Diet Matters More Than Exercise When It Comes to Obesity

Eating habits play the leading role in the development of obesity – while physical activity remains important, it can barely offset the effects of poor nutrition.

Energy expenditure across lifestyles

An international study involving over 4,200 adults from 34 population groups found that total energy expenditure is almost identical despite vastly different lifestyles. People living in physically active societies don’t burn significantly more calories – nor do they have a noticeably different metabolism – than those in predominantly sedentary environments.

Diet is the main driver of obesity

The researchers concluded that reduced physical activity accounts for only about 10% of the rise in global obesity rates. The dominant factor? Diet – particularly the increased consumption of highly processed, calorie-dense foods. The impact of poor diet on weight gain is estimated to be ten times greater than that of inactivity.

Exercise alone is not enough

Previous studies have also shown that exercise programs alone rarely lead to significant weight loss. Instead, the body tends to compensate: the more we move, the more it conserves energy elsewhere – for example, by reducing the basal metabolic rate. Overall, total daily energy expenditure stays relatively constant. So while exercise remains crucial for weight management and overall health, it cannot undo the effects of an unhealthy diet.

What you eat matters most

A high intake of processed foods strongly correlates with increased body fat. Diets rich in carbohydrates can also contribute to fat storage, as the hormone insulin is required for processing carbs – and insulin also promotes fat storage while preventing fat breakdown. As early as 1965, Nobel laureates Berson and Yalow described insulin as the key regulatory hormone of fat metabolism. This suggests that the composition of the diet matters more than calorie count alone.