Physical activity can affect many aspects of metabolism but it is unclear to what extent this relies on manipulation of energy balance. Twenty-six active men (age 25 ± 7 years) were randomly-assigned either to consume 50 % more energy than normal by over-consuming their habitual diet for 7 days whilst simultaneously restricting their physical activity below 4000 steps·day-1 to induce an energy surplus (SUR group; n=14) or to the same regimen but with 45 min of daily treadmill running at 70 % of maximum oxygen uptake (SUR+EX group; n=12). Critically, the SUR+EX group received additional dietary energy intake to account for the energy expended during exercise; thus maintaining a matched energy surplus. At baseline and follow-up, fasted blood samples and abdominal subcutaneous adipose tissue biopsies were obtained and oral glucose tolerance tests conducted. Insulinaemic responses to a standard glucose load increased 2-fold from baseline to follow-up in the SUR group (Δ17 ± 16 nmol.120min.l-1; P=0.002) whereas there was no change in the SUR+EX group (Δ1 ±6 nmol.120min.l-1). Seven of 17 genes within adipose tissue were differentially-expressed in the SUR group; expression of SREBP1c, FAS and GLUT4 was significantly up-regulated and expression of PDK4, IRS2, HSL and VISFATIN was significantly down-regulated (P≤0.05). The pAMPK/AMPK protein ratio in adipose was significantly down-regulated in the SUR group (P=0.005). Vigorous-intensity exercise counteracted most of the effects from short-term overfeeding and under-activity at the whole-body level and in adipose tissue, even in the face of a standardised energy surplus.
Walhin, J. P., Richardson, J. D., Betts, J. A., & Thompson, D. (2013). Exercise counteracts the effects of short-term overfeeding and reduced physical activity independent of energy imbalance in healthy young men. Journal of Physiology, 591(24), 6231-6243. https://doi.org/10.1113/jphysiol.2013.262709