Eating and Exercising: Genes vs. Thoughts About Genes

There’s ample evidence that your genetic makeup, the genes you inherit, can affect your tendency to gain weight (see my previous Psychology Today blog post, “Are you genetically predisposed to obesity?"). Perhaps you’ve inherited a tendency to find exercise difficult. Then it would be harder for you to be as active as your peers. Or, maybe you have a gene variant that lessens the feelings of fullness after eating so that you’re more inclined to overeat. If you have any of these genes are you doomed to a life of weight gain or increased difficulty with healthy eating and exercise?

A Stanford University study set out to understand the role of genes vs. peoples’ belief about how their genes influence their exercise and eating habits. It’s a little complicated but the results were striking!

Two hundred healthy men and women provided saliva samples for genotyping. They were divided into two groups focusing on either exercise or eating behaviors. The exercise group had their oxygen uptake measured while running for as long as possible on a treadmill. The eating group was given a liquid meal and asked to tell how full they felt while blood was drawn to test for hormones associated with feeling satiated.

In a later lab visit, the participants were given their genetic test results although some in each group were given false information. Some in the exercise group were falsely told that their genes made it more likely that they would have low endurance and that they would find exercise difficult.

In the diet group, some participants were falsely told that they carried a gene that made them feel that they need to eat more food to feel full. Later the participants repeated either the exercise or the meal trial. For both groups, participants who had been misinformed about their genetic predisposition exhibited both behavioral and physiological responses consistent with the false information they were given. (The accurate results were given in the debriefing at the end of the study).

The exercisers who were led to believe that their genes made it more likely that they’d have difficulty with exercise reported that they got tired more quickly than they had during the earlier trial. Also, their oxygen uptake and lung capacity had significantly diminished. There were similar results for the diet group. The false genetic feedback influenced both self-reports of satiety as well as the production of hormones affecting satiety.

In my previous blog post, I discussed a study demonstrating that healthy eating could alter the role that genes play in determining weight. The current Stanford study suggests that our beliefs about genetics affect both eating and exercise behaviors as well as the underlying physiological processes involved in eating and exercise. The findings of these studies suggest that changing thinking and healthy eating can reduce the effects of some of the genes that influence weight. So, what are your thoughts about your genes and weight?