Following the money with the cancer-obesity link

Content note: this post discusses cancer, dieting and fatmisia

The latest research shows that lifestyle factors cause 37% of cancers, with the second-highest cause being “overweight or obesity”. Maybe that’s true, but I’m going to urge a few caveats in interpreting this, as a great question mark is raised by who is funding the research.

Cancer Research UK have received ten million pounds from diet company Slimming World. 

It’s a jawdropping amount of money, and if your eyebrow is raised, rightly so. Funding matters. Now, I’ve no idea of CRUK’s annual turnover, but £10million is generally considered the threshold for a gigantic charity in and of itself, so receiving this amount of money from one income source alone over five years is pretty shocking.

Funding matters. You might have heard of something called a Type A personality: those driven, ambitious individuals who are so go-getting they might give themselves a heart attack. What you might not know is the science behind that is bunk, and a lot of the research was funded by the tobacco industry--who had their own reasons to look for a cause of heart disease that could enter the public consciousness, one that wasn’t the product they’re flogging.

Funding research drives the research agenda. This is why many journals now insist you publish your funders. And it seems like Slimming World have done something rather clever here: removed themselves a step. Technically, Cancer Research UK have funded the research, and are acknowledged as funders in the published paper. It’s just that Slimming World is then, in turn, funding Cancer Research UK. It’s impossible to prove this link, which is a smart move. But that question mark must remain above our interpretation of the research.

I’ve had a read of the published paper, and its methodology is, for the most part, a good, solid systematic review. However, there are concerns about how obesity/overweight is measured and treated.

First of all, weight is looked at entirely through the lens of BMI. This is a huge problem, because BMI can’t measure body fat, and can’t measure where the body fat is, which is important to know. A high BMI can be caused by being tall or short or muscular. It’s still quite popular in research because it’s very easy to measure, but it’s not particularly meaningful as a measure of body fat, and utterly meaningless when it comes to individual health.

The other question mark is far bigger. The research is looking at lifestyle factors: as well as BMI, it looked at smoking, exposure to UV (i.e. tanning and sunbeds), dietary factors such as eating red meat or not enough fibre, alcohol, and so forth. These are changeable lifestyle factors. And then, obesity is lumped in there with it, like including a bunch of grapes in an analysis of apples.

The thing about obesity is, contrary to popular belief, it’s mostly not a lifestyle factor. It’s not just an issue of you eat too much, and if you eat less, you’ll not be fat any more. It’s a lot of things: it can be related to health issues, poverty, medication side effects, genetics, and so on and on.

But who benefits from treating obesity as a lifestyle factor you can easily change, much like smoking? Perhaps, say, somebody selling diets?

As an aside, I also am concerned about other risk factors being treated as “lifestyle factors”, such as occupational exposure and air pollution, both of which can’t really be helped–although that’s more of a problem with the reporting in the media than the research itself.

Which, finally, brings us on to the reporting and press releasing of this story. The media has, obviously, seized upon the obesity link because it is one of their pet stories: those fatties who do it to themselves, why won’t they change? Cancer Research UK’s press release helpfully supplies a toolkit for journalists to trumpet this, including featuring a case study of a woman who was obese, had uterine cancer, learning about how weight and uterine cancer were linked, and then an inspirational weight loss story–which even mentions that she joined a local slimming group! I think I sprained an eyebrow from raising it so much, there.

And meanwhile, Slimming World is falling over itself to encourage people to pay for its diet products and slimming groups.

For a sceptical mindset, it’s really important that we think about funding and its links to research–from what is researched, how it’s reported, all the way through to how it’s reported in the media. It’s healthy to question findings, and with a funding relationship like this, it’s the smart thing to do.


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4 thoughts on “Following the money with the cancer-obesity link”

  1. Cancer research UK’s annual income is in the realms of £650 million, £10 million is a relatively small amount in comparison (~1.5%). They probably make more money from the bake off, and they probably spent wayy more than that on this advertising campaign.

    It is true that hormones circulating from extra body fat are a risk factor for various types of cancer. However, obesity isn’t a singe lifestyle choice and I think that’s where this advertising campaign falls down. It would probably be more helpful to split it up into things like sedentary lifestyle, fruit and vegetable intake, red meat consumption, calorie count – all of which are linked to cancer in and of themselves. Weight takes bloody forever to lose, but making lifestyle changes seems more achievable.

    I’d also like to see a link-up between anti-cancer campaigns and anti-poverty campaigns considering that I imagine it’s difficult for someone relying on a food bank and working 2 jobs to eat a healthy diet.

    1. Yep, it would indeed be much better to look at these individual factors.

      There’s also a huge issue with using BMI as the metric, because that’s so broad brush–for example, it’s known that various places body fat is carried is linked to adverse health outcomes: if it’s carried at the waist, that’s more likely to be linked to negative health outcomes. Ultimately, that’s a far more useful metric than BMI.

      And YES to linking with poverty-based campaigns. And indeed, drawing more attention to structural factors on the whole. For example, that air pollution figure is only going to get worse, but I don’t see much campaigning on the basis of air pollution.

      1. Yeah I think waist measurement are the Next Big Thing in health markers. BMI correlates well with body fat percentage at the population level, though, so for some cancers that are affected by overall body fat (e.g. colorectal cancer in men) it’s still a useful statistic. (I happened to be reading about this earlier. Reference spam:,,,

        Sidenote: while looking that up I came across a paper titled “Men’s reactions to receiving objective feedback on their weight, BMI and other health risk indicators” which was amusing.

  2. Money well spent by Slimming World. I’ve seen no mention of alcohol or air pollution as primary causes of mortality recently. Thanks for your skepticism as always.

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