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The question: I've gained a little weight over the years, mostly around my waist. My wife affectionately tells me that I have a bowl full of jelly like Santa, but my BMI is normal. If my BMI is okay but I carry more weight around my waist, do I really need to worry?

The answer: Like you, when most of us reflect upon what a normal weight is, we usually use our body mass index (BMI) as a marker of health.

While our BMI is one of several measures we use for weight, on its own it is not the best indicator of health. It is calculated by taking your weight in kilograms and dividing that by height in meters squared. The challenge with using BMI as an absolute indicator of a healthy weight is that it does not differentiate between lean muscle mass and fat.

For this reason, healthy individuals who are high in lean muscle mass and low in body fat, will often have a high BMI and be categorized as unhealthy, while those with low muscle mass and high body fat will have a lower BMI and be incorrectly classified as healthy.

Despite its limitations, it is used widely for its simplicity and because it gives a quick estimation of weight targets for those who are overweight or underweight, and for people who are pursuing bariatric surgery and have to be above a specific BMI to qualify.

There is increasing evidence that how our fat is distributed in our body is a more accurate indicator of health risk than weight alone. You mention that your waist circumference has increased while your BMI is in the normal range. The truth is, the weight around your waist may indicate that you are actually at higher risk. It has been well established that fat that is stored around the waist correlates to visceral fat – or fat that surrounds our internal organs. This fat triggers inflammatory responses and the release of hormones in the body that can increase the risk of cardiovascular disease, diabetes, high blood pressure and high cholesterol.

A normal waist circumference in men should be less than 102 cm (40 inches) and less than 88 cm (35 inches) in women. If you are sitting above this number, regardless of what your BMI is showing, you are likely at higher risk for these diseases.

The good news is that you can work to modify this by making positive lifestyle changes in terms of your diet and activity. Reducing the fat around your waist is the best gift you can give yourself and your loved ones this holiday season.

Dr. Sheila Wijayasinghe is the medical director at the Immigrant Womens' Health Centre, works as a staff physician at St. Michael's Hospital in their Family Practice Unit and at Hassle Free Clinic, and established and runs an on-site clinic at Women's Habitat Shelter in Etobicoke.

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