Our priorities are all out of shape. When we worry about fat, we focus on the stuff you can pinch between your fingers, the stuff that droops over waistbands and sabotages the silhouette.
But something far more sinister is going on beneath the slightly wobbly surface. When it comes to fat, what you see is not necessarily what you’ve got.
Get your fats right
Adipose tissue – plain old fat to you and me – comes in a variety of forms. The stuff just beneath your skin is called subcutaneous fat. It’s not particularly pretty but nor is it particularly harmful, so long as you don’t carry it in excess.
Visceral fat, however, is something else entirely. “This builds up deep in your abdomen from the top of the liver down. It surrounds your organs, so your liver, pancreas and kidneys are cushioned and floating in a mass of fat,” says Professor Jimmy Bell, a researcher at Imperial College in London who uses MRI technology to map fat in the body.
In recent years, scientists have confirmed that as far as your health is concerned it’s what’s on the inside that counts. The hidden fat, the tiny globules seeping into your organs and flowing through your bloodstream, is what increases a person’s risk of type II diabetes, heart attacks and other chronic health conditions. A recent study published in the journal Hypertension Research is one of many to have established a link between visceral abdominal fat and coronary heart disease.
The usual suspects are to blame – too much pastry and not enough panting. Genetics plays a role as always, but research has linked visceral fat with sedentary living and poor diets filled with empty carbs and hydrogenated fats. A new study in the Journal of Nutrition also found that high consumption of fructose, found most commonly in fizzy drinks, led to higher levels of the culprit.
“Weight has become too much of the story,” Bell says. “What everybody should really try to reduce is the fat in the wrong places. That’s the stuff within the organs and in the visceral area.”
And he really does mean everybody. Visceral fat is an equal opportunities sort of killer: it affects both sexes and you don’t have to be morbidly obese to carry it. In fact, researchers like Bell have come up with a classification for people who mistakenly think they’re lean and healthy just because they don’t store much subcutaneous fat beneath the skin. They’re known as TOFIs (thin outside, fat inside).
A man who looks trim but doesn’t exercise and regularly eats badly is likely to carry more visceral fat than is healthy. Compare that with a Japanese sumo wrestler who shovels thousands of calories into his body every day but stays active for his sport. The wrestler is more likely to store his fat near the surface and therefore enjoy better ‘metabolic health’ than the skinny ‘fat’ man who wrongly assumes that just because he can’t see it, it isn’t there.
Why is visceral fat so dangerous? “Fat is an organ,” says Alan White, professor of men’s health at Leeds Metropolitan University. “It’s metabolically active – it sends signals and toxic chemicals to the rest of the body that increase your risk of diabetes and heart disease.”
Scientists don’t fully understand all of the mechanisms but one thing we do know is that when you accumulate visceral fat it oozes into some of your internal organs, including the heart. It also gets into your liver, where the effects are particularly destructive. “It sends inflammatory signals around the body and also continues to produce glucose even when the body has enough,” says Bell. That increases your risk of type II diabetes. Other signals seem to go to the brain. “It makes people more lethargic and less likely to exercise. That, of course, causes even more problems so it becomes a vicious circle.”
From your liver, the fat also seeps into your blood in the form of cholesterol and triglycerides. These tiny parcels of fat slowly build up, gradually turning your bloodstream into a landfill for microscopic blubber. The process is called atherosclerosis.
As more and more fat is deposited on the walls of your arteries it forms a hard substance called plaque, which clogs up the system. Your heart must work harder to pump the blood through ever-narrowing corridors. In the worst cases, it causes blood clots and increases your risk of cardiovascular disease.
In evolutionary terms, the body was not designed for this. “The body was not created to have too many calories put in,” Bell says. “Evolution did not ‘predict’ this so it has no defence for it.” Which means one thing: it’s down to you to fix it.
Although visceral fat clings to your internal organs, its grip is not particularly strong. When you decide to take action – through diet, running or another form of exercise – your body first uses the fat stores that are most harmful to your health. Starting with the lipids in your blood, you then reduce the dangerous fat in your liver, followed by visceral fat in the abdomen, and then finally the subcutaneous stuff you can pinch between your fingers.
So which tactic is the most efficient at hunting down the hidden killer? “For me, there is no doubt that hypocaloric diets are the quickest way to remove this tissue,” says Professor Eric Ravussin, who studies obesity at the Pennington Biomedical Research Centre in the US. That means a dramatic cut in the amount of calories you take in – a scientifically backed crash diet if you will.
In one of Ravussin’s studies, obese patients lost an average of 12.6kg after 10-16 weeks on a hypocaloric diet. But as with any crash diet, this is best as a short-term measure for the clinically obese rather than a realistic choice for people who – let’s be honest – lack the willpower to stick to low-calorie diets long-term. And guess what happens when you quit? A study by Duke University in the US found that non-exercisers see an almost nine per cent gain in visceral fat in just six months.
