What goes down, must come up: yo-yo dieting and your health

Content note: talk of dieting, yo-yo dieting, fat shaming, and use of the medicalised terms ‘overweight’ and ‘obesity’ throughout.

I think blog-worthy material is like buses. You wait absolutely ages and then three come along at once. All of a sudden today there are so many things that have happened that I want to write about, I don’t know where to start. So I’ll go with the one that is currently open on my browser.

Because of my research, I unfortunately have to read emails from the consistently offensive ‘The Obesity Society’ (Brits will appreciate the highly appropriate acronym for a group of TOSsers). TOS claims to be “the leading scientific society dedicated to the study of obesity. Since 1982, The Obesity Society has been committed to encouraging research on the causes and treatment of obesity, and to keeping the medical community and public informed of new advances.” Given that there have been no advances in the “treatment of obesity” since 1982, what they mostly do is act as purveyors of moral panic, and do their best to keep the weight-loss and bariatric industries well funded.

Interesting aside: to get a brief synopsis of what TOS claim to be about, I searched for ‘tos.org‘. Turns out this is actually the address of The Oceanography Society, whose site I can most highly recommend for really cool content, images and links. I wouldn’t bother visiting the other one, which has the charming URL of obesity dot org.

But back to the point.

In a recent TOS newsletter, they linked to a piece about yo-yo dieting. The title, ‘Confessions of a yo-yo dieter’ sets the tone – lots of self-blame, lots of fast-binge cycling, lots of trying to lose weight ‘the wrong way’, and it continues like this with a quote from a Dr Adam Tsai, chair of the Public Affairs Committee of TOS, who first agrees it’s all about crappy behaviours, and then points out that the body homeostatically defends its weight and overcompensates on the side of preventing future starvation. (For a very thorough scientific explanation of how the body resists weight loss, check out this article, but note, discusses ‘obesity’ as a ‘disease’ and frames in terms of limiting weight loss.) He then goes back to recommending personal behaviour change, but at a more moderate pace. Because we have just so much evidence to suggest that this makes a difference. Not.

But the sugar-free icing on the low-fat cake is this little gem:

Even Dr. Tsai admits that it can be a bit depressing to know your body is fighting your diet. The good news is that constantly losing the same weight isn’t technically bad for your health. “It’s better to be able to lose the weight, and always better to spend time at a lower weight,” Dr. Tsai says.

I’m not even going to get into what “technically bad for your health” might mean, but the direct quote from Dr Tsai is illustrative of either a disturbing level of ignorance about a key outcome of his area of speciality, or that he is wilfully and deliberately promoting a course of action where the most likely eventuality is to worsen his patients’ health. Neither would surprise me.

First, the vast majority of weight loss attempts result in weight regain within two years, with approximately two-thirds experiencing rebound weight gain beyond their original starting point – see Dr Tsai’s own comments about how we have evolved to resist apparent starvation.

I think this parallels the public health messages around giving up smoking, where the single greatest predictor of a successful quit attempt is the number of previous quit attempts. In other words, keep trying. We also know that every day you don’t smoke is a day you are not inhaling carcinogens and other toxins into your lungs. In contrast, the more times you have dieted, the more likely you are to stay thin to end up bigger than before with a more disordered relationship to food and your body. And every day you spend at a weight below your natural setting point (which is probably higher than it would have been if you hadn’t been on all those diets), is a day that your body thinks it’s starving and ramps up the neuroendocrine assault needed to get you eating again, with a bit added on for safety’s sake.

But even worse is the claim that weight cycling in and of itself is not harmful. It is astonishing how often we hear, ‘oh well, too bad you didn’t keep the weight off, but you can always try again’, as if multiple weight loss attempts were a benign process. While there is some variability in small-scale studies, larger studies almost always show that weight cycling increases risk of morbidity and mortality. Studies consistently show that people who lose weight or who weight cycle do worse, in health terms, than people who remain weight stable, even if they’re fat. There was one large study recently that did not show a negative effect of weight cycling, and I have no simple explanation for this. However, a 2012 analysis of over 47,000 ‘overweight’ and ‘obese’ women aged 50 to 79 from the Women’s Health Initiation found that when the weight changes occurred seems to be important – although it still didn’t answer the question of whether more cycling attempts related to more health problems. On the other hand, in an analysis of nearly 30,000 ‘obese’ people from the Aerobics Centre Longitudinal Cohort, the frequency of weight cycling increased the risk of health complications ‘associated’ with obesity by 20%; the only things that had a bigger impact were lifetime weight loss (22%) and low fitness (32%).

To sum up: at best, repeated weight loss attempts won’t make you any sicker, and at worst, they will. The most likely outcome of weight loss attempts is weight gain, so if you believe that fat is inherently bad, then recommending dieting is probably not the way to go. I guess that’s something that TOS would rather not think about.

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