OVERVIEW
· How useful are classifications such as ‘overweight’ and ‘obese’ for us as individuals when it comes to predicting disease risk?
· When it comes to determining whether we run the risk of obesity-related diseases, it’s where fat is stored that really counts.
· We ask some big questions – is thin best, and is it possible to be ‘fat and healthy’? – and get some surprising answers.
In the last two chapters, we dealt with the usual suspects of diet and physical activity, and hopefully set the record straight on some important issues. True to the spirit of keeping the best till last, there’s another dimension to this debate that we’ve kept securely tucked up our sleeves until now.
Here’s the thing. We’ve got so wrapped up with aspiring to the ‘ideal’ body weight, that we’ve missed a trick. We’ve got hooked into thinking that it’s all about the numbers on the scales. If the numbers are good, we’re happy. And if they’re not, it spoils our whole day. The big snag with this sort of thinking is that we’ve got the ‘ideal body weight’ confused with the ‘ideal body’. When it comes to our weight, it’s really not all about the numbers on the scales. In fact, let’s question the unquestionable, and challenge the very idea that thinness necessarily goes hand-in-hand with health and beauty.
What does it mean to be fat?
Back in 1970, Scott and Law attempted to define the morbidly obese:
When an obese individual attains the gargantuan level of the fat man or fat woman in the circus, and maintains this degree of massive obesity for many years, we believe the adjective morbid should be added to emphasize the serious health implications and severe, life-shortening hazards of such grotesque accumulations of fat.
Forty years on, while the language we use to define excess weight has (thankfully!) progressed, we still find ourselves questioning how relevant these definitions are.
The most common measure used to define people as either underweight, a healthy weight, overweight or obese is Body Mass Index, or BMI. It’s a simple calculation worked out on the basis of your height and weight (you can calculate it by dividing your weight in kilos by your height in metres squared). A BMI of 18.5–25 is the standard ‘healthy’ weight range, whereas 25–30 is ‘overweight’ and above 30 is classified as ‘obese’. So, to show you how it works, a 60kg woman with a height of 1.65m, has a BMI of 22 [60÷(1.65)2], which is classed as ideal.
For working out averages in a population, BMI is a very helpful device because it’s quick, inexpensive and gives a general calculation. But when it comes to individual measurements, BMI lacks sensitivity and is a bit vague. To illustrate our point, you may have the same BMI as someone else, but you may also have twice the amount of body fat. Or, you may be a muscular rugby or gridiron player, but according to your BMI, you are classified as ‘obese’. You can see that when it comes to individuals, looking at a simple weight to height ratio can be pretty misleading.
Wladimar Klitschko, a world heavyweight boxing champion, is 1.98m tall and weighs in at 110kg when competing. His body mass is 28, which classes him as overweight! Indeed, over half the England rugby team would be classed as obese, based on their BMI. We don’t want to be the ones to tell them that they need to lose weight!
Not all fat is equal
There’s also another glitch. We know that having increased body fat is associated with a significantly increased risk of many diseases. But there’s an intriguing anomaly, as we will soon see. Numerous studies have found that this is not always the case. How could they go against the grain of one of the most established health principles of our times? Well, the thing is, it’s not the amount of fat per se, but the distribution of fat that confers risk of disease. It’s where we store fat that really counts, which explains why traditional measures, such as body weight and BMI, can be grossly misleading.
In 1947, Jean Vague coined the terms ‘android’ and ‘gynoid’ to define the two commonly observed body shape types – the ‘apple’ and ‘pear’ shapes respectively – suggesting that these different shapes conferred different health risks. Since then, it has become well established that it is abdominal obesity (android) that is associated with increased risk of cardiovascular disease, diabetes and cancer. For example, data from the large-scale EPIC study showed that abdominal fat was significantly associated with mortality risk, independent of BMI1.
So, along came a new measure for being not just overweight, but also at risk of disease – a straightforward measurement of waist circumference. Based on that, it’s now recommended that women and men keep their waist circumference below 80cm (32in) and 94cm (37in) respectively. The trouble is, it turns out that this is still a bit too simplistic and can be misleading. Not all fat is equal, and fat stored around the middle consists of two types of fat. There is the superficial and deep subcutaneous fat tissue (in effect, the ‘surface’ fat), and then we have the visceral fat tissue, the stuff that gets packed around our organs and spells trouble.
Here’s where things get interesting. We tend to think that fat, or adipose, tissue is just a place where we store excess energy – a bit like a big storage depot. It just sits there, inert and benign, not doing much at all thank you very much. We couldn’t be more wrong! Fat tissue is metabolically active. It manufactures and releases a host of hormones and pro-inflammatory chemicals that have been coined ‘adipokines’2. And it’s these chemical ‘nasties’ that are believed to confer the detrimental effects on our health of being overweight. Where do most of these adipokines come from? Visceral fat. This explains why it’s visceral fat that is linked to the greatest risk of breast cancer, hypertension, raised cholesterol, diabetes and inflammation3,4,5.
