Why a 'normal' BMI can hide serious health risks like diabetes

A normal body mass index (BMI) does not always mean good health. Many people with a healthy weight still face risks linked to obesity, such as heart disease and diabetes. Experts now describe this as metabolically obese normal weight (MONW), moving away from the older term skinny fat.

BMI has long been used to assess health, but it misses key factors. It does not measure waist size, body fat levels, or where fat is stored—especially dangerous visceral fat around organs. Over the past five years, doctors have shifted focus to better indicators like waist circumference, visceral fat scans, blood sugar, cholesterol, and inflammation markers.

The term skinny fat describes those with a normal BMI but poor metabolic health. Poor diet, lack of exercise, and genetics can lead to high body fat, weak muscles, and hidden risks like high blood pressure or diabetes—even if weight stays the same. Lifestyle choices often play a bigger role than weight alone.

To reduce these risks, health experts recommend a balanced diet, such as the Mediterranean diet, and regular exercise. The goal is not weight loss but replacing fat with muscle. Guidelines suggest 150 minutes of moderate cardio weekly, plus strength training twice a week. Annual check-ups also help track hidden health issues before they worsen.

Relying only on BMI can overlook serious health problems. Better assessments now include body fat scans, blood tests, and lifestyle reviews. For long-term health, a mix of diet, exercise, and medical monitoring remains the most effective approach.