“People who are able to include exercise in their lifestyle are more likely to be successful in the longer term,” Ravussin says. Still, you’ll need to go for more than a stroll. In the Duke study, people who exercised the equivalent of walking or jogging 11 miles per week didn’t gain any visceral fat. But those who jogged 17 miles a week successfully reduced both their visceral and subcutaneous fat.
This is why running is an effective weapon against toxic blubber; most of us can keep it up. The steady and sustainable weight loss you see when you lace up your running shoes ensures your internal organs are not surrounded and infiltrated by fat – even if sometimes you can’t see the difference.
One remarkable study involving runners showed exactly how this happens. In 2009, researchers from the University Hospital of Ulm in Germany followed entrants of the Trans Europe Footrace, a 4,500K odyssey from southern Italy to northern Norway – each carrying with them a mobile MRI unit. Every three or four days the runners, presumably grateful for a chance to put their feet up, underwent a full body scan that allowed scientists to track how their body composition changed as the race went on.
The results were impressive. Over the 64 days of the race, runners lost half their total body fat. Better still, the first thing to start disappearing was visceral fat, 70 per cent of which had gone by the end of the event.
When the research was published, Dr Uwe Schütz, who led the study, remarked, “Much of what we have learned can also be applied to the average runner. When you just begin running, the effects of fat reduction are more pronounced than in athletes who have been running their whole lives.”
High intensity training
So if your goal is to run off your visceral fat, how should you train? Research shows that to reduce fat tissue, especially in the abdomen, the most effective training technique is short bursts of high-intensity training. A study published in the journal Medicine & Science in Sports & Exercise compared the reduction of visceral fat in people training at different intensities.
Some participants continued with their regular exercise, some trained at or below their lactate threshold, others at high-intensity, each for five days a week. The training time was adjusted for each session so that all the participants burned off the same number of calories. Crucially, only those who trained at a high intensity saw significant reductions in their visceral fat.
High-intensity intervals may be quick and effective, but most researchers concede that they are the exercise equivalent of a crash diet. The eye-watering effort involved can put people off, especially if you’re a new runner or have been inactive through injury. “You run 400m at 90 per cent of your VO2 max and then walk the next 400m – for some people, I think it’s unrealistic,” says Ravussin.
The good news is there are other ways to reduce visceral fat. Resistance training, for example, has been linked with reduced visceral fat and increased endurance in runners. And even if you just get out there a few times a week, there is solid evidence that you are vanquishing the visceral fat and improving your health.
“We did a study on women who exercised three times a week for one hour,” says Jimmy Bell. “There was no change to their weight but did reduce their internal visceral fat and liver fat by up to 60 per cent. Personally, I don’t think it makes too much difference. Everything we do to increase physical activity will reduce visceral fat.”
The point is that no matter how far or how fast you can run, as long as you can maintain it, you will keep the hidden hazard at bay. In other words, if you move it, you lose it.
Do you have an excess of visceral fat?
If you answer yes to any of these questions, then you may well do:
- Are you inactive?
- Do you have a waistline bigger than 35in (women) or 40in (men)?
- Divide your waist by your hip measurement. Is it more than 0.9?
- Is the distance between your navel and lower back over 25cm?
Packed internally around your organs, harmful visceral fat is harder to spot, but body shape offers important clues as to what potential dangers lurk beneath the surface. If you match the ‘apple’ body shape, carrying more fat above the waist, it’s likely you’ll have more visceral fat than if you’re a ‘pear’, with more fat below the waist. The test is particularly relevant to women, as men are genetically predisposed towards an apple shape.
Weapons of choice
Choose the best kind of training for your fitness levels, then strike against visceral fat.
Best for: People with good baseline fitness levels.
Why: Research from the University of Virginia found it is the most effective exercise intensity for reducing visceral fat.
How: 400m @ 8-10 RPE*, then rest for 2 mins; repeat x 8, 3-5 times a week
Best for: People returning from injury or looking to start a maintainable fitness regime.
Why: Research from University College London found that exercising for 60 mins three times a week reduces visceral fat by 60 per cent.
How: Run 1 mile @ 4/10 RPE; run 2 miles @ 6-7/10; run 1 mile @ 4/10; run 2 miles @ 6-7/10; run 1 mile @ 4/10
*RPE = rate of perceived exertion: 8-10 represents almost maximal effort; 4 represents easy; 6-7 ‘comfortably hard’ that you could maintain for 20 minutes.
Visceral fat facts
5-10%: Lose this much of your total body weight and you’ll have made a real dent in your visceral fat.
33%: How much visceral fat you regain if you stop exercising one year after you first lose weight.
1 cup: How much green tea you should drink daily in order to boost the effect of exercise against visceral fat.
2.3 times: How much more likely it is that people who carry excess abdominal fat in their 40s will go on to have a form of dementia in their 70s.
30 mins: If you’re already not carrying much visceral fat, this is how long you should walk for, six days a week, to keep visceral fat at bay.
80 mins: This much aerobic or resistance training per week inhibits the regain of visceral fat for up to a year after a person first loses weight.