Dr Jean-Pierre Després is director of Research of Cardiology at the Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie in Quebec City, Canada, and scientific director of the International Chair on Cardiometabolic Risk (ICCR) at Laval University. He spoke to EurActiv's Henriette Jacobsen ahead of the conference "Eat well, drink well, move ... A small step for you, a big step for Europe" in Brussels, to be held on 17 September.
I’d like you to explain what we should measure when it comes to obesity. I know that you don’t like the BMI [Body Mass Index] number. Why is it not good enough?
There appears to be a distinction made between the usefulness of the BMI to describe populations around the world… for that purpose the BMI is a pretty decent metric. The higher the BMI around the world, the greater is the prevalence of chronic diseases such as cardiovascular disease and diabetes. So it’s fine to describe populations. I always mention that in my lectures.
The problem is in the clinical practice. When you watch what is at risk in a given individual, that’s where we find the BMI’s limitation. The most spectacular example would be for example the level of body fat content in a rugby or ice hockey player versus a sedentary person. You might have two individuals, both with the same BMI at 31, and one is a very muscular, extremely active and healthy individual and the other one is very sedentary… You see that this is a spectacular example. We’re looking at extremes, but this shows you that again if you only rely on the BMI, you will miss that.
This has been my research for more than 25 years now and we know that for any given BMI level, there’s a remarkable individual variation in the way individuals are going to put on body fat. Some are going to do it centrally in the inner organs, in the abdominal cavity not underneath the skin. We now have plenty of evidence that if you have too much fat in the abdominal cavity, you probably have too much heart fat, probably too much liver fat and probably too much muscular fat; too much fat in the skeleton muscle itself, described as fat storage in lean tissue. This is a very powerful predictor of the risk of developing diabetes and cardiovascular disease.
Again, the message is not that we should throw away the BMI, but once you have measured the BMI, we need to go beyond that to identify those individuals who for a given BMI would have too much of this heart, liver and muscle fat. This picks up on remarkable, individual differences.
So if I was very physically active, but wanted to find out whether I was obese or not, would it be enough for me to measure my BMI and for example my waistline?
You answer perfectly the question. My point is that the BMI should not be thrown away. It’s the first step. Let’s say that you’re in a sort of normal overweight range or obese range but then once it’s established, let’s say that the given BMI and your waistline is what should be predicted from your BMI or is it excessive as opposed to your BMI value. So it’s really on top of the BMI value. It’s extremely useful. So that’s the first thing.
The second thing is that waist is playing an important role. When we reshape the lifestyle of individuals who have a higher risk because they are overweight or obese, very often if we improve the quality of their diet, and we transform them from sedentary individuals to physically active individuals, there is quite a bit of data now, a selective preferential mobilisation of this abdorminal fat. You might lose a little bit of weight, let’s say a few percent of your initial body weight. You can lose 20, 25, 50% of this bad fat, so you see again the magnitude of changes in weight or the magnitude of changes in BMI does not necessarily reflect the loss of this dangerous fat.
We even have situations now where some individuals have not lost a pound whatsoever, but minimised their waistline by 5-6 centimetres and reduced the bad fat by 25, 30, 40%. So again, this is great added value as a target of measuring weight on top of BMI.
I have given interviews on TV and radio shows and afterwards get calls from people telling me that they understand what has happened to them after they went from being sedentary to physically active and not lost a pound, but losing fast in the waistline which has dropped by 4-6 centimetres. Then they understand that they are on the right track. If you are only focusing on weight loss, you might get very disappointed.
If health professionals could add waist measures on top of the BMI, that would help them discriminate those who are at higher risk, but more importantly in terms of tracking whether or not lifestyle changes are producing some meaningful facts on health. It won’t be a rare phenomenon to see a drop in waistline without a substantial drop in body weight.
How would it be possible to have a waistline of a normal size and still be at risk of developing for example diabetes?
Of course there are some lean individuals who for whatever reason have higher risk of diabetes and cardiovascular diseases because of genetic dispositions, but this is very, very rare.
We have looked at the prevalence of metabolic abnormalities among individuals that would have a low BMI and a low waistline and it’s extremely low. The vast majority of individuals that have metabolic abnormalities are increasing their risk of cardiovascular disease and type-2 diabetes have an excess of abdominal fat and we have published that a long time ago now, but the purpose actually of one of the objectives of the meeting that we’ll have on September 17 is actually indeed to increase the awareness around the issue that again…
We don’t want to confuse politicians and the population. We don’t want to throw away the BMI, but we want to add the BMI and waistline discussion in terms of risk and in terms of identifying a more appropriate target for therapy. That would be one step forward.
