In the earlier days of our species, when food was scarce, being overweight was rare. Now, however, health experts recognize obesity as an epidemic in the developed world, with no end in sight. Canada is no exception: our obesity rates have risen dramatically over the past 30 years. More than half of all Canadian adults – and more than a quarter of all Canadian children aged 2 to 17 – are now overweight.
This wouldn’t be a problem if it weren’t for the health problems associated with being overweight. Obesity causes or contributes to a wide range of disabilities and illnesses, including arthritis, infertility, diabetes, some cancers, high blood pressure, blindness, kidney failure, heart attack and stroke.
Not every overweight person is at the same risk level, however. Over the past decade, researchers have been taking a closer look at obesity. They have increasingly found that while all obesity is a health risk, some patterns of overweight deserve particular attention.
The importance of weight
One way to measure whether you are overweight for your height is to calculate your Body Mass Index (BMI). This is your weight in kilograms divided by your height in metres, squared. (If you don’t think in metric, multiply your weight in pounds by 703, then divide that by your height in inches, then divide by your height in inches again.) There are many BMI calculators online.
According to the World Health Organization, BMIs are categorized as follows:
- Under 18.5 is underweight
- 18.5 to 24.9 is a healthy weight
- 25 to 29.9 is considered overweight
- 30 or more is considered obese
The importance of waist
While all overweight is important, research has shown that fat around the waist indicates a higher than average risk of developing diabetes or having a heart attack or a stroke, regardless of your BMI. Waist fat is assessed either by directly measuring the size of your waist or by calculating your waist/hip ratio (divide your waist measurement at its smallest by your hip measurement at its widest).
How big is too big? It depends on your ethnicity, family history, body type and age, but in general, men should be concerned if they have either a waist measurement of 40 inches (102 cm) or more, or a waist/hip ratio of more than 0.90 (an apple-shaped body). Similarly, women should be concerned if they have a waist measurement of 35 inches (88 cm) or more, or a waist/hip ratio of more than 0.85.
Even a small increase in waist size can affect your health. One study found that people whose waist measurement was 10% bigger had a 48% increase in their risk of death over several years.
People of normal body weight may still be carrying more fat than is healthy, so it’s important to be aware that factors such as your weight, BMI and waist measurement, family history, food choices and lifestyle all play a role in your heart health.