It's getting harder to lose weight regardless of exercise and diet, according to a new study published in the *Obesity Research & Clinical Practice*journal.
Research from the Faculty of Health at York University in Toronto, Canada found that an American adult in the 1980s had a lower BMI than a modern day American -- despite having the same diet and exercise habits.
The team behind the study examined the dietary and physical activity data of more than 36,000 Americans between 1971 and 2008 and then between 1988 and 2006.
Once the data had been grouped by activity, age, BMI and the amount of food eaten, they found that although a person in 2006 could eat the same number of calories, the same amounts of macronutrients and exercise the same as someone from back in 1988, they would have a BMI that was on average about 2.3 points higher.
The results show that people in the 2000s are around 10 percent heavier than they were back in the 1980s -- even though they're doing the exact same things to maintain their weight.
"Our study results suggest that if you are 40 years old now, you'd have to eat even less and exercise more than if you were a 40 year old in 1971, to prevent gaining weight," said professor Jennifer Kuk from the School of Kinesiology and Health Science at York University.
The study suggests that that factors like diet and physical activity form only a small part of the picture when it comes to why BMI levels are on the rise. "There may be other specific changes contributing to the rise in obesity beyond just diet and exercise," Kuk explained.
According to Kuk, factors such as medication use, environmental pollutants, genetics, timing of food intake, stress, gut bacteria and even nighttime light exposure could be causing weight gain.
This article was originally published by WIRED UK