How would measuring the waistline instead of the BMI or measuring both change the amount of people considered to be obese?
Well, why are we worried about obesity? If it is a cosmetic issue, an excess of body fat, we wouldn’t worry about that. It would just be body fat content. The reason why we worry about it is because it’s associated with abnormalities and chronic diseases. When again the fat is stored in the wrong place, it’s a risk factor for various forms of cancer, type-2 diabetes, the relationship is extremely strong, and cardiovascular disease, so we worry about it. It causes prejudice to health. When it doesn’t do that, it’s purely a cosmetic issue.
We have plenty of evidence, and this particularly relevant to women with large hips and thighs, that this fat actually is good for their health. They have a lower risk of getting diabetes when they have large hips. Plenty of evidence indicates that not only is the fat in hips, thighs and legs neutral to health, it’s also protective.
What do you do with that if you are this perfectly healthy woman with a BMI of let’s say 28-29, considered overweight, but in much better health than I am and at much lower risk of developing diabetes than I am? I think we need to educate the population. Not every overweight or obese person is at higher risk. On the other hand, we need to refine the tool to identify those individuals who are at much greater risk because we want to focus our preventive efforts, our health resources on that subgroup of individuals, the overweight and obese individuals who are at higher risk.
We have proposed very simple screening approaches that can be used by any health professional worldwide and this is indeed to add on top of the BMI.
First of all, if you have a BMI below 25, you have a low risk. There are some individuals who have too much fat in the wrong places, but that’s pretty rare, but in the range between 25-35, the overweight and obesity range which is a very significant subgroup, we’re talking more than one half of the population depending upon the country you’re in, there’s a lot of misclassification there. The word has even been coined metabolic-healthy obese individuals to describe those individuals that are overweight or obese but are not characterised by the expected metabolic abnormalities. So that’s really in that range from 25-35 that adding the measurement of the waist could make a big difference.
When I read women’s magazines I sometimes notice these articles about ‘dressing for your shape’ and then categorising different shapes such as ‘pear shape, ‘apple shape’ and so on. Should we always consider the ‘pear shape’ to be healthier, so that it’s more a matter of where the fat is located when comparing two people with the same weight?
That’s an excellent image. The ‘apple shape’ is definitely at much higher risk than ‘pear shape’. ‘Pear shape’, which is again more frequently found among women, is associated with much lower risk of diabetes and heart disease for any given BMI. ‘Apple shape’ is indeed… It’s central fat accumulation associated with too much ectopic fat. It’s clearly a powerful risk factor for type-2 diabetes, cardiovascular disease and some forms of cancer. This really shows you that, don’t get me wrong, BMI is not bad, but we really need if we want to capture that risk, we need something else. And that’s why the waist circumference is so important.
For women it’s normal to have a ‘pear shape’, but maybe it’s not so frequent for men. How does gender play a role in this health debate?
This addresses a couple of things. More than 20 years ago, we had reported with imaging measurements that women on average have 50% less visceral fat than men. So we men have on average twice the amount of visceral fat than women. Women are protected against visceral fat accumulation and ectopic fat accumulation before menopause. At menopause because of the change in the profile, women will catch up with men. It takes 10-15 years and that’s why women often complain that while they are not gaining weight, their pants are getting tighter.
Many years ago, we followed a group of women and their weight changes over seven years. Their weight didn’t change, but their waist circumference increased by four centimetres and this gave them a 30% increase of bad visceral fat without any change in body weight. If you were a physician following these women over time, you would have thought that everything is fine because their weight has remained stable over the seven years. Well, there visceral fat has increased by 30% which is not good. It’s predictive of deterioration in their health profile and it’s predicted in the change of their waist circumference.
For men, there are substantial differences when putting on this visceral fat. Some men put it on, so that they have a ‘soft belly’ because the fat is underneath the skin. This is less dangerous that the ‘hard belly’ where the man looks less pretty than a pregnant woman, but when you have a middle-aged man who looks five-months pregnant then this is a very dangerous form of obesity in men. This is pretty common, unfortunately.
While other obesity experts seem to be focused on weight, you seem to say that as long as an obese person loses the right fat, it doesn’t matter that much overall if they lose weight. How correct is this notion?
