High-Intensity Exercise Curbs Junk Food Cravings
People who exercise a lot will inevitably need to consume more calories. Despite the body's need for energy, a new study reported that people who do high-intensity exercises are less likely to crave junk foods. This study suggests that high-intensity training could be extremely effective in promoting weight loss.
"The key aim of our research was to examine the brain's responses to high and low calorie food following a period of acute exercise," explained Dr. Daniel Crabtree, who is from the University of Aberdeen's Rowett Institute of Nutrition and Health, reported by Medical Xpress. "Our focus was on a region of the brain called the insula - commonly referred to as the 'primary taste cortex'. Activation in this region is increased in the anticipation of foods, and when consuming foods that we perceive as being pleasant."
For this study, the research team composed of Aberdeen nutritionists examined the relationship between high-intensity exercises and appetite. The researchers recruited 15 healthy men who were instructed to run for one-hour at one speed. The researchers then used functional magnetic resonance imaging (fMRI) in order to record the participants' appetite responses in the brain. During the fMRIs, the researchers had showed the men pictures of healthy and unhealthy food options. During a second visit, the researchers had the participants rest before looking at the images.
The unhealthy, high-calorie food options included pizzas, burgers and doughnuts. The healthier options were apples, strawberries, grapes and carrots. The researchers found that when the men looked at the high-calorie foods, the brain response measured by the activity level of the insula was reduced. Activation in this region increased when the participants saw images of healthy foods.
"We also asked people to rate their hunger levels and took blood samples to analyze two hormones relating to appetite stimulation and suppression," Crabtree said. "After running the volunteer's feelings of hunger were suppressed, and the appetite hormone analysis showed us that levels of the appetite stimulating hormone were reduced whilst levels of the appetite suppressing hormone were increased."
The researchers reasoned that since the insula is tied to thirst, people might want the low-calorie options because they have higher water content. By eating these types of food, the people can satisfy their exercise-induced thirst. This study was one of the first ones to use brain imaging to examine this particular link between food cravings and exercise.
"Our study focused on brain activity in healthy, lean volunteers. Further studies, encompassing volunteers who are overweight or obese, and employing different workouts and intensities are required in order to formulate how this link between brain activity and exercise could be best used in the development of advice for healthy weight loss," Crabtree said.
The study was published in the American Journal of Clinical Nutrition.