Obesity and mortality revisited

By Eric Crampton 10/01/2013

The obese cost public health systems less in the long term because they die earlier.

And now it looks like those who are merely overweight rather than highly obese actually live longer than those who are of normal weight. JAMA reports that only categories 2 and 3 in the obesity rankings are associated with higher mortality risk; the overweight have a mortality risk of 0.94 compared with normal-weight individuals. From the study:

This study presents comprehensive estimates (derived from a systematic review) of the association of all-cause mortality in adults with current standard BMI categories used in the United States and internationally. Estimates of the relative mortality risks associated with normal weight, overweight, and obesity may help to inform decision making in the clinical setting.

The most recent data from the United States show that almost 40% of adult men and almost 30% of adult women fall into the overweight category with a BMI of 25 to less than 30.111 Comparable figures for Canada are 44% of men and 30% of women112 and for England are 42% of men and 32% of women.113

According to the results presented herein, overweight (defined as a BMI of 25-<30) is associated with significantly lower mortality overall relative to the normal weight category with an overall summary HR of 0.94. For overweight, 75% of HRs with measured weight and height and 67% of HRs with self-reported weight and height were below 1. These results are broadly consistent with 2 previous meta-analyses114– 115 that used standard categories. In a pooled analysis of 26 observational studies, McGee et al114 found summary relative risks of all-cause mortality for overweight of 0.97 (95% CI, 0.92-1.01) for men and 0.97 (95% CI, 0.93-0.99) for women relative to normal weight.

If the healthists keep talking about high proportions of the population who are overweight and obese, but it’s only the heaviest cohort within that group that experience increased mortality risk, and that group is only a small portion of the overall category we keep hearing about in the paper, why add the overweight and the category 1 obese to the tallies? To get bigger numbers and fuel perception of a crisis. Timandra Harkness explains [HT: @cjsnowdon]:

The reason this unassuming paper drew howls of outrage was the same as the reason the benefits of moderate alcohol intake are never noted without criticism: it spoils the headline health message that Fat is Bad.

Even worse, it blows the cover on the great myth – that an epidemic of Bad Fatness is sweeping the developed world. By including the dangerously obese, the innocuously tubby and the healthily plump in one category, ‘overweight including obese’, 60 per cent of the English population are labelled as potentially At Risk.

Being At Risk means these people need guidance and protection from their own vulnerable state, from the temptations of our obesogenic world and the frailties of their own sugar-addicted brains. At such a time of national peril, no measure is too extreme.

But less than a quarter of English adults are obese, according to new figures released just before Christmas, a fraction almost unchanged since 2007. And the ‘morbidly obese’ category – BMI over 40, the ones for whom it really might be worth shedding a few pounds, medically speaking – also remains steady since 2009 at 2.5 per cent of the UK population.

If only one in 40 of us is in significant weight-related danger, why do the other 97.5 per cent of us need to be protected by the state against sugary cereals and fizzy drinks? Could it be because only a few of us have fallen, but all of us are in peril? Weak, foolish and easily led astray, we need to be frightened back on to the right path. Thus Tam Fry, spokesman for the National Obesity Forum – who has called for children to be monitored from birth for signs of obesity – told the Independent: ‘If people read this and decide they are not going to die… they may find themselves lifelong dependents on medical treatment for problems affecting the heart, liver, kidney and pancreas – to name only a few.’

I suppose that an alternative hypothesis would be that some folks find the obese to be aesthetically displeasing and prefer to base policy interventions on a purportedly paternalistic basis than on an externality-via-aesthetics argument. The latter is more economically defensible, provided that we expect Hollywood et al get things roughly right about what sorts of actors more people prefer looking at, but harder to defend in popular forum. I’d also expect that since the morbidly obese suffer wage and health penalties already, any incremental Pigovean aesthetic tax added to the mix wouldn’t substantially affect things.

0 Responses to “Obesity and mortality revisited”

  • Healthists?

    “To get bigger numbers and fuel perception of a crisis”.

    Nope, to avert a crisis. You don’t have to have 100% of the population affected before you do something with preventable problems. Obesity used to be very rare, but isn’t now and is continuing to increase e.g. obesity in UK was 6% males/8% females 1980 now it’s risen to 22% males/24% females 2008/09. We know with increasing rates there are increasing amounts of people with obesity related diseases, and this research you’ve given shows high health costs and early death (which means that the person can no longer contribute to society and has a poorer quality of life, unlike a person of normal weight). I’ll note here, it was all cause mortality that was looked at, would have been very interesting to see if they’d teased out the mortality stats of the specific diseases known to be related to obesity.

