal/week. Exercising to expend 3000 kcal/week should be great enough to reduce body fat.

Technical Abstract: Background: The amount of weight lost by exercise training is often less than expected. Compensatory responses such as increased energy intake and reduced non-exercise energy expenditure may limit exercise-induced reductions in body weight and might be proportional to exercise energy expenditure. This could produce little difference in weight loss between small and great amounts of exercise energy expenditure. Purpose: To determine compensation (difference between accumulated exercise energy expenditure and changes in body tissue energy stores) and biological and neurobehavioral compensatory responses to 1500 or 3000 kcal/week of exercise energy expenditure. Methods: Overweight to obese (n=36), sedentary men and women were randomized to groups expending either 300 or 600 kcal/exercise session, 5 days/week, for 12 weeks. Resting metabolic rate (RMR), food reinforcement, dietary intake, body composition, and serum acylated ghrelin and glucagon-like peptide-1 (GLP-1) were determined pre- and post-training. Results: The 3000 kcal/week group decreased (-2.62 kg, P<0.01) body fat while the 1500 kcal/week group (-0.82 kg) did not. The 1500 and 3000 kcal/week groups compensated 929 and 988 kcal/week (P=0.43), or 62.9% and 33.6% of exercise energy expenditure, respectively. RMR and energy intake did not change. Food reinforcement and GLP-1 decreased (P<0.02), while acylated ghrelin increased (P=0.02). Conclusion: Compensation is not proportional to exercise energy expenditure. Similar energy compensation occurred in response to1500 kcal/week and 3000 kcal/week of exercise energy expenditure across 12 weeks of training. Exercise energy expenditures of 3000 kcal/week are great enough to exceed compensatory responses and can reduce fat mass.