Why do some people lose weight effortlessly while others struggle with every extra kilogram?
A new study suggests the answer lies in our genes. A team from the University of Essex in the UK found a combination of 14 so-called “slimness genes.” Participants who carried more of these genes lost about twice as much weight from the exercise program as those who didn’t.
What Did the Scientists Discover?
The researchers enrolled 38 British adults aged 20 to 40 in an eight-week study. Participants provided DNA samples and were instructed to run for half an hour three times a week, as reported by the Daily Mail.
The team asked participants to keep their usual diet and lifestyle and to avoid other forms of exercise. The scientists weighed participants regularly and found that, by the end of the study, people with more of the slimness genes had lost the most weight. Those participants lost about 5 kilograms, while runners without those genes lost an average of 2 kilograms.
The most significant gene the team identified was PPARGC1A, which encodes the protein PGC-1α, a regulator of metabolism. The researchers say this gene accounted for about two-thirds of the weight differences and was common among the biggest losers.
Dr. Henry Chang, the study’s lead author and a researcher in the School of Sport, Rehabilitation and Exercise, cautioned that lifestyle and diet still play a crucial role in weight loss.
“This research revealed genes linked to slimming, but these genes won’t do anything without exercise and lifestyle changes,” he said. Without those changes, the genes “won’t unlock their true potential.”
Chang also stressed that exercise offers benefits beyond weight loss—from improving mental health to strengthening the cardiovascular system. He recommends continuing to work out even if the scale doesn’t move much.
The study appeared in Research Quarterly for Exercise and Sport. It builds on Dr. Chang’s earlier work showing that running performance also relates to genetics.
“Given that obesity is becoming an increasingly serious societal issue, a better understanding of how genes and their alleles affect the body’s response to exercise will change how exercise programs are personalized and how effective they are,” Henry Chang said.
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About two decades ago, researchers at the University of Bristol identified a specific gene—the melanocortin 4 receptor (MC4R). MC4R encodes a protein that helps the brain sense how much fat the body has stored.
When MC4R doesn’t work properly, the brain can mistakenly think the body has fewer fat reserves than it actually does, which increases feelings of hunger.
Researchers found that roughly one in 340 people may carry a mutation in the MC4R gene. People with that mutation tend to weigh more from a young age.
The scientists reached those results by studying the MC4R gene in a random sample of 6,000 participants born in Bristol in 1990–1991.
