Obesity has emerged as the defining public health issue of our time.

Worldwide, over two billion people are overweight or obese. And things are likely to get worse. As noted in a 2015 report in the Lancet, “No country to date has reversed its obesity epidemic.” A 2014 study on the global prevalence of obesity came to a similarly grim conclusion, noting that “no national success stories have been reported in the past 33 years.”

Given these depressing facts, it is no surprise that the topic can be tremendously polarizing. Futility can fuel frustration. And the incredible complexity of the issue makes room for strong views about causes (genetics, lack of sleep, too much artificial light, not enough chewing noise) and solutions (“fat” taxes, advertisement bans, menu labels, school exercise programs). Layer on top of those tensions the divisive nature of the issues associated with body image, methodology disputes and ideology-fuelled positions on the role of government. It has become very difficult to talk about obesity without offending or, at least, irritating someone.

Below is my take on a few of the touchiest obesity topics (gleaned from my personal missteps and public confrontations) and my humble suggestion about how to move forward.

The word “obesity”: Believe it or not, even this term stirs debate. How, exactly, should it be used? Are people obese or do they have obesity? The former is a label, the latter a description of a condition. For those not closely involved with obesity policy, this may seem like absurd semantic navel-gazing. It’s not. The issues associated with weight bias are profound. Not only does it affect the well-being of people with obesity (yep, that is how I’ll try to use the term), it can have a significant and adverse impact on efforts to lose weight. How people are identified matters.

Verdict: While it may seem stylistically awkward, given the documented harms associated with weight bias and stigmatization, we should strive to frame the issue in a constructive manner. People have obesity.

Body mass index: Almost every media story, study or commentary about obesity includes a mention of body mass index (BMI). The goal of this height and weight measurement, which has been used for over a century, is to provide a rough estimate of the amount of body fat (which is, from a clinical perspective, what is most relevant). As such, it is often used to categorize individuals as having obesity. But a growing body of research questions its value as a way of predicting an individual’s health status. One study found, for example, that using BMI alone leads to an underestimation of the number of people with an unhealthy amount of body fat.

Verdict: At the population level, BMI remains a valuable research tool. For individuals, however, I think there is an emerging consensus that it isn’t that useful. It might be a good starting point for a discussion about weight, but healthy (and unhealthy) people come in a range of shapes and sizes.

Strategies for losing weight: There are are some weight-loss strategies whose mere mention triggers angry debates. Not long ago I tweeted about a study exploring how often people should weigh themselves. I got comments like “How about never!” and “A scale doesn’t measure health!” and “Your self-worth isn’t a number!” These sentiments, which can be found everywhere, flow from the idea that stepping on a scale will hurt self-esteem, increase body-image issues and cause people to focus on weight instead of health. Plus, it simply isn’t fun. In fact, there is evidence that for some, weighing yourself regularly can be a helpful weight-loss and maintenance strategy. And the evidence regarding the psychological downsides isn’t very compelling, at least for adults. So, at a minimum, we should be open to looking at what the evidence says.

The same kind of polarizing response often flares up when other weight-loss strategies are discussed, including exercise (weight-loss benefits likely minimal), breakfast (data surprisingly mixed) and the odd recommendation of eating in front of a mirror (um, I’m skeptical).

Verdict: I am actually a bit agnostic about the frequent-weighing strategy (some of the relevant studies fall prey to the correlation-versus-causation critique). But debates about interventions should, as much as possible, be evidence-informed. Let’s not use ideology or unproven assumptions to stifle constructive discussion.

The grim truth about sustained weight loss: Reviewing what the science says about weight-loss success can be a real downer. But, alas, the data are pretty consistent, depressingly so. Study after study has shown that very few can keep weight off over the long term. Yes, there are success stories, and any amount of weight loss likely has health benefits. Still, despite the billions and billions made by the weight-loss industry and the never-ending claims of new this-is-the-answer approaches, diets rarely work. Indeed, one group of scholars have gone so far as to suggest there is “little support for the notion that diets lead to lasting weight loss or health benefits.”

This reality is hardly inspirational. So it is no surprise that no one wants to hear about it. When I’ve made the point publicly, there is always a range of responses, including denial (“I know someone who lost weight!”), anger (“Why tell the public this bad news?”), bargaining (“These data might be relevant to other people, but not to me!”) and depression (“Oh, we are never going to solve this problem!”), but rarely, if ever, acceptance.

Verdict: We shouldn’t suppress the science as part of some sort of health promotion tactic. Developing a sustainable policy demands that we face the reality of our tough situation. However, in order to reflect what the science says about weight loss, we should, perhaps, stress weight maintenance, or more modest and long-term weight-loss goals.

More important, we should keep the emphasis on health and well-being. One thing we can all agree on is that a healthy lifestyle — eating well, exercising, not smoking — will result in health benefits, regardless of your BMI, height, weight, shape, bone structure, eye colour or percentage of body fat.

Timothy Caulfield
Timothy Caulfield est titulaire de la Chaire de recherche du Canada en droit et en politique de la santé, professeur à la faculté de droit et à l’école de santé publique, et directeur de recherche au Health Law Institute de l’Université de l’Alberta.

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