THE FAT YOU CAN’T SEE BUT MUST CONTROL
Internal body fat is a potential killer. It’s the fat you can’t see and usually don’t even know you have, but if you are a man, it is likely to be the fat that brings on your heart attack.
Internal fat, also known as visceral fat, lies around the organs in the abdomen. It is different from subcutaneous fat, the fat just under the skin, which is easy to identify.
Even lean men who look as though they don’t have an ounce of fat on their bodies can be carrying substantial quantities of internal fat. Men with big bellies can be fairly certain they have fat around their organs. The bigger and tighter the belly, the bigger the chance of internal fat.
Internal fat is dangerous because the body mobilises it so quickly. Not only can it be released into the bloodstream twice as fast as subcutaneous fat, but it also takes a shorter route. Because of its location, it gets directly into what is known as the ‘portal circulation and runs through the liver to the heart.
When a man is stressed, his body responds by mobilising fat to power his muscles and give him energy in case he has to fight or flee. If the stress is coming from physical exercise, his body burns up the fat.
If, however, the stress is mental and he remains sedentary, the fat remains mobilised but unused. Typically, a man can get all
‘stressed up’ with nowhere to go and with no way of physically discharging the energy.
In such a case, the mobilised fat is left to accumulate in his arteries. It’s like mud in a hose. First there is a little mud in the pipe, but over the years it increases and eventually blocks off the hose so that water can’t get through. But the tap is still releasing water at the same rate. The pressure builds and ultimately blows the hose off the tap, which is what classically happens in a heart attack.
Internal fat is such a good predictor of heart disease that several centres around the world are now looking for accurate, affordable ways to measure it. Once the technology is available, it is expected that a measurement of visceral fat will be a better screening tool for heart disease and late-onset diabetes than cholesterol, high blood pressure and a range of other factors. At present, the only reliable ways of measuring this fat involve expensive imaging devices not widely available, such as MRI (magnetic resonance imaging) and DEXA (Dual X-ray Absorptiometry).
Men and women generally store fat differently. While women are traditionally pear shaped and put on weight around their lower body – particularly the buttocks and thighs-men are apple shaped and easily gain upper body fat around the girth. There is a close correlation between abdominal fat and visceral fat, and this may be one reason for the higher level of coronary disease in men.
There are several myths about big male bellies. The first main one is that it is a ‘beer belly’. This is a total misnomer because beer – in fact all alcohol – is metabolised and not stored as fat. But men tend to have fat with their drinks. So while the alcohol is used as energy, the fat is stored, and what these men have is a beer plus nuts belly or a beer plus chips belly.
The second big myth is that a big, tight belly feels so hard because it is really stretched muscle. It is not muscle at all; it’s probably hard because of all the internal fat putting pressure on it.
A bloke with a big belly has an 80 per cent chance of having visceral fat. But a lean bloke can also have visceral fat, as a result of his genetics. The question is whether visceral fat can be reduced through diet and exercise. A review of all the literature on the subject found that diet alone seemed to have much the same influence on visceral fat as diet plus exercise although both together might cause greater weight reduction. It also showed that changes in waist size can indicate changes in visceral fat. For example, a 1-cm loss in waist size could mean a 4 per cent loss in visceral fat.
This means that reducing a waist from 120 cm to 100 cm could potentially lead to an 80 per cent loss of visceral fat, which would have a huge impact on disease risk. In the absence of accurate available machine measurement, waist size is probably the best indicator of improvements in internal fat levels.
The effects of visceral fat are not yet well appreciated, even among many members of the medical profession, but that’s likely to change as more research starts coming through.
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