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Obesity across the world
As a species, we are getting fatter. There are 400 million adults worldwide who are obese and one billion who are overweight. Children are getting fatter too. Worldwide, 17.6 million children under five are estimated to be overweight.

The latter half of the twentieth century saw major changes to all our diets and how we live.  We moved from plant-based diets to high-fat, energy-dense animal-based diets while at the same time becoming physically inactive. Many developing countries face the strange situation of having the problems of under nutrition and obesity, at the same time.

Obesity and cardiovascular disease
If you are overweight you may develop hypertension, diabetes and atherosclerosis.  These conditions will put you at high risk of cardiovascular disease.

You can tell if you are obese by the size of your waist, the ratio of your waist to your hips, and the relationship between your height and your weight.  This last measure is known as the Body Mass Index (BMI).  It is not a perfect way of checking your cardiovascular risk but as your BMI increases, so does your risk of heart disease and stroke.

 BMI is calculated by dividing your weight in kilograms by the square of your height in meters (kg/m2).

If your BMI is greater than 25 you are considered overweight. If you are of south Asian origin you may be considered overweight if your BMI is greater than 22.  If you are a woman, a BMI greater than 21 may adversely affect your heart’s health.  If your BMI is more than 30, you are obese and at serious risk of cardiovascular disease. If your BMI is below 18.5 your are probably underweight.

Your waist measurement can also tell you if you are at risk of developing cardiovascular disease.

Increased riskHigh risk
Men - not Asian94-101 cm>= 102 cm
Men - Asian->=  90 cm
Women - not Asian80-87 cm>=  88 cm
Women - Asian->=  80 cm

Why obesity causes cardiovascular disease
Previously, it was thought that fat was inert.  Now scientists understand that fat, especially intra-abdominal fat, has significant impact on our metabolism.

You have intra-abdominal fat if you have a big belly.  This fat affects your blood pressure; your blood lipid levels and interferes with your ability to use insulin effectively.  You use insulin to process glucose derived from food, our body's primary fuel. If you cannot use insulin properly you may develop diabetes, a risk factor of cardiovascular disease.

As you get fatter, your risk of developing Type 2 diabetes and hypertension rises steeply. Statistics show that 58% of diabetes and 21% of ischemic heart disease are attributable to a BMI above 21.