You are giving me an excellent academic lesson. You can ask an obesity expert about losing weight whereas my expertise is more in the area of prevention of diabetes and cardiovascular disease. If you ask me for the sake of improving health of the European population, my focus would have been behaviours.
Obesity for me is a marker of unhealthy behaviours, but the first thing you do is assessing risk. You assess risk for a given patient. BMI causes prejudice to the health of that person. So then you measure waist circumference. Then you check for the usual things such as diabetes and the clinical signs of cardiovascular disease. If you are then dealing with a higher risk person, of course this is because that person has too much fat stored in the wrong place. What you want this person to achieve is to lose that bad abdominal ectopic fat. How to do it would be by not focusing on weight.
In our lifestyle programmes here, we don’t focus on weight loss. We focus on improving the quality of the diet. We improve nutritional quality and we focus on physical activity because if you only focus on diet and you are dealing with a very sedentary person… Humans have not been designed to be sedentary. So it’s going to be a complete failure and disaster if you only focus on calorie reduction.
If you were my physician and you would put me on a diet, you would no longer be my friend. This is incompatible with human physiology. We have been designed to be active animals. This is why if we are being sedentary, the old, redundant system which we have in our brain to make sure that we are going to eat and giving us a survival advantage or else we would have died thousands of years ago.
We have a redundant system in our brain so when we find food, not only are we going to eat a little bit, but we will really eat a whole lot. That was our way to survive thousands of years ago so this is still present in us. If we don’t understand that if regular physical activity is not part of the equation, there’s no way you can succeed long-term in terms of losing weight.
That’s why again in a focus of improving cardiovascular health, the metabolic health in European countries, the first focus should be, let’s reduce the sedentary time, an increase the level of physical activity by a few hundred calories. Then you have a margin to eat smarter. Then over the long run, you will improve your cardiovascular health.
Maybe you won’t lose weight, but you can be sure of one thing. If you are physically active and you eat smarter, you are going to lose some of this bad ectopic fat. Some might even lose weight, but it would be a side effect. But they are going to lose this bad fat and substantially improve their health profile. There’s plenty of data now supporting this. You see, the focus should no longer be that weight loss is the sub-optimal outcome.
How are we going to get this message across in Europe?
Well, we are going to have a meeting on 17 September, first of all… In Canada, we have the same dilemma because of the economic challenges we are in right now. We have limited healthcare resources so our point is let’s have better, simpler tools to identify those who are at a higher risk so that we can invest or support what I call the preventive intervention strategies. Resources are very limited so instead of focusing on the whole spectrum of individuals that are overweight or obese…
If you think about it, 75% of the population in North America is overweight or obese and you are close to that in Europe. If you focus on those you have too much fat stored in the wrong places rather than starting with the 75%, you can narrow it down to, I don’t know, maybe 20-25% and then the challenge is ‘What can we afford?’ in Europe depending of the economies.
You can run some pilot studies that could mobilise Europe using simple screening tools, simple interventions and strategies, not focusing on the weight loss, but rather on improving behaviours with the tools that we have. I think this is a remarkable opportunity because all countries around the world - including obviously the European countries - are facing a huge economical challenge right now. If you look at the cost of a chronic disease, type-2 diabetes, cardiovascular disease…
The life expectancy of our population has increased quite a bit. It’s pretty good in many countries, for instance France or Italy, but this is not life expectancy being healthy. We keep our population alive through costly treatment and medical procedures, it’s extremely costly. For many at the end of life, their life quality diminishes. We could save a whole lot of money by intervening earlier if we were able to screen those individuals who have too much belly fat, those who are sedentary and pre-diabetes.
The ultimate question at the end of the day is ‘How much prevention can we invest in this high-risk group?’ I call this a window of opportunity because we are sure that five years down the road, one-third of them will have type-2 diabetes and if we wait another five years, another third will have developed type-2 diabetes. Just think about this huge economic impact.
This is why we will have that meeting on the 17th of September and emphasising this. Type-2 diabetes is entirely societal disease mostly related to the way we eat and our sedentary lifestyle. We are talking about 100 millions of individuals that have type-2 diabetes. This is extremely costly and at the end of their lives, the last decade of their lives, it’s extremely costly with reduced productivity.
I think we really need to mobilise Europe around simple pilot programmes where we could show the added value of what we can afford in terms of simple screening tools where we could evaluate their waist circumference, but also a few simple questions about nutrition and physical activity. We and others around the world have shown the added value of assessing these risks. We want to raise the issue that when we talk about obesity, we need to go beyond weight and weight loss.