Body Mass Index and its related Health risks

A way to assess Body Weight

BMI (body mass index) is the most frequently parameter used to provide a general assessment of body weight related to height, as well as to determine health risk. Simply defined, BMI is the result of dividing a person's weight (in kilograms) by the square of his or her height (in metres).

Depending on the result of such a formula (that can range from under 18.5 to over 30), a person can be classified in one of the following categories: underweight (BMI under 18.5), normal (BMI between 18.5 and 24.9), overweight (BMI between 25.0 and 29.5) and obese (BMI over 30.0). However it is important to stress that, when calculating BMI in children, a different scale is used.

BMI body measurements

BMI is a relatively reliable index used to assess overweight and obesity (as well as excessive thinness) in adult men and non-pregnant women. It has some limits, however. In fact BMI takes into account only the overall weight of an individual, without distinguishing between lean mass (muscle and bone) and fat mass. Thus, for example, athletes with much muscle mass may have a high BMI score but little body fat. Similarly, an older person who has lost muscle or bone mass, may have a low BMI, but a significant body fat percentage.

With the exception of some particular cases (athletes, pregnant women and elderly people), BMI supplies a reasonable estimate of adiposity and hence can be used to predict the risk of diseases related to obesity, such as type II diabetes, cardiovascular diseases (including coronary hearth disease and high blood pressure), stroke, metabolic syndrome, osteoarthritis, sleep apnoea, and certain cancers. 

High BMI, Obesity and weight loss*

 Doctors recommend that people who are overweight (BMI between 25.0 and 29.9) or obese (BMI over 30.0) should lose weight. Even a small weight loss (5 to 10 percent of current weight) can help overweight and obese patients stay healthy and lower their risk of developing obesity-related diseases. 

 Healthy weight-loss and maintenance involves long-term changes in eating and physical activity habits. A healthy weigh-loss diet should be low in sugar and fat, and should include a balance of complex carbohydrates that are rich in fiber (whole grains, fruit, vegetables), protein-rich foods (low-fat meat and diary products, as well as legumes) and essential fatty acids (nuts, fish and olive oil). Most physicians and dietitians recommend to eat small frequent meals throughout the day to avoid hunger and prevent overeating, as well as practice 30 minutes of moderate exercise (such as walking, bicycling or swimming) three to five times a week to increase energy expenditure.

BMI health risks and other important factors

It is important to remember that, when assessing the risk of developing obesity-related diseases, there are other factors (besides BMI) that have to be considered. These include waist circumference, which is an indicator of abdominal fat, as well as other conditions such as high blood pressure, high blood sugar, high triglycerides, high LDL-cholesterol, low HDL-cholesterol, physical inactivity and smoking. Although these conditions are not necessarily associated with overweight or obesity, they can actually increase the risk of developing obesity-related diseases.

 Therefore, when assessing health risk, it is necessary to take into account both BMI and waist circumference (which are reliable indicators of overweight or obesity), as well as all the additional risk factors listed above.

People with high BMI are advised to choose appropriate international health insurance.