For all the people in their 20s struggling to lose weight even though they exercise and try to eat right, it might be comforting to know that all that extra jiggle isn’t totally their fault — it could be the time they were born into. A recent study by the researchers at the Faculty of Health at York University in Toronto revealed there could be other factors unrelated to diet and activity causing people to have more trouble losing weight than they did in the 1980’s, according to a statement on the school’s website.

The research found that if you are 25 you have to eat less and exercise more than people did in the 1970’s and 1980’s to lose weight. Researchers looked at calorie and carbohydrate intake of about 36,377 people from 1971 to 2008 and the exercise frequency of from 14,419 people between 1988 and 2006, according to the report.

“We observe that for a given amount of self-reported food intake, people will be about 10 percent heavier in 2008 than in 1971, and about five percent heavier for a given amount of physical activity level in 1988 than 2006,” Ruth Brown, lead researcher and York University graduate student, said in a statement online. “These secular changes may in part explain why we have seen the dramatic rise in obesity.”

If diet and activity aren’t the keys to people having higher BMI’s than they did years ago, factors people can’t totally control could be the answer. Jennifer Kuk, a York University professor of kinesiology and health science, told the Atlantic that while the specific reasons still need to be researched, one reason could be the increased exposure to chemicals such as pesticides and food packaging substances.



Other reasons could include the increased use of prescription drugs among Americans, some of which could cause weight gain, and the makeup of microbiomes — collections of microbes that colonize the human body — which has changed in ways that could lead to weight gain. This could be caused from changes in meat, which has more hormones and antibiotics in it than meat 20 years ago.

Many studies have shown that eating less and exercising more will help people reduce weight. A University of Pennsylvania study found that sleep deprivation can also lead to weight gain, while other studies have found that exercise alone may not help someone lose weight, as some tend to eat more as a result of physical activity.