Let’s shed some obesity myths!

There are a lot of myths and misconceptions surrounding obesity… And then there are also reactive opposite myths and misconceptions, which can sometimes be just as harmful!

To tackle them all would take a book, but in classic 10almonds style, we’re going to put a spotlight on some of the ones that might make the biggest difference:

True or False: Obesity is genetically pre-determined

False… With caveats.

Some interesting results have been found from twin studies and adoption studies, showing that genes definitely play some role, but lifestyle is—for most people—the biggest factor:

• The body-mass index of twins who have been reared apart
• An adoption study of human obesity
• Using a sibling-adoption design to parse genetic and environmental influences on children’s body mass index

In short: genes predispose; they don’t predetermine. But that predisposition alone can make quite a big difference, if it in turn leads to different lifestyle factors.

But upon seeing those papers centering BMI, let’s consider…

True or False: BMI is a good, accurate measure of health in the context of bodyweight

False… Unless you’re a very large group of thin white men of moderate height, which was the demographic the system was built around.

Bonus information: it was never intended to be used to measure the weight-related health of any individual (not even an individual thin white man of moderate height), but rather, as a tool to look at large-scale demographic trends.

Basically, as a system, it’s being used in a way it was never made for, and the results of that misappropriation of an epidemiological tool for individual health are predictably unhelpful.

To do a deep-dive into all the flaws of the BMI system, which are many, we’d need to devote a whole main feature just to that.

Update: we have now done so!

Here it is: When BMI Doesn’t Measure Up

True or False: Obesity does not meaningfully impact more general health

False… In more ways than one (but there are caveats)

Obesity is highly correlated with increased risk of all-cause mortality, and weight loss, correspondingly, correlates with a reduced risk. See for example:

Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease, and cancer: systematic review and meta-analysis

So what are the caveats?

Let’s put it this way: owning a horse is highly correlated with increased healthy longevity. And while owning a horse may come with some exercise and relaxation (both of which are good for the health), it’s probably mostly not the horse itself that conveys the health benefits… it’s that someone who has the resources to look after a horse, probably has the resources to look after their own health too.

So sometimes there can be a reason for a correlation (it’s not a coincidence!) but the causative factor is partially (or in some cases, entirely) something else.

So how could this play out with obesity?

There’s a lot of discrimination in healthcare settings, unfortunately! In this case, it often happens that a thin person goes in with a medical problem and gets treated for that, while a fat person can go in with the same medical problem and be told “you should try losing some weight”.

Top tip if this happens to you… Ask: “what would you advise/prescribe to a thin person with my same symptoms?”

Other things may be more systemic, for example:

When a thin person goes to get their blood pressure taken, and that goes smoothly, while a fat person goes to get their blood pressure taken, and there’s not a blood pressure cuff to fit them, is the problem the size of the person or the size of the cuff? It all depends on perspective, in a world built around thin people.

That’s a trivial-seeming example, but the same principle has far-reaching (and harmful) implications in healthcare in general, e.g:

• Surgeons being untrained (and/or unwilling) to operate on fat people
• Getting a one-size-fits-all dose that was calculated using average weight, and now doesn’t work
• MRI machines are famously claustrophobia-inducing for thin people; now try not fitting in it in the first place

…and so forth. So oftentimes, obesity will be correlated with a poor healthcare outcome, where the problem is not actually the obesity itself, but rather the system having been set up with thin people in mind.

It would be like saying “Having O- blood type results in higher risks when receiving blood transfusions”, while omitting to add “…because we didn’t stock O- blood”.

True or False: to reduce obesity, just eat less and move more!

False… Mostly.

Moving more is almost always good for most people. When it comes to diet, quality is much more important than quantity. But these factors alone are only part of the picture!

But beyond diet and exercise, there are many other implicated factors in weight gain, weight maintenance, and weight loss, including but not limited to:

• Disrupted sleep
• Chronic stress
• Chronic pain
• Hormonal imbalances
• Physical disabilities that preclude a lot of exercise
• Mental health issues that add (and compound) extra levels of challenge
• Medications that throw all kinds of spanners into the works with their side effects

…and even just those first two things, diet and exercise, are not always so correlated to weight as one might think—studies have found that the difference for exercise especially is often marginal:

Read: Widespread misconceptions about obesity ← academic article in the Journal of the College of Family Physicians of Canada

Is Dairy Scary?

