Researchers have shown through a new study that when we exercise on an empty stomach, our bodies tend to burn more fat and fuel favourable changes in your adipose tissue.
Scientists at University of Bath in Britain carried out a study on overweight males. Findings are published in the American Journal of Physiology – Endocrinology and Metabolism. Study participants were made to walk for 60 minutes at 60 per cent maximum oxygen consumption on an empty stomach and, on another occasion, two hours after consuming a high-calorie carbohydrate-rich breakfast.
During the study, reserachers took multiple blood samples after eating or fasting and after exercising. The researchers also collected fat tissue samples immediately before and one hour after walking.
Researchers were specifically looking for effects of eating versus fasting on gene expression in adipose (fat) tissue in response to exercise.
Corresponding author of the study Dylan Thompson explains that after eating, adipose tissue is busy responding to the meal and a bout of exercise at this time will not stimulate the same (beneficial) changes in adipose tissue. This effectively means that if we exercise in a fasted state, it might provoke more favourable changes in adipose tissue, and this could be beneficial for health in the long term
Scientists found from their analysis that gene expression in the adipose tissue differed significantly in the two trials. The expression of two genes, PDK4 and HSL, increased when the men fasted and exercised and decreased when they ate before exercising. The rise in PDK4 likely indicates that stored fat was used to fuel metabolism during exercise instead of carbohydrates from the recent meal.
HSL typically increases when adipose tissue uses stored energy to support increased activity, such as during exercise, Thompson said. These results reinforce the view that “adipose tissue often faces competing challenges,” Thompson wrote.
“This is the first study to show that feeding prior to acute exercise affects post-exercise adipose tissue gene expression,” the study said.
Their findings suggest that exercising on an empty stomach might provoke more favourable changes in adipose tissue, and this could be beneficial for health in the long term.