fitness · nutrition

What we know (about body weight) that may not be so

CW: this post offers comments and critiques on a research article whose subject matter is methods for weight loss. The focus of this post is not to endorse any method of weight loss (because I don’t). I’m reframing the area of research as metabolism of body weight– how that works. I then point out how difficult it is to get clarity and confidence from scientific articles about this topic when the researchers as a group are in conflict.

Now, to the post:

Right now, the state of coronavirus research is what I would call the Wild Wild West. There’s not much law and order, shootouts among rival factions are common, and the most vulnerable among us are completely unprotected. But that’s understandable– COVID-19 is less than a year old, so researchers are starting from scratch, and many of them are working while at the same time taking care of patients who urgently need effective treatment.

But no researcher who works on human metabolism of body weight has these excuses, as it were. Trying to understand how body weight changes work– fluctuations up and down, how and when bodies maintain stable weights over time– is a well-established set of research questions with a long history of practices and accompanying literature.

So, what’s the deal here? What do we really know? What’s in dispute among researchers, and what’s just pseudoscientific fat-phobic nonsense?

(tl:dr version– I don’t have a good answer to this question. But, neither do the researchers, and there are reasons why they don’t that aren’t scientific ones.)

In a 2013 New England Journal of Medicine article, a research group took on the task of dividing up myths, presumptions and what they called facts about how body weight metabolism works. Some of their cited “myths” (I’m using scare quotes because whether they are myths is contested) included:

  • how breast feeding affects body weight;
  • how sex counts as physical activity or exercise;
  • how physical activity classes affect body weight;
  • claims about how different eating practices affect long-term body weight stability (see article if you want the details, but they’re not important here).

The researchers considered these to be myths because, according to their analysis, the studies they cite don’t support the above claims.

There’s more to the article (they also talk about what they call “presumptions” and “facts” about body weight, but I’ll leave that to the reader, as they say), but here’s the catch.

Many other researchers and experts didn’t and don’t agree with their conclusions. Why not? There are a lot of issues with their work, but one big one is this:

The primary researchers got a lot-a-lot of funding from Kraft, Jenny Craig, the Knowledge Institute for Beer (no, that’s not a joke), McDonald’s Global Advisory Council (which is also apparently a thing), and yes, Coca-Cola. The list goes on and on, and it’s fascinating reading. Go to the bottom of the article, and enjoy.

Getting serious, though: we know that the money for scientific research has to come from somewhere. Federal funding doesn’t cover all of the needs of all the scientists. Partnering with business and industries is common. And good solid science has been established doing just that.

But: when the connections among scientist, funding source and recommendations to the public get too close, we may be well-advised to take a step back and reconsider. In this case, one of the so-called “facts” cited was that meal-replacement drinks and commercially produced meals were an effective (and safe? not clear) eating practice that could result in lowered body weight (that would be stable? again, not clear). But the funders of this research included companies that would directly benefit from public uptake of this claim.

You might think, hmm. This was seven years ago. Surely this mess has been cleared up by now.

As my friends and I used to say in middle school, “you wish!” Alas, nutrition and human metabolism research (as it relates to body weight) is still in full Game-of-Thrones mode (yes, I switched from a Wild West to the Games of Thrones metaphor in the same article; so sue me…)

Does this mean we don’t know anything? Well, no. We know that there are lots of foods to choose from, that we all have nutritional needs, and there are lots of ways to fill those needs. We know that physical activity has loads of benefits for our well-being.

What about the nitty-gritty details, though? Those, my friends, are most definitely still under construction.

Nutrition and human metabolism research: definitely under construction.

Readers: what are some of your favorite “myths” around this topic? I’d love to hear from you.

One thought on “What we know (about body weight) that may not be so

  1. So great, Catherine! One of the elements of the article that I found so deeply unscientific was the level of confidence with which they outlined their process and findings. A good scientist always has some uncertainties, but even more so with complicated topics involving the cross-section of human biology with human behaviors, society, culture, psychology, etc, etc, etc, which human metabolism absolutely is.

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