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You Probably Have No Clue How Much Food You're Burning Off at the Gym

A new study shows that basically, we don’t know sh*t about nutrition and aren’t able to estimate calorie consumption compared to calorie expenditure.
July 22, 2015, 6:00pm
Photo via Flickr user Yasmina Haryono

Ah, eating.

There is absolutely nothing more enjoyable than the eager consumption of food and the nutrition it deems us worthy to absorb. Empires may rise and fall, but there will always be hordes of slack-jawed foodies fervently fawning over prawn prOn. Some might even deign it worthy of say—I don't know—writing about. But as it turns out, humanity as a whole knows far less about everybody's favorite activity than we previously thought.


Sure, we all know that an important part of being able to regulate our weight is to understand calories in and calories out. But let me ask you this: if you exercise for half an hour, how many calories have you burned? And how much food is that equivalent to?

Could you pass this test?

The participants in a recent study in the UK could not. They failed miserably.

In the study, published in the European Journal of Clinical Nutrition, 50 adults and 49 adolescents were asked to exercise for an hour. These people were not novices—they were selected because they exercised regularly at sports clubs for rugby, netball, swimming, hockey, and badminton. What, no kosho? At least tell me there was a bit of Gymkata!

Sigh. Researchers these days. Can't live with them. Can't fathom the secrets of the multiverse without them.

Anyways, the participants were asked to estimate the number of calories they burned based on an existing guide. They were able to do that pretty well.

Here's the kicker, though. The researchers then asked the participants how much food or drink would be the equivalent of the number of calories they thought they had burned. The exercisers were shown 30 squares of chocolate and half-filled bottles of sports drinks to serve as visual cues.

You're probably thinking that the exercisers overestimated the amount of calories they burned and the food they could now eat. But in fact, the opposite was true.


The intrepid exercisers underestimated on average by 500 calories. In other words, they chose less than half of what would have compensated for the calories burned. So if they burned 700 calories playing rugby, when asked to replace those calories through food, they underestimated and chose only about 330 calories of chocolate and 150 calories of sports drink.

Besides the fact that the researchers undoubtedly have a bunch of Cylons on their hands, this is great news, right? If you want to lose weight, then exercise should work—especially if we underestimate the number of calories we need to replace the worked-off ones.

Not so fast. The participants confessed that they would probably have eaten more to replace the burned-off calories if their estimates had been correct.

So, what's the point? What did the study show? Simply this: That we don't know shit about nutrition and aren't able to estimate calorie consumption as compared to calorie expenditure.

One of the researchers, Craig Williams of the University of Exeter, told Reuters that this is the bottom line: "It is not imperative and we should not become too fixated with trying to be as precise as possible, e.g., to the exact 1 kcal (this would be impossible) but [we should] be able to make better overall estimations."

Sounds like code for "Pass the slammin' jalapeño pork sliders!" to me, but what do I know? I certainly haven't spent enough time studying the mysteriously elusive mistress that is eating. Check back in, say, another twenty years or so and we can talk. I just can't guarantee that I'll be doing any exercising.