    If the obesity rate has stayed static of late, great. Maybe the message is getting through and people are more aware of the health risks and trying to do something more than gradually gain more weight.

    This is all preventable, just as many cases of lung cancer are preventable by stopping smoking. It’s not stupid or irrational for health authorities to say we need to address the issue, it is irrational to try and argue that it’s just an itty bitty problem. If it’s one in forty, that multiplied by millions of population (to use the UK the 2011 figure was 63,181,775) this does affect a significant amount of individuals, all of whom will need medical care and will have their lives adversely affected in other ways.

    It’s not aesthetics, you have to separate out the potential health effects from societies attitudes. Official messages point to the risks of obesity and try and promote positive messages to exercise, they don’t say anything about individuals or their beauty. Culturally, there is a stigma but that shouldn’t mean we ignore the issue and hide it. Instead, we should attempt to deal with both and say that shaming or otherwise diminishing people because of their size is simply wrong as well as addressing health issues relating to obesity.

    “Why do the other 97.5 per cent of us need to be protected by the state against sugary cereals and fizzy drinks?

    The state isn’t doing that, there are no bans on breakfast cereal or fizzy. They aren’t protecting anyone from squat, words saying a particular junk food taken in excess don’t do a thing, The education is not that strawman, but directed at healthy eating and exercise, with limits on the junk food instead of stopping people eating what they want. This sort of rhetoric doesn’t help, you need to address the public health message and why it is being said. Maybe it would be more productive to have a discussion about denial, and why people don’t want to hear that some things aren’t good.

    That’s what the quote from Tam Fry seems to say, it’s very true that unfortunately there will be at least some people will take half the message (mortality OK for overweight) and use it to ignore that very excessive weight is definitely an issue. That they don’t need to worry this at all, they’ll be fine, won’t become ill.

    • Bloomberg has banned large sodas. There are persistent calls for sugar/fat taxes. The UK Labour Party has proposed capping the maximum amount of sugar in breakfast cereals. And all of it gets pushed with the idea that obesity costs the taxpayer money (except for that the obese die early and wind up costing less on a life-cycle analysis).

    • Just noticed that I hadn’t answered your opening question.

      In economics, we allow a pluralistic conception of the good. Whatever an individual values is allowed in his or her utility function. Maybe there are market failures around how much people consume of different things because of information or externality problems, but their basic utility functions we take as sacrosanct: it is not our place to judge the pleasures that others enjoy so long as they are not harming others in the process. We take them as primitives – things that come prior to the analysis and ought not be subject to critique. At least in the standard base models. Economists then get really tetchy when people try to claim that economists only care about money or wealth maximisation – money and wealth are one good thing, but if somebody chooses to consume more leisure and earn less, that’s up to him or her. Wealth is a good thing, other things are good things, and we trust individuals to weigh up the tradeoffs across all the things they think are good things.

      A whole lot of public health advocacy seems to take the line that the most important thing in the world is health and that it is always wrong when individuals make to trade off a bit of health or a bit of longevity for a bit of fun and enjoyment now. I call this “healthism”: the doctrine that it is always wrong to trade things off against health, and that policy should set health maximization as the most important goal. If health is the only or most important goal, then it doesn’t matter if a ban on large sodas inconveniences people, if regulations on salt content make food taste bad, or if fat taxes make people worse off on margins other than health. It’s the “If it adds one quality-adjusted life year, it’s worth it” mentality. For economists, QALYs are good. But so are other things – we accept tradeoffs and are not inclined to judge as worthy of policy intervention people’s choices to maximise a utility function that consists of things other than just health.

  • Of course, weight is only one of the issues around a poor diet. Those who have a nutitionally poor diet yet still remain an “ideal” weight are still are likely to suffer from poor health.

    A stronger focus on good eating habits, exercise and sleeping well seems more productive to me that obsessing over weight ( though of course, too much extra weight should be ignored either)

    • Agree to a point, but I’m not sure why the state has a role here. There’s reasonable argument that the American USDA food pyramid has done harm in pushing people too far towards carbs and away from fats, or at least if you listen to the Atkins/Paleo people. It seems the kind of thing that family doctors could talk with their patients about, or that public health nurses/midwives could talk with patients about. Maybe there’s a case for government provision of nutritional information pamphlets and the like. But going beyond that to regulations and taxes to encourage particular eating habits requires, to my mind, requires arguments based on the government saying something like “We know better than you do what’s good for you, and we’re going to treat you like children, and those of you who don’t need to be treated like children can suck it up and put up with it for the sake of those who we’re going to try to force to eat healthier foods.”