Overweight and obesity are measured using the Body Mass Index (BMI). BMI is defined as the body mass divided by the square of the body height, and is based on self-reported details of height and weight. The measurement does not distinguish between fat and muscle mass. Statistics Norway publishes groups with values recommended by WHO-EURO: somewhat overweight (BMI = 25-26.9), overweight (BMI = 27-29.9), obese (BMI = 30 or greater).