The Guinness World Record for the largest waist belongs to Walter Hudson of New York. In 1987, he measured in at 302cm (120in) – 30cm (12in) more than the record for the world’s tallest man. He died just four years later, aged 46.
The corset was a popular fashion choice in the nineteenth century, giving the appearance of a slim waist. Wearers often suffered shortness of breath, movement restriction, weakness, digestive problems, fractured ribs, uterine prolapse and displacement of the liver. Still, this didn’t deter them from their ideals of looking good no matter what, and many women wore a corset even during pregnancy.
The skinny fat
We all know one. And most of us are probably guilty of feeling more than just a twinge of jealousy towards them. It’s that person. You know, the one who can eat whatever they want, never exercise, yet never put on a single pound… ever. We want what they have, but what is it? Good genes? A fast metabolism? A gift from God? Whatever it is, we want it.
But what if we told you that person might not be so lucky after all? What if their indomitable body could be a ticking time bomb, with no warning until it’s too late? While it may not show on the outside, it’s possible that their organs may be engulfed in visceral fat, which is sending out a deluge of noxious chemicals. Welcome to the phenomenon of the skinny fat.
Professor Jimmy Bell specializes in molecular imaging at Imperial College London. Using MRI technology he performs 3D internal scans of the body, which show how body fat is distributed. He found that 14% of men and 12% of women who are of ‘healthy’ weight according to their BMI, have significant excesses of visceral fat6, putting them unwittingly at risk of all the obesity-related diseases. And who might we find among the ranks of the ‘skinny fat’? Professional models, no less7. And one of the greatest risks for having a high visceral fat level, regardless of BMI, was brought about by following fad diets to lose weight.
If you’ve got the cash, there is another way to the so-called ‘perfect body’, and that’s surgical removal of fat stores. The American Society of Plastic Surgeons reports that in 2010, 203,000 liposuction procedures were carried out, making it the fourth most popular cosmetic surgery in the USA. Liposuction, however, only removes fat from the subcutaneous layers. The dangerous visceral fat, with all the risks it entails, remains untouched. Undergo this procedure believing it’s the cure for obesity and its related health risks, and you’re in for a shock. In fact, it has even been suggested that in those with high visceral fat, it’s possible that subcutaneous fat may actually offer some protection8.
Fat distribution may have more than just physical effects. In an observational study of 16,325 females, those with the hourglass shape tested smarter and had smarter children. The authors suggest that such body fat redistribution contributes essential fats to neuro-development9.
Fat and fit?
The effects of exercise on reducing our visceral fat stores and improving our health are truly dramatic. In the last chapter, we described the health benefits of being active. And we know now that physical activity ameliorates the health hazards associated with obesity, regardless of a person’s overall weight or BMI10. In 2008, the results of an examination of 5,440 US adults were published11. They measured a range of risk factors for disease, including metabolic parameters such as blood pressure, triglycerides, glucose levels, inflammation levels and cholesterol profile, and uncovered some surprising results.
The prevailing assumption that being overweight or obese is automatically associated with bad health just didn’t ring true. Half of overweight people (BMI 25–30) and one third of obese people (BMI >30) had healthy metabolic profiles, with blood results that didn’t show them to be at increased risk of disease. And here’s the twist. For nearly one quarter of the ‘healthy weight’ individuals, their results showed metabolic abnormalities that suggested increased disease risk.
What on earth was going on? What factors could begin to explain this disparity? We’re sure you’ve guessed already: one of them was physical activity levels.
Let’s look at it another way, by checking out a study that examined individuals who had similar BMIs and waist circumferences12. To the naked eye, the slim would undoubtedly look similar, trim and healthy, and the overweight, all fat and unhealthy. Where they did differ though was in their levels of physical activity. All the overweight individuals had similar amounts of fat and the same waist size, regardless of whether they were fit or not. But here’s the important bit. After an MRI scan it was found that the overweight and unfit had nearly twice as much dangerous visceral fat as the overweight and fit. A similar trend was also found in the fit versus unfit slim individuals.
Fitness is the key
Fitness is a massive predictor of mortality. In a study of 21,925 men over eight years, those who were lean and unfit had twice the mortality rate of those who were lean and fit13. A 12-year study of adults aged over 60 suggested that the death rate of the unfit was more than three times that of those who were fit14. Fitness was measured by a treadmill endurance test, and all it took was to increase the time by about five minutes to cut mortality risk in half.
Considering the well-known health benefits of exercise, should we really be surprised that individuals who are fit are healthier than their unfit counterparts of the same weight? Perhaps more shocking is the repeated finding that individuals who are fit and overweight have lower rates of diseases and mortality than unfit ‘healthy weight’ individuals13,14,15,16. These results are especially apparent in the mild to moderately overweight category, where it appears perfectly possible that you can be ‘fat’ and healthy. So you see it all comes down to your visceral fat levels, which ultimately determine your true risk of chronic disease.
