Did you know that some body fat is
worse than others? When I was a trainee surgeon, the fat that was on
the inside, snuggled around the organs, was a glistening yellow, with a
healthy blood supply. But these internal fat deposits are now accused of being
health hazards. Like all sinister things, they go under various names –
visceral, intraperitoneal, active or belly fat. And we’re not talking
about “love handles” of subcutaneous fat beneath our skin. Visceral fat is linked to a higher risk of insulin
resistance and diabetes. These, in turn, increase the risk of
strokes, heart disease and some cancers.
The
solution
It is not completely understood how visceral fat
makes the body resistant to insulin (and hence allows blood glucose levels to
rise). One theory is that the liver and muscles become less
sensitive to insulin when there are higher circulating levels of
fatty acids, which occurs when you have a deposit of fat inside.
Fredrik Karpe, professor of
metabolic medicine at the Oxford Centre for Diabetes, Endocrinology and
Metabolism, explains: “The turnover of visceral fat is more dynamic;
if you don’t eat, then it reduces much more quickly than other fat depots.
But visceral fat does something nasty.” Hip and leg fat accumulates slowly
and is released slowly. But Karpe points out that, in terms of its evolutionary
role, visceral fat generates a massive supply of energy from fatty acids when
it is desperately needed. But, with our more sedentary lives and increased food
intake, it now leaks fatty acids, whether we need them for energy or not.
If we are apple- or pear-shaped may
depend on how our genes are expressed rather than any one gene defect. Karpe
warns that, as well as diabetes, belly fat can cause sleep disorders, as it’s
the equivalent of sleeping with a football inside your abdomen. This pushes
your lungs up and can disrupt sleep.
The good news is visceral fat is so
dynamic that you can shift it. You just have to eat less and exercise more –
about half an hour a day of quite vigorous exercise should do it. If you can’t
exercise without eating more, then just eat less: you need to have a negative
energy balance for your belly to melt away. This is obviously not easy. But
there is a handy way to see if you have a problem: measure your waist and then
your hips (around the largest point) and divide the waist by the hip. If the
resulting number is more than one for men or 0.85 for women, then you may have
too much. You are excused from sit-ups – all they will do is help your
abdominal muscles keep the fat in – but you should strive to shed it
in other ways. Karpe is very clear: “It’s unwanted and you can’t have too
little of it.”
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