Does Exercise Fight Obesity Or Not? An Explainer


Today, an editorial arrived in the latest edition of the British Journal of Medicine insisting that diet, not exercise, was key to controlling obesity with the title of It is time to bust the myth of physical inactivity and obesity. Which was just a little provocative! Unfortunately, it’s also an opinion piece about something we already know. Here’s what’s going on.

So, wait, exercise won’t help me lose weight?

Exercise can help you lose weight, but here’s the problem: Most of the calories you burn, you burn by just kinda existing. For example, if you jog at a steady pace for an hour, you burn about 400 calories. Just sitting on your butt, reading intelligent articles by dashing internet writers, will burn about 1,200 over the course of a day. More if you use one of those standing desks.

Similarly, you can get the same amount of exercise just by doing day-to-day stuff like mowing the lawn or walking to work. In fact, some recommend you take 10-minute exercise breaks throughout the day instead of hitting the gym for an hour.

If the human body’s good at burning calories, why aren’t we all carved gods?

The short answer? Even if you eat to a calorie goal, if you’re eating crap food, it’s still going to kill you. As the editorial itself notes:

Up to 40% of those with a normal body mass index will harbour metabolic abnormalities typically associated with obesity, which include hypertension, dyslipidaemia, non-alcoholic fatty liver disease and cardiovascular disease… members of the public are drowned by an unhelpful message about maintaining a ‘healthy weight’ through calorie counting, and many still wrongly believe that obesity is entirely due to lack of exercise.

So, why the hell am I reading this on a treadmill?

Because exercise helps prevent a whole host of terrible diseases, like certain types of diabetes and cancer. The issue isn’t that exercise is useless; the issue is that exercise isn’t going to help you lose weight on its own unless you also watch what you eat. The upside of this is that now you can torment that jerk who runs marathons while juggling kettlebells and then insists that makes it okay to hork down an entire pizza: He’s in the same boat as the rest of us.

What are they blaming for the “obesity epidemic” instead?

Sugar, mostly. To be honest, the editorial gets a little too “conspiracy theory” for me at this point, there’s a lot of ranting about public relations and food companies misrepresenting science to make themselves look good. And that does happen! Then, the smoking comparisons roll out.

That said, they’re not wrong about sugar; it’s fine in moderation, but it’s fairly well accepted at this point that fructose has a negative interaction with leptin, the hormone that tells you that you’re full. Basically, if you drink a soda, you’ve consumed about 200 to 300 calories, but your brain doesn’t understand that and will tell you to eat more. The problem should be obvious.

So, what should I do if I want to lose weight?

Well, for one, exercise. Like we said, it’s good for you, and it doesn’t have to be a gym visit: Even just walking more will help. Two, in general try to cut down on the junk food; you don’t have to be a crunchy vegan, just eat more veggies and fewer Cheetos. And three, sort through what’s medically important to you and what’s just marketing BS; for example, a six-pack can actually be incredibly unhealthy.

In short, what you’ve heard is true: Eat right, exercise, and don’t torture yourself over how you could be doing better. This is one of those situations where what you do is more important than how you look at the end of it.