Time to watch my weight?

After reading Peter’s post from earlier this week on the problems with BMI, I thought I should repost the below article from a couple years ago.  

Image by Magnus D

I had an interesting experience at my last physical exam, and I thought it would be worth sharing here on the blog.  Before the physical a nurse put me through an eye test, then took my blood pressure, height and weight.  She then calculated my BMI, and told me that I was in the “normal range” (it was around 24.5).  But, she continued, I was pretty close to the overweight cut-off of 25.0, so I should “watch my weight” moving forward.

I said “un-huh” and sort of laughed inside my head, given that I’m an obesity researcher and we have written the odd post about BMI here on Obesity Panacea.  But the more I talked about the episode with other people, the more ridiculous it seemed.  Here’s why.

BMI is only one aspect of health

As we have said before, weight ≠ health. BMI is moderately useful at estimating body fat, and therefore health risk (especially at the population level).  However, as Peter and I have argued many times, your behaviour matters as much (or more) than your weight when it comes to health.  If you are physically active and eat a healthy diet, you’re likely to be relatively healthy whether your BMI is 22 or 32.  It’s not that weight doesn’t matter at all, but it’s far from the only thing that matters.

(For more on the relationship between BMI and health, I suggest this excellent post by Peter from earlier this week.  Or, for a review paper on the health-benefits of exercise regardless of body weight, click here.)

Context matters

My weight has been stable for several years.  I am (extremely) physically active. I try to limit the amount of time I spend sitting.  And thanks to my wife’s positive influence, I eat a reasonably healthy diet (mostly homemade vegetarian food for breakfast and supper, with leftovers and/or pizza for lunch).  My metabolic health is also fine although, ironically, I had to specifically ask before I was be told my HDL and triglyceride levels.

Why would you counsel a weight stable person with a BMI in the healthy range about their weight (as opposed to their behaviour) anyway?  I’m certainly not the only person to have this experience – here’s what colleague and fellow PLOS blogger Atif Kukaswadia had to say on twitter:

My BMI is around 24.9. My doc told me to “not gain any more weight” for the same reason.

Yet, as our science blogging friend DrugMonkey pointed out on twitter, none of that means that we’re going to be weight stable forever. I’m in my late 20’s, cutting back on my participation in competitive sports, recently married, and nearing the end of grad school.  It wouldn’t be at all surprising if someone in my position were to begin putting on a few pounds over the next few years. In that context, the nurse’s advice seems to make perfect sense.

Except for one (very big) oversight.

How do you “watch your weight”, anyway?

This is really the crux of the problem.  Weight is an outcome, not a behaviour. When someone tells you to watch your weight, what do they really mean?

Obviously one would assume that the nurse meant that I should be physically active and eat a healthy diet.  Except she didn’t say anything about either of those things.  She didn’t ask about my level of activity or my diet (although it had been recorded during an earlier visit), nor did she give me any counseling on what a healthy diet should look like.

What if someone in my position were to take the nurse’s advice and begin dieting to reduce their weight or prevent weight gain (despite being weight stable and already healthy)?  As our colleague Dr Arya Sharma has argued, trying to lose weight is actually a pretty good way to gain weight over the long term.

as I have said before, all weight loss attempts should be medically indicated and anyone attempting to lose weight needs to be warned that they may in fact be increasing their long term risk of becoming (even more) overweight or obese.

I don’t want to be too harsh on the nurse because she clearly meant well.  But a clinical strategy that focuses exclusively on body weight, with no information or counselling related to healthy behaviours, and completely ignoring all context, is almost certainly going to fail (and possibly make things worse than they were at the beginning).

As always, I’m curious to hear what others think.  Has anyone had a similar experience? Have a different perspective on the nurse’s advice?  You can also check out Dr Freedhoff’s thoughts on the issue over at Weighty Matters.


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8 Responses to Time to watch my weight?

  1. Carmen says:

    I had a similar conversation with my NP at my annual physical. My BMI is 24.5, up from around 23 two years prior. That was a purposeful weight gain of muscle and a shift out of an unsustainable, unhealthy food pattern (went completely grain free for a year). My lipid levels had favorably improved and she’d commented positively on my 8-10 hours of physical activity every week. Still, she suggested trying for a 5% of body weight loss to “hedge my bets as menopause approaches.” I’m 35 :)

    If I weren’t a health educator with a degree in nutrition, working on an MPH, I would have felt really discouraged. But I know I’ll be fine.

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  3. Gina says:

    A few months ago I had a Dexa scan that revealed I’ve been losing skeletal muscle mass at a sufficient rate that I meet the Baumgartener calculation for sarcopenia.

    The HCP reported my results to me and suggested that I should lose weight and try to walk for 20 minutes a day. She’d done my intake form with me a few minutes previously and recorded that my weight was 52kg (at that time) for a BMI 20. She’d noticed some kit I had and before the scan, in general discussion, I’d mentioned that I kayak x4 a week and walk about 5 miles in the course of an average day.

    Possibly, this standard health advice comes out by rote and they forget to think about it. When I asked her how much weight I ‘should lose’ and how she proposed that I should do that without compromising my scant lean body mass, she was taken aback enough to blurt: “This might not apply to you, but you are obese”. Well, yes, at 30% body fat, I am – but at present, it’s not clear why I’ve been losing muscle and that’s influenced my body composition.

    I am a TOFI but when part of the reason that you are is because you’re sarcopenic (at a comparatively young age) there is negligible useful guidance. (I know the usual suspicion is that TOFIs have have central adiposity/visceral fat, but I don’t – so much of the advice that does exist doesn’t apply to me).

    • Travis Saunders, Phd, MSc, CEP says:

      That sounds like a very frustrating situation, and a good example of how tricky it can be to apply general health guidelines (e.g. regarding body fat %) to a specific individual’s situation.

      • Gina says:

        I’m following up on the muscle loss as the cause is still unclear. I’m now 49kg for a BMI of 18.55.

        Yesterday, I simultaneously had the “You’re approaching the threshold of being underweight on the BMI continuum” with the, “You need to control your body fat level so you don’t acquire any metabolic disorders” chat. The advice leaflets I received were a mix of, ‘Eat Less, Move More’ and a diet sheet that seems to be based on guidelines from the 80s.

        I accept that BMI may have its uses at the population level but more and more individual seem to be edge cases that I question its usefulness in the settings I’ve experienced – and particularly in light of the Shah & Braverman study.

  4. Kim says:

    Ironically I suspect healthy weight or near healthy weight people are probably advised to lose weight more often than truly obese people. Probably partly because they’re the people who are actually expected to care about their weight and comply (vs. obese people who are presumed to be non-compliant).

    In any case, I was advised to lose weight myself when I was younger and slimmer, when I had a BMI of about 22. I do think that experience coupled with a complete lack of information on healthy diet was a factor — not the only one, for sure — in my eventual weight gain.

  5. Terrie says:

    Anecdotally, I have a buddy who is a very muscular, lean, Iron Man athlete. He gets classified as obese. I have another buddy who is an avid cyclists. Ridiculously fast. He’s a former pro, and still rides like one. He’s classified as obese. If these guys took “obese” away from their healthcare interaction, and felt the sting of that classification, imagine the shame that people who really are obese and unhealthy must feel. There has to be a way to assess overall health that doesn’t distill it to this one measurement.