So what matters more if you want to lose weight: exercising or eating less? The key could be exercise, researchers reckon; being a couch potato will put on the pounds more than eating.
Of course, it's better to eat less and exercise more, but the researchers have noticed that although there's been an obesity epidemic over the past 20 years, people haven't been eating more. Instead, their lives have become more sedentary, spending extra hours in front of the TV and less time being active.
Stanford University researchers have discovered a sharp decrease in physical exercise and an increase in average body mass index (BMI) in the US over the last 20 years, and yet caloric intake has remained steady over the period.
The ratio of American adult women who reported doing no exercise whatsoever jumped from 19.1 per cent in 1994 to 51.7 per cent by 2010; 43.5 per cent men reported doing no exercise by 2010, compared to 11.4 per cent in 1994.
It was the one significant difference between the two periods. Food intake was roughly the same, according to the data collected by the National health and Nutrition Examination Survey.
(Source: American Journal of Medicine, 2014; doi: 10.1016/j.amjmed.2014.02.026).