A study published recently in the US journal Obesity Research & Clinical Practice found that it’s harder for adults today to maintain the same weight as the generation 20 to 30 years ago did - despite exercising and eating exactly the same amount.

The authors looked at the diet information of 36,400 Americans between 1971 and 2008, alongside physical activity data of 14,419 people between 1988 and 2006.

An interesting correlation between BMI emerged: A person in 2006 - eating the same amount of calories, taking in the same quantities of protein and fat, and exercising the same amount as a person of the same age did in 1988 - would have a BMI that was about 2.3 points higher.

“Our study results suggest that if you are 25, you’d have to eat even less and exercise more than those older, to prevent gaining weight,” Jennifer Kuk, a professor of kinesiology and health science at Toronto’s York University, said in a statement.

To sum it up, people today are about 10% heavier than people were in the 1980s, even if they follow the exact same diet and exercise plans.

“However, it also indicates there may be other specific changes contributing to the rise in obesity beyond just diet and exercise,” Prof Kuk added.

Some scientists speculate that changes to gut bacteria due to artificial sweeteners and hormones found in food nowadays, along with the prolific use of anti-depressants, could be contributing to increased weight gain.