When men exercise, they make healthier food choices, but the same can’t be said for women. According to new research, this phenomenon occurs because physical activity can alter men’s diet preferences.
How exercise changes your preferences
The new study, which came from the University of Missouri in Columbia, looked at male and female rats that were split into two mixed-gender groups. The “exercise group” had access to a running wheel and the “sedentary group” did not.
For one week, both groups ate a standard diet, but in the second week, the groups could choose between three diets: high-fat, high-sucrose or high-cornstarch. For four weeks, the rats had access to this choice of diets.
The results of the study
The male and female rats in the sedentary group mostly chose the high-fat diets for all four weeks. So did the female rats in the exercise group.
But the male rats in the exercise group reduced their intake of the high-fat diet and ate more of the diets that were high in sucrose and cornstarch.
“We expected to find differences between runners and sedentary rats,” says study co-author Jenna Lee, “but it was the sex differences that surprised us.”
Why the differences between males and females?
When the researchers looked at the fecal samples from the groups before and after the experiment, they noticed that the males and females in the exercise group had different gut microbiota, depending on their sex.
They also analyzed their brains and found that the female rats in the exercise group had higher levels of the reward-related opioid mRNA expression than the males. This might explain why the females had a higher threshold for reward than the males.
There’s also the possibility that running may help satisfy the male rats’ hunger, but not the females’, causing them to choose high-fat foods.