Milk and milk products are popularly enjoyed as a good source of calcium and vitamin D.

In contrast, critics of dairy products (for medical reasons, rather than ethical, which is another matter entirely and beyond the scope of this article) point to risks of cancer, heart disease, and—counterintuitively—osteoporosis. We’ll focus more on the former, but touch on the latter two before closing.

Dairy & Cancer

Evidence is highly conflicting. There are so many studies with so many different results. This is partially explicable by noting that not only is cancer a many-headed beast that comes in more than a hundred different forms and all or any of them may be affected one way or another by a given dietary element, but also… Not all milk is created equal, either!

Joanna Lampe, of the Public Health Sciences division, Fred Hutchinson Cancer Research Center in Seattle, writes:

❝Dairy products are a complex group of foods and composition varies by region, which makes evaluation of their association with disease risk difficult. For most cancers, associations between cancer risk and intake of milk and dairy products have been examined only in a small number of cohort studies, and data are inconsistent or lacking❞

In her systematic review of studies, she noted, for example, that:

• Milk and dairy products contain micronutrients and several bioactive constituents that may influence cancer risk and progression
• There’s probable association between milk intake and lower risk of colorectal cancer
• There’s a probable association between diets high in calcium and increased risk of prostate cancer
• Some studies show an inverse association between intake of cultured dairy products and bladder cancer (i.e., if you eat yogurt you’re less likely to get bladder cancer)

Since that systemic review was undertaken, more research has been conducted, and the results are… Not conclusive, but converging towards a conclusion:

• Dairy products can increase or decrease cancer risk
• The increase in cancer risk seems strongest when milk is consumed in quantities that result in too much calcium. When it comes to calcium, you can absolutely have too much of a good thing—just ask your arteries!
• The decrease in cancer seems to be mostly, if not exclusively, from fermented dairy products. This usually means yogurts. The benefit here is not from the milk itself, but rather from the gut-friendly bacteria.

You may be wondering: “Hardened arteries, gut microbiome health? I thought we were talking about cancer?” and yes we are. No part of your health is an island unrelated to other parts of your health. One thing can lead to another. Sometimes we know how and why, sometimes we don’t, but it’s best to not ignore the data.

The bottom line on dairy products and cancer is:

• Consuming dairy products in general is probably fine
• Yogurt, specifically, is probably beneficial

Dairy and Heart Disease

The reason for the concern is clear enough: it’s largely assumed to be a matter of saturated fat intake.

The best combination of “large” and “recent” that we found was a three-cohort longitudinal study in 2019, which pretty much confirms what was found in smaller or less recent studies:

• There is some evidence to suggest that consumption of dairy can increase all-cause mortality in general, and death from (cancer and) cardiovascular disease in particular
• The evidence is not, however, overwhelming. It is marginal.

Dairy and Osteoporosis

Does dairy cause osteoporosis? Research here tends to fall into one of two categories when it comes to conclusions, so we’ll give an example of each:

1. “Results are conflicting, saying yes/no/maybe, and basically we just don’t know”
2. “Results are conflicting, but look: cross-sectional and case-control studies say yes; cohort studies say maybe or no; we prefer the cohort studies”

See them for yourself:

1. Osteoporosis: Is milk a kindness or a curse?
2. Consumption of milk and dairy products and risk of osteoporosis and hip fracture

Conclusion: really, the jury is very much still out on this one

Summary:

• Moderate consumption of dairy products is almost certainly fine
• More specifically: it probably has some (small) pros and some (small) cons
• Yogurt is almost certainly healthier than other dairy products, and is almost universally considered a healthy food (assuming not being full of added sugar etc, of course)
• If you’re going to have non-dairy alternatives to milk, choose wisely!

That’s all we have time for today, but perhaps in a future edition we’ll do a run-down of the pros and cons of various dairy alternatives!