Let’s take the most extreme example: the Sumo wrestler. A typical Sumo wrestler would have little problem in meeting the criteria for ‘morbidly obese’. While we may think that their extraordinary bulk is incompatible with health, it appears that they are in fact metabolically healthy. Their physical activity levels mean that, despite their excessive calorie intake (a staggering 6,000–7,000kcals per day), their visceral fat levels remain normal. The problems arise when they retire and the ensuing lack of physical activity means bad health rapidly encroaches upon them.
A study of 5,000 UK women, average age 29, commissioned by New Woman magazine illustrated the extent to which image disfiguration has become engrained in ‘normal’ society, as 97% of respondents deemed that a UK size 12 (US 10) was ‘fat’, and 60% expressed desire for a UK size 2–4 (US 0) figure. One third had tried to maintain an extreme 500kcals per day diet in an effort to reduce their dress size.
Some people are just ‘naturally’ fit, but this doesn’t get you off the hook. You may perform well in a fitness test, but irrespective of this, your lack of physical activity means you still run all the risks of ill health12.
Back to exercise
We hope it is now clear that it’s not just about what the scales say, or where you are on a BMI chart, your waist measurement, or even how you look. It’s all a bit more complicated than that. But the good news is that the solution is a simple one. We need to get out and exercise. Being active will burn those visceral fat stores. Ignore that at your peril. Being inactive for just a few months dramatically increases visceral fat stores, and with that comes sizable increases in metabolic disease risk, such as deterioration of cholesterol profile and impaired insulin sensitivity17. The flipside is that engaging in just moderate exercise – 30 minutes or more, five times per week – prevents this accumulation.
Don’t be fooled into thinking that you have to pound the treadmill for hours on end, or perform the physical feats of an Olympiad to get these benefits. Regular, run-of-the-mill, moderate activity will do just fine. Any sport or physical activity you enjoy (enjoyment and exercise don’t have to be mutually exclusive!) is suitable. It’s about day-to-day things too, like taking the bike instead of the car. Or getting off the bus a stop earlier, or simply parking further away to increase the distance you have to walk. Take the stairs instead of the elevator. Go outside and do some gardening. Play with your kids in the park, or get out more with the dog. Performed regularly, and at a moderate intensity, anything that has you up and moving will start to burn the calories and reduce those visceral fat stores.
Above all, don’t fall into the trap of judging the success of physical activity purely in terms of numbers on the scales. It can be pretty demotivating if you’re putting in the effort but not seeing the end result. Even in the absence of weight loss, there’ll be improvements on the inside that you can’t easily observe on the outside, notably the all-important reduction in visceral fat.
While short-term dieting studies also show reductions in visceral fat, we now know the pitfalls that lurk there. Besides, in complete contrast to exercise, dieting will also reduce muscle tissue. When the weight goes back on, it gets stored preferentially as fat first, ultimately conspiring to make our visceral stores bigger than ever.
THE PARTING SHOT
It’s not our intention to give a carte blanche to obesity, or to suggest that people can eat as much or as badly as they like, as long as they exercise later. That would be pretty foolish and it’s not what we’re saying. It remains an inescapable fact of life that there are far more overweight people who are unhealthy, than slim people who are unhealthy, and the heavier a person becomes, the more apparent the health risks. The bottom line is that being overweight and being inactive are both bad for your health. Either way, the solution is the same. Increasing levels of physical activity will bring about improvements in both.
For exactly the same reason, we need to challenge the belief that ‘thin is best’. Looks can be deceiving, and when it comes to these issues, society seems to be moving backward. Some people in positions of influence may treat it with contempt, but the hourglass shape of subcutaneous body fat distribution is quintessential of the healthy female form, and surely superior to our aspirations for the contemporary skinny look, indifferent to how it is achieved. So bogged down have we become in ill-conceived perceptions that we’ve missed the forest for the trees.
Society needs to change, and the responsibility for that rests firmly on the shoulders of health authorities, health professionals, the media, the weight loss and fashion industries, and our culture itself. We doubt that will be happening anytime soon, so our message is a simple one: get active or pay the price.
SUMMARY AND RECOMMENDATIONS
· While both have their purpose, don’t be fooled into thinking that your body weight or your BMI tells you everything.
· Not all fat is equal – it’s the distribution of fat that dictates your risk of disease, notably the amount of ‘hidden’ visceral fat.
· Visceral fat is bad news because it releases a host of noxious inflammatory chemicals, which increase susceptibility to chronic diseases such as heart disease and cancer.
· Looks can be deceiving and it’s perfectly possible to be thin on the outside but fat on the inside.
· Based on the same principle, the opposite is true – if you’re fit, it’s possible to be fat and metabolically healthy.
· It all boils down to getting more physically active – do that and you’ll melt away that visceral fat and reap the health benefits.