Trying to lose weight? Here’s why your genetics could be just as important as your exercise regime

Weight loss is a complicated process. There are so many factors involved including your diet, how much sleep you get each night and the kind of exercise you do. Our recent study shows that your specific genetic profile may also have a dominant effect on how well you lose weight through exercise. This might explain why two people who do an identical workout will see very different results.

We identified 14 genes that appeared to significantly contribute to how much weight a person lost through running. This suggests that some of us have a natural talent when it comes to burning fat and losing weight through exercise.

To conduct our study, we recruited 38 men and women born in the UK aged between 20 and 40. None of the participants regularly exercised at the start of the study. The group was randomly divided, with one half following a strict eight-week endurance programme that consisted of three weekly runs of 20-30 minutes.

The other group acted as a control. They were instructed to refrain from exercise and continue their daily routines as normal over this study period, including diet and lifestyle habits.

All participants conducted a running test to see how far they could run in 12 minutes, and were weighed before and after the study period. This was to gauge their initial fitness level and see how much they changed over the duration of the study. Body mass index (BMI) was also calculated.

Additionally, a saliva sample was collected from each person with a DNA test kit at the end of the study to assess their unique genetic profile.

It’s important to note that everyone who participated in the study had a similar body weight, BMI and aerobic fitness level at the start of the study. This is beneficial for multiple reasons. It meant everyone was at the same starting point, and some confounding variables were already controlled for such as fitness level. This ultimately improves accuracy in interpreting the results.

Exercise genes

Everyone in the exercise group managed to lose weight – around 2kg on average. The control group, on the other hand, put on a little bit of weight.

While a 2kg weight loss may not sound like a lot, it’s significant considering the exercise regime only lasted eight weeks and participants made no changes to their diet.

More significant, however, was the large variation in results among those that exercised – with an up to 10kg difference in weight loss between some of the participants. In fact, everyone within the exercise group improved at different rates.

Since we controlled for factors such as the intensity, duration and frequency of the exercises and used participants who’d had a similar body weight and fitness level at the start of the study, this suggests that some people naturally benefited more than others from endurance training.

When we looked at the genetic profiles of our participants, we found that differences in each person’s response to the exercise was strongly associated with their specific genetics.

We showed there was a strong linear correlation between the amount of weight participants lost and 14 genes that have previously been shown to be associated with body weight, metabolism or psychological conditions that affect BMI. The greater number of these genes a participant had, the more weight they lost. Our results also revealed that around 63% of the variance in weight lost among participants were explained by the genes identified.

For example, research has shown the PPARGC1A gene plays a role in metabolism and the use of fats for energy while exercising. Our study found that all participants who lost more than 1.5kg from exercise had this gene. Those who lost less than this did not have this gene.

Our findings align with what previous studies have shown. But while previous papers have only looked at the link between individual genes and weight loss, ours is the first to show that 14 different genes appear to work in combination to affect whether a person loses weight from endurance exercise.

Piece of the puzzle

Our study also suggests that while some people possess genes that make it easier for them to get fit and lose weight, people with these favourable genetics can only flourish if they actually exercise. In fact, our control group also had a number of these listed genes, but without exercise these genes could not activate, and so the participants did not lose any weight.

While our study provides compelling findings, it’s not without limitations. Since we only looked at endurance-based exercise, it will be important for future studies to investigate whether there are similar links between weight loss, genetics and combinations of different types of training (such as a mixture of endurance and strength sessions into a training plan).

It’s also worth mentioning that exercise is only one piece of the puzzle when it comes to weight loss. So even if you have all 14 of these genes, you won’t lose any weight or get fit if you don’t exercise and maintain a healthy diet and sleep pattern.

On the flip side, someone that only has a few of these favourable genes can still benefit if they exercise and are mindful of other aspects of their lifestyle.