Why BMI and body weight don't define your health, according to science

The idea that body weight alone determines health is being questioned by experts. Adam Collins, a nutrition scientist at the University of Surrey, argues that rising average weight in populations stems from shifts in food environments and lifestyles—not individual shortcomings. His research, shared on The Conversation, explores sustainable weight management strategies beyond quick fixes like diet injections.

Collins highlights that the connection between body weight and overall health is far less straightforward than often assumed. Scientific evidence does not strongly support the belief that higher weight automatically means poor health. Many individuals with a BMI above the 'normal' range still maintain stable blood pressure, healthy blood sugar, and normal cholesterol levels.

BMI itself has long been criticised for its limitations. The measurement fails to distinguish between fat and muscle, ignores activity levels, and overlooks metabolic differences. Meanwhile, being underweight—particularly in older age—can increase vulnerability to illness and complications. Rather than strict diets, Collins emphasises three key factors for well-being: regular physical activity, balanced nutrition, and a respectful attitude toward one's own body. For those without medical reasons to lose weight, rejecting diet culture can be a reasoned and healthy choice. His work even suggests practical alternatives, such as using protein-rich foods like eggs to naturally regulate appetite instead of relying on weight-loss injections.

The focus on weight as the sole indicator of health is increasingly seen as outdated. Sustainable well-being depends more on lifestyle habits than rigid dieting. Experts now advocate for a broader approach—one that values movement, nutrition, and self-acceptance over arbitrary numbers on a scale.