Overweight? You might not know it.

Overweight? You might not know it.

Medical Research Council, United Kingdom

11th December 2006

People who look slim and fit may not be as healthy as they appear. New research reveals that many people carry an unhealthy cushion of fat around their internal organs. As part of his research into type 2 diabetes, Professor Jimmy Bell of the MRC’s Clinical Sciences Centre at Hammersmith Hospital used magnetic resonance imaging (MRI) to scan more than 300 people to determine how and where the body stores fat.

MRI scan of a slim male, the green colouring shows external fat, the yellow highlights fat deposited around internal organs.

Professor Bell’s team discovered that potentially dangerous fat is often deposited around internal organs. The result is that the carriers appear healthy because they are slim.

The MRI scans suggest that up to 40% of the population could be carrying fat around and even in organs such as the liver, gut, heart and pancreas. Disused muscle may also be streaked with hidden fat that could provoke serious conditions like diabetes and heart disease in later life because the fat has a detrimental effect on chemical functions such as how energy is released from food.

Professor Jimmy Bell warns that looking good is not enough to stay healthy:

"The important message is people shouldn't be happy just because they look thin, it's not about looking fit or looking thin, it is about being healthy. You can look healthy but have a lot of fat internally which can have a detrimental effect. When you exercise you tend to burn the internal fat. Lifestyle changes have to include physical activity, it’s not enough simply to diet."

In fact, evidence suggests that yo-yo dieting could force the body to lay down fat around vital organs.

Professor Bell’s discovery challenges the assumption that a thin body is healthy by virtue of having little external fat. Instead he has shown that some underweight or slim people could actually be storing fat in a dangerous way.

Professor Bell continues:

“Traditional ways of measuring body fat such as Body Mass Index (BMI) give people the wrong idea of how much fat they have as it says nothing about internal storage. People have become obsessed with dieting but doing this without exercise means they may be putting fat in the wrong places.’’

“Through our research we are developing a full understanding of how genetic and environmental factors determine how much fat we deposit and where we put it. In the future we hope to use this information to change people’s lifestyles without going to the extremes of giving people drugs or operating on them.”