Exercise protects fat tissue from changes in inflammation levels and fat metabolism caused by a week of overeating, a new study finds. Previous studies indicate that as little as one week of overeating can impair glycemic control and insulin sensitivity. But while exercise has been shown to have a protective effect against metabolic impairments caused by eating too much, the specifics of how exercise affects the structure and function of fat tissue are not well understood.
In this pilot study, the researchers studied four lean and active adults who consumed 30 percent more calories than normal for one week. During the experiment, the subjects continued their regular exercise habits (at least 150 minutes of aerobic exercise and at least six days of exercise in the week). The research team measured glucose tolerance and abdominal fat samples before and after the week of overeating.
“Our preliminary findings suggest trends for increases in markers of inflammation (C-reactive protein, pJNK/JNK) after one week of overeating in people who do not exercise,” said Alison C. Ludzki, first author on the study. However, the team found that among the exercising subjects in this study, overeating did not increase the protein content of markers of adipose tissue inflammation (i.e., pJNK/JNK, pERK/ERK) or circulating C-reactive protein. The subjects also experienced no change in glucose tolerance or lipolysis (chemical breakdown of fat).
The study shows that short-term overeating combined with reduced physical activity induced a reduction in insulin sensitivity, hyperinsulinaemia and altered expression of several key genes within adipose tissue. The addition of daily vigorous-intensity exercise mostly prevented these changes independent of any net effect on energy imbalance. These results demonstrate that exercise has a profound effect on physiological function even in the face of a considerable energy surplus.
“Our preliminary findings expand on existing work to support a protective role of exercise in the metabolic response of adipose tissue to brief periods of overeating,” the researchers concluded.