When Thin Is Fat

Wellsource.com

October 18, 2007

It turns out that what’s on the inside counts even more than we used to think. Recent research reveals that many people carry an unhealthy cushion of fat around their internal organs, which can lead to serious diseases later in life.

Jimmy Bell, a professor of molecular imaging with the Medical Research Council (MRC) at the Imperial College in London, and his team scanned more than 300 people with MRI machines to create "fat maps" showing where people store fat. People who are extremely thin but inactive may actually be "fatter" than heavier individuals who exercise. That's because people who are sedentary are more likely to have deposits of internal fat in areas not visible to the eye – such as around the heart, pancreas, and liver. 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.

The image at right (published in the MRC new release) shows an MRI scan of a slim male. The green coloring shows external fat, the yellow highlights fat deposited around internal organs. As you can see from this image, looking slim is not enough.

"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," says Bell in a MRC news release. "People have become obsessed with dieting, but doing this without exercise means they may be putting fat in the wrong places." Yo-yo dieting appears worse of all at forcing the body to lay down fat around vital organs.

Of the women scanned by Bell and his colleagues, as many as 45% of those with normal BMI scores (20 to 25) actually had excessive levels of internal fat. Among men, the percentage was nearly 60%.

Outwardly thin individuals who are inwardly borderline obese usually eat too many fatty, sugary foods and exercise too little to work them off. It would appear that nutritional alterations, such as eating more resistant starch, such as you would find in lentils and pulses, results in less fat being laid down in the abdomen. Bell is carrying out a trial on healthy volunteers to see what happens to their internal deposits of fat when they switch to a diet involving more grains and lentils.

Bottom Line: Here is a good reason to be physically active, even if you are within your normal weight guidelines.

Reference: Medical Research Council. Overweight? You might not know it [news release]. Dec. 11, 2006.

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