Anne Eckersley didn't feel she was terribly overweight, but her blood tests told a different story. "About five years ago, I had a routine check that showed my liver function was poor," says the 63-year-old.
"My GP said with my readings, I should be an alcoholic or on medication. But I only drink occasionally and wasn't taking anything."
Anne's weight had started to creep up when she hit her 50s and, at 5 ft 4 in, she weighed 73 kilograms, giving her a BMI of 27.6. So her doctor thought her liver reading must be due to a build-up of fat around the liver.
Anne's cholesterol was also high at seven (above the healthy threshold of five) and her blood sugar levels were pre-diabetic.
Crucially, like many middle-aged women, Anne - a retired headteacher who is married with a grown-up son - had started to carry more weight around her middle over the years.
"I used to have quite a small waist, but as I hit middle age, I became apple-shaped. My waist went up to 36 inches.
"I knew that the worst place to hold weight is around your middle, and my doctor said within two years I would have diabetes."
Evidence shows a big tummy is particularly harmful to health, raising the risk of chronic diseases such as type 2 diabetes and heart disease.
Last week, a major study from the U.S. found that having a fat tummy was more deadly than being obese all over.
The analysis, published in the journal Annals of Internal Medicine, followed 15,000 people over 15 years and found that men who had belly fat but a normal BMI had twice the risk of an early death compared with men who had a BMI categorising them as overweight or obese, but who carried this weight on their legs, bottom and arms.
Other diseases have been linked to a big waist circumference. Last year, University College London reported women who go up a skirt size every ten years between their 20s and 60s are at 33 per cent greater risk of breast cancer.
Yet our middles are getting ever bigger. The average waist size among British men is 37.9 in and women 33.4 in (over the healthy threshold of 37 in for a man and 31.5 in for a woman).
Why is fat around the waist dangerous?
The most likely explanation is that when fat is carried there, it's easier for it to seep into nearby vital organs such as the liver and heart.
Fat is not a static tissue - it's biologically active and produces hormones and other substances that can profoundly affect our health.
Scientists believe that when it accumulates around internal organs - known as visceral fat - it releases inflammatory chemicals and disrupts vital processes such as metabolism, blood pressure and clotting.
All of us have some visceral fat, but research from Imperial College London suggests up to 40 per cent of the population is carrying excess amounts. An estimated one in five is in the early stages of non-alcoholic fatty liver disease - or fat within the liver.
Even slim people can have visceral fat. Typically this occurs among people who look slim, but don't exercise. If a person lacks muscle, it means their body is less able to take up sugar in useful ways, meaning it ends up stored as fat.
The good news is that visceral fat can be lost. In fact, studies show that when we take steps to lose weight, it's the first fat to go.
"If you've got belly fat and try to lose weight, that fat will disappear preferentially," says Naveed Sattar, professor of metabolic medicine at the University of Glasgow.
"The first to go is the fat in your liver, and then your waist does start to come down."
Dr Louise Thomas, who studies visceral fat at the University of Westminster, says it's not known why it goes first. It may be down to the fact it has a better blood supply than the fat in other parts of the body.
"It may be simply that when you need calories to burn, the energy store with a good blood supply is most easily reached, so that is used up first."
One of the best ways to shift this fat, according to studies by Dr Thomas and others, is to exercise.
In one study, a group of young women of healthy weight did three 20-minute sessions of aerobic exercise a week, but kept their diet the same. After six months, though there were no significant changes to their body weight, BMI or waist size, MRI scans showed visceral fat dropped by 25 per cent.
"The women's glucose was reduced, their cholesterol was reduced - all the kind of things we want to improve. But because they couldn't see a very big physical difference, they thought it was disappointing," says Dr Thomas. It would be tempting to think that sit-ups shift abdominal fat. But while they tone stomach muscles, they won't burn many calories and, therefore, won't shift fat.
For that, aerobic exercise, such as brisk walking, running or aerobics, is best.
A 2008 trial by the University of Virginia involving 27 middle-aged obese women found that those who did high-intensity workouts - jogging and walk-jogging - lost significantly more abdominal visceral fat than those who did low?intensity walking.
Other researchers are looking at whether particular foods may have an effect on visceral fat.
At Imperial College London, Gary Frost, a professor of nutrition and dietetics, has found that fermentable carbohydrates - fibre that is broken down in the gut - found in foods such as oats and bananas, may stop you gaining visceral fat.
Last year, he published a paper where overweight adults who took a supplement containing a fatty acid called propionate, which is released when the gut ferments these fibres, showed a reduction in central fat tissue, gained less weight and less visceral fat.
It's not clear why, but "you're probably making the fat tissue more insulin-sensitive," he says.
However, according to Dr Thomas, reducing portion sizes and spending more of your day standing rather than sitting helps.
"Just doing that will have a benefit on the amount of fat you store in your liver and organs, even if it doesn't immediately cause you to visibly get slimmer or lose weight."
Anne Eckersley's story shows how losing abdominal fat can transform your health.
At the start of this year, her cholesterol was so high she should have been on statins, but her GP couldn't prescribe them because of her poor liver function.
Under his guidance, she embarked on a low-carbohydrate, high-fat diet (carbs raise insulin levels, which can encourage fat storage). She has cut out pasta, rice and grains and only occasionally has a slice of wholegrain linseed bread.
"I have lovely stir-fries, fruit and clotted cream and so on. I think my husband's been quite impressed at how I've stuck to it," she says.
In eight months she has dropped from 11½ st to 59.6 kilograms, and her waistline has reduced from 36 in to 31 in. "My waist is the most noticeable thing," she says. "My trousers and skirts got looser and looser."
Anne's cholesterol has also dropped, from seven to 5.2, and her blood sugars are in the healthy range. Her blood levels of gamma glutamyltransferase - a measure of liver health - have dropped from 115 to 63 (the normal range is zero to 45).
She is thrilled that such big changes have been made so easily. Experts are keen to emphasise that dangerous abdominal fat can be lost with simple changes.
"Studies show the best route is to start by making just one or two changes to your diet - cutting out sugary drinks would be top of my list," says Professor Sattar, who also advises taking up a physical activity.
"Part of the problem with motivating people to make changes is that they can't see what's going on inside," says Dr Thomas.
"If they make a lifestyle change and don't feel immediately that they're getting thinner or lighter, they might not think it's working. But it is."
Very small amounts of visceral fat are normal. Studies suggest men of normal weight carry 2 kilograms and women 1.3 kilograms of visceral fat.
If they are obese, the average is 5.2 kilograms for men and 3.6 kilograms for women.
Men are more susceptible to the problem, as they tend to store fat around their tummies. Women generally store it on their hips and thighs. Having fat here is safer, because it cannot spread to the organs.
This explains why although women have a higher body fat percentage than men, they are less prone to heart disease and diabetes and generally live longer. Certain ethnicities - including people of South Asian origin - are more likely to carry excess weight around the middle, so these groups tend to develop diabetes at a lower overall weight than others.
"The number one thing that dictates where your fat goes is genetics," says Professor Naveed Sattar. "Smoking may also alter your fat distribution and cause you to put it on centrally."
After menopause, women store more fat around their waist - possibly because oestrogen changes the behaviour of proteins and enzymes that control fat storage, says Dr Louise Thomas.
"One of the reasons for women having much higher rates of heart disease after the menopause is thought to be the change in body fat distribution from pear to apple shape."
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- Daily Mail