Our recent publication in the International Journal of Sport Nutrition and Exercise Metabolism examined whether athletes become less active when their food intake is restricted.
Energy availability (EA) is defined as the amount of dietary energy available to maintain physiological functions after training expenditure is subtracted from energy intake. When athletes or trained individuals have high energy expenditure with low energy intake, i.e., expending a lot of energy through exercise and supplying little energy through food intake, they are at risk for low energy availability (LEA). The hormonal and physiological effects of LEA are well known, but the effects of LEA on physical activity behavior outside of exercise and specifically on non-exercise activity thermogenesis (NEAT), i.e., non-exercise daily energy expenditure through, for example, everyday activities such as performing household chores or climbing stairs, have not been systematically studied.
For this reason, we performed a secondary analysis of recreationally trained young men: Participants completed two 4-day conditions of LEA (induced by restricted food intake), one with and one without endurance training. In addition, they completed two control conditions with balanced energy availability (sufficient food intake), again one with and one without endurance training. We found that exercise-independent energy expenditure (NEAT), was not impacted by low energy availability or by time spent in moderate-to-vigorous or low-intensity physical activity. However, when LEA was achieved with exercise and diet, compared with diet alone, less time was spent in low-intensity physical activity while all other categories of physical activity were maintained. This indicates that the trained adults did not compensate for additional exercise by being less active and instead maintained their activity.
Collectively, this suggests that LEA does not impact non-exercise activity thermogenesis per se, but the way in which it is attained may impact their physical activity behavior outside of exercise.
For more information, you will find the full-text here.