Are You Fat on the Inside?

Crash dieters may be storing high levels of internal fat around vital organs. It’s a health risk, but there’s a solution.

Looking slim makes you feel good but it doesn’t mean you’re healthy. Skinny women, particularly those who have yo-yo dieted and don’t exercise, may actually have unhealthy levels of fat on the inside.

Using magnetic resonance imaging (MRI) scans, doctors have found dangerous internal fat in slim people, wrapped around the heart, liver, kidney and pancreas, and streaked through underused muscles. Fit but overweight people with high body mass index (BMI) might actually have less dangerous internal fat than their skinny counterparts. These thin-obese or thin-on-the-outside-fat-on-the-inside (TOFIs) can’t see their fat – they usually don’t know they have any. And even their tiny kilojoule intake is testament to the fact that dieting alone won’t shift it.

Crash and Burn

All these people walking around thinking they’re thin and healthy might be wrong. 40% of women have high levels of internal fat. Excess internal fat can lead to coronary heart disease, high blood pressure, type 2 diabetes, and many cancers – including breast and colon cancer.

Stored for a Reason

A woman who crash diets is more at risk, because she can end up with more internal fat than someone whose weight doesn’t fluctuate. Only a small amount of fat is lost from internal stores when you diet. But when you put the fat back on, it’s deposited in the abdominal area first. Starving your body can also eat into muscle, and, once you put the fat back on, the body doesn’t replace that muscle but stores surplus kilojoules as fat – unless you exercise.

For women there are two particularly dangerous times for loading on the internal fat; when they yo-yo diet in their teens, 20’s and early 30’s, and post-menopause, when oestrogen levels drop and fat is deposited internally and abdominally. The biggest risk factor seems to be lack of exercise – an apple shaped body is more dangerous than a pear shaped one.

Other Causes

Other lifestyle factors play a part, particularly smoking and alcohol, which lay down fat in the abdominal region. That may be why, as many women have drunk more over the past 50 years, our average waist size has increased by 15cm, compared with an increase of 4cm around the hips and bust. The kind of fat we eat is important, too; two people of the same weight and height can have vastly different levels of visceral fat because one eats high fat processed foods, while the other eats healthier unsaturated fats. Long term stress also plays a part, triggering high levels of cortisol, a hormone that seems to promote fat storage in the abdominal region. All these factors show that almost anyone can be a TOFI. Even those with a healthy BMI can have large quantities of internal fat.

Good Fat

But fat is not all that bad. Fat produces chemicals, hormones and proteins, and affects every single aspect of the body and brain, two thirds which is made up of fat. This includes fertility, mood changes, our ability to think clearly and our immune response, which is why being too thin might actually make you less sharp, as well as unhappy and unhealthy.

Visceral fat is different from the dimpled, subcutaneous fat that lies beneath the skin, called cellulite. All fat is metabolically active, full of blood vessels and secreting hormones and proteins, which form part of the body’s metabolism.  But visceral fat is more active than external fat and more dangerous to your health, because of its position in the body. Internal fat seems to affect glucose levels – and that has major health implications, triggering type 2 diabetes and other chronic health problems.

The Big Shift

Thin or overweight, once you’ve got internal fat, is it possible to lose or shift it to a less dangerous site? Yes, with regular exercise. Thirty minutes of daily aerobic exercise is a good start, then build up gradually. The more active you can be each day, the better.

Experts say that combining a healthy diet with increased exercise is the best way to lose or keep off internal fat.