Study Spotlight: A License to Eat?

By: Andrew Jagim

A lot of people treat exercise, specifically calorie expenditure, and food (calories consumed) as an exchange program rather than mutually exclusive habits that can both offer a variety of benefits.  What I mean by this is that a lot of people will complete a workout and see that they burned ~500-700 calories during that exercise session; then later on at their next meal they may rationalize in their mind that a larger meal is okay because they "earned it" or burned "X" amount of calories during their workout.

I also see the reverse happening at times when people accidentally overindulge at a meal and then say they have to go to the gym to "work it off" and in a way use exercise as a form of punishment or negative reinforcement regarding their dietary habits.  Now a lot of this is just based upon the mental games that people play in their mind and how they may have developed inappropriate relationships with food and exercise but is there any scientific evidence to support that this actually happens?  A recent study was published that investigated the dynamics between exercise and dietary habits.

What did they do?

Researchers had 70 healthy male and female participants complete a set amount of exercise (equivalent to approximately 120 calories worth of activity) but were told by the researchers that they burned: A) 50 calories; B) 265 calories or C) Received no information about calories expended. Following the exercise bout, subjects were presented with an ad libitum test meal and were advised to eat until they felt satisfied.  Reports of calories consumed during the test meal and ratings of hunger were monitored following the exercise bout and test meal.

What did they find?

Subjects consumed significantly more calories during the test meal when they were informed that they had burned 265 calories during the exercise bout compared to the 50 calorie condition and control. 

Further, ratings of hunger were significantly lower in the 265 calorie information condition than in the 50 calorie condition following the test meal.

Take Home Message

The results of this study support the idea of a "license to eat" to situation; meaning that when individuals think they burned a lot of calories during a workout they feel as though they have a free pass to eat more food following that exercise trial and may think of the food as a "reward" of their hard efforts which unfortunately may off-set any benefit they may have received from the bout of exercise itself in terms of energy balance. 

It's important to understand the benefits of exercise outside of calorie expenditure. Treat food as a tool to accomplish your exercise and health goals rather than a reward or punishment. Understand the value of eating nutrient-dense, high quality food options (the majority of the time) while still allowing for the occasional indulgence here and there because we are humans and it's okay to enjoy life!  It's worth mentioning that it is normal to feel more hungry after strenuous exercise and/or training, particularly in more of an athletic setting and therefore sometimes increased food consumption is warranted to promote optimal recovery. In athletic populations who are training 2-4 hrs per day multiple days per week it is important for them to increase food consumption post training and throughout the day in order to prevent declines in body weight, particularly lean muscle mass and ensure proper progression through their training program.  However, for the general population who may be more focused on weight management and are intentionally striving for a daily caloric deficit to promote weight loss they must "exercise" (see what I did there?) caution when consuming meals post-exercise to that they don't overindulge and off-set their calorie expenditure.

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