If you know you're going to hit the gym tomorrow, it often affects what and how much you eat today. Here's the science.
We human types play a lot of conscious and subconscious mental games to motivate ourselves to change our behavior or to accomplish some feat or task.
Take for instance my favorite conscious mental game, which is "miss the wastepaper basket and Canada is obliterated by thermonuclear bombs." With such a huge responsibility on my shoulders, I try extra hard to hit the basket. You know, Canada and all.
Then there are the subconscious games. Those are the ones we really have to watch out for. For instance, how many of us think to ourselves, "I'm going to work out tomorrow, so I can really chow down tonight without feeling any guilt"?
We may not really give those exact words to our thought, but we surely act like we believe that an impending workout gives us carte blanche to eat more before a workout. Our reasoning, at least subconsciously, is that we'll "burn off" the extra calories.
As proof, a clever new study found that a "future aerobic exercise session" influences pre-exercise energy intake. In other words, if people know they're going to work out the next day, they end up eating about 20% more during the preceding night's dinner.
Man, that is one stupid game, and just one of many reasons why exercise is largely a failing strategy when it comes to losing body fat.
The Gist of the Study
PhD candidate Asya Baratcu and her associates recruited healthy males who performed cardiovascular exercise at least 3 times a week. The recruits were required to attend a morning meeting where they were informed whether they would rest or perform exercise the following day.
The subjects were then treated to an all-you-can eat breakfast (08:00) and lunch (12:00), along with being given a doggy bag to fill and take back to sustain them during the evening (5:00-11:00).
Those that knew they were going to exercise the next day ended up stuffing their take-home bags with about 20% more food.
Baratcu also offered the exercisers another all-you-can eat breakfast, but this one was presented post workout. Contrary to popular internet belief, the exercisers didn't exhibit increased appetites. Instead, they ate about the same amount as the non-exercisers.
What This Might Mean For You
It seems that the belief that exercise in general burns body fat is deeply entrenched. The men in Baratcu's study believed, at least subconsciously, that the mere prospect of working out the following day earned them the right to eat big the night before. Call it the dietary equivalent of those companies that cash your check before payday.
To be fair, exercise does burn body fat, but the amount is negligible. If you busted your butt on a stationary bike, even telling yourself that Canada would be obliterated in a thermonuclear explosion if you failed to burn 400 calories (according the readout panel on the bike), it still wouldn't "make up" for that scone you had for breakfast, or that extra helping of tater tots you had at dinner last night.
This is especially true if you buy (as you should) the new mathematical computations that show you have to burn closer to 7,000 calories to lose a pound of fat instead of the commonly believed 3500.
So damn those trainers who tell their clients that their anemic little workouts are going to cause them to lose fat. You work out – with weights or otherwise – for health and mobility and to feel good and look good. If you want to lose body fat, your path is clear – restrict processed carbs and practice portion control and don't pretend that your workouts "earn" you the right to eat treats or to eat more food in general.
- Baratcu, et al. "Influence of a future aerobic exercise session on pre-exercise energy intake: preliminary results," Proceedings of the Nutrition Society, October 2018.