Can exercise beat your obesity genes?

Short answer

Yes. In active adults the obesity gene's effect was 27% smaller, and an analysis of 9,563 people found weight loss did not differ by gene. People at higher genetic risk needed to walk 2,280 more steps a day to match the risk of someone in the middle.

Can exercise beat your obesity genes?
'Obesity genes → born to gain fat → exercise is useless' — does this formula hold?
Some say that gaining fat easily is in your genes, so exercise is useless. We checked how strong the genes are, and whether exercise and diet weaken them.
Are the genes really that strong?
People at high genetic risk had more than 3 times the obesity
In a US study of 3,124 people who wore activity trackers for about 5.4 years, 13% of the bottom 25% by obesity gene score became obese, versus 43% of the top 25%. Over the same period, more steps meant lower obesity risk.
Does moving weaken the genes?
In active adults, the effect was 27% smaller
An analysis pooling 45 studies (218,166 people) found that each copy of the risk version of the best-known obesity gene (FTO) raised obesity risk 1.30 times in inactive people and 1.22 times in active people. In active adults the gene's effect was 27% smaller. This difference did not show up in children.
Does weight loss depend on the gene?
In 9,563 people, no difference in how much was lost
Re-analyzing 8 randomized trials (9,563 people), carriers of the FTO risk version lost the same amount of body weight, BMI and waist through diet, exercise or drugs — there was no difference. Splitting by method, length, sex or age did not change that.
What if you add up hundreds of genes?
Top and bottom 5% gene scores, no difference in loss
From 38,621 people in Finland, researchers picked 223 from the top 5% and bottom 5% of obesity gene scores for 6 months of diet coaching. The top group started with a BMI 3.0 higher, but how much coaching lowered it (1.51 on average) did not differ by gene score.
Diet plus strength training
145 people lost fat regardless of gene score
145 people in Japan did a lower-carb diet and strength training for 8~12 weeks. An obesity gene score built from 75 gene variants did not predict how much their BMI would drop. They lost fat regardless of gene score.
With high genetic risk, how much more walking?
2,280 more steps a day
In the 3,124-person study, people at the edge of the top 25% gene score needed 2,280 more steps a day on average (11,020 total) than those in the middle to have the same obesity risk. To match people at the edge of the bottom 25%, they needed 4,430 more steps a day at a BMI of 24.
Bottom line: genes set the starting line, exercise changes the result
The formula breaks at 'exercise is useless'
Higher genetic risk meant more obesity, but in active adults the gene's effect was 27% smaller. Weight lost through diet and exercise did not differ by gene. People at high genetic risk matched the risk of those in the middle by walking 2,280 more steps a day.