The choices we make in diet and exercise go a long way towards determining our body's mass, yet its our genes that lay the groundwork for gaining and burning fat reserves.
Scientists have recently discovered 14 'skinny' genes that could influence how individuals lost weight in response to exercise.
Researchers from the University of Essex and Anglia Ruskin University in the UK enlisted the help of 38 volunteers aged between 23 and 40 divided between a control group and an exercise group, who did three 20 to 30 minute runs per week over the course of a couple of months.
"We hypothesized that eight weeks of endurance training could reduce body mass, but participants would improve at different rates, and that this could be explained, in part, by their genetic differences," write the researchers in their published paper.
As expected, those who undertook the running routine lost weight. Yet the amount of loss varied significantly in ways that couldn't be attributed to differences in training alone. Through DNA testing, the researchers looked for gene variants that were more common in those that shed a greater amount of weight.
The team was able to identify variants in 14 particular genes related to greater weight loss: participants with most of these variants lost 5 kilograms (11 pounds) on average, compared with an average of 2 kilograms (4.4 pounds) for those with fewer or none of these markers in their DNA.
One gene highlighted by the researchers was PPARGC1A, which is responsible for the PGC-1-a protein. Present in the volunteers who lost the most weight, it's known to be associated with the way our cells process and manage energy. Analysis found the combination of the gene variants with training predicted 62 percent of the variance in lost weight in the exercise group.
Along with previous studies that have linked genetic factors to weight loss, the new research emphasizes how the goal of staying at a healthy weight is a process that's different for everyone, and may need bespoke approaches.
"The findings in this study confirm the relevance and potential application of genetics within exercise and weight management," write the researchers.
"As observed, the human genome plays a crucial role and has many interactions with exercise-based responses and adaptations."
That doesn't mean there's any weight loss magic in our genes. Effort and action is required in combination with genetics to manage weight, the researchers are keen to point out.
But it does show that our genetics can influence how effective exercise is, potentially contributing to the development of personalized weight loss programs.
What's more, exercise typically benefits our health in a multitude of ways. Interestingly, five of the 'skinny genes' identified in this study play a role in intelligence and/or mental health, including depression. There is a relationship between depression and obesity, with studies hinting at shared biological causes. Although this association is complex, research shows a strong genetic influence.
"This study highlighted some important genes associated with taking inches off the jeans, but it's important to remember that the genes will do nothing without exercise and lifestyle changes as they are all interlinked," says exercise scientist Henry Chung, from the University of Essex.
"Without intervention, they won't show their true potential and then it doesn't matter what genes you have."
The research has been published in the Research Quarterly for Exercise and Sport.
