“License to eat. Information on energy expended during exercise affects subsequent energy intake” (Duncan Et Al, 2016)
This above means that it is looking at, if we are told the number of calories that we’ve expended during an exercise session (how many calories we’ve burned) well does this affect how much we then go and eat after we exercise?
A study that was taken in which 70 healthy participants took part in where they performed 120 calories worth of exercise followed by a snack that they could get from the buffet where they was in which they could get foods from this buffet such as cookies, crisps and orange juice.
These people worked out 3 times. One time they were told they worked off 5 calories even though they burned the 120 calories. Another time they were told they actually had burned 120 calories and another time they were told that they had burned 265 calories.
Now you would expect that the more calories than you burn, the hungrier that you are. The participants did the same amount of work in all the 3 workouts but the thing that changed was the information that they were given (i.e how many calories that they had burned). Was it 5 calories, 120 calories or 265 calories?
The participants ate more food (the cookies) when they were told that they had burned 265 calories.
Duncan Et Al came to the conclusion that these results were a poor interpretation that higher energy expenditure information (being told that you’d burned more calories during your workout session), this provides participants with a greater of what they called ‘license to eat’ when palatable foods are accessible. So in the real world this, in fact, means- e.g, lets say your treadmill or Fitbit watch tells you that you’ve burned a certain amount of calories, subconsciously because you’ve been told how many calories you’re going to burn or it says that you have burned, people naturally go and eat more food to compensate for this, it’s like they are treating themselves for burning more calories, even when they actually haven’t done more work. When we think back to the blog about NEAT where we said that things like FitBit can be inaccurate, this is why we can have a problem because we can have people who are going to exercise and thinking that they’ve burned more calories than they actually have and then they are going treating themselves by eating even more calories than they normally would. We think that we are consuming 2000 calories, so if on a rest day we would normally eat 2000 which say is your weight maintenance however we do a bit of exercise and we think ‘right I’ve done 300 extra calories worth of work in that workout’, I’m now in a 300 calorie deficit and I am losing weight but subconsciously we increase the amount of food we’re eating based on that information and we then wipe out our calorie deficit and once again even though we have increased our calories in and so our weight remains stable, we can now start to see how some of these can cause problems. Therefore the license to eat as well as underreporting our food intake as well as over-reporting the amount of work that we are doing, you can start to see why some individuals think that they’re working very hard, dieting hard and they’re not losing weight, it’s because a lot of these small things start to add up in which we have basically wiped out our calorie deficit.
When we start looking at how cardiovascular exercise impacts appetite, on the whole, exercise is a great way to increase energy expenditure (how many calories we burn through exercise) (Schubert Et Al, 2013), however, there are huge individual differences.
In this study done by Finlayson, 2009, they got participants to do 50 minutes of low-intensity exercise i.e walking on the treadmill. During this time they got asked to burn 100 calories worth of work, the study shows that some of these people ate less when they exercise and some of the other people ate far more. Some of these individuals overate by 300-600 calories but they had only done roughly 100 calories worth of work but because they had exercised and their appetite has gone up massively well then they went and ate them 300-600 calories. These people then think that they’re exercising and subconsciously go away and eat more and then they gain weight because they have put themselves in a calorie surplus whereas the other individuals in this study actually ate between 300-600 calories less than they normally would so not only are they going and exercising and burning an extra 100 calories, they are actually taking in 600 calories less, so therefore these individuals are going to see rapid weight loss.
If we compare the two groups of people in this study, these two different groups of individuals have both done the same exercise programme of 50 minutes of a low-intensity exercise but the results are that their appetites are very different. This is why we always have to take exercise, training and nutrition as an individual basis.
A way to think of it is this- When it comes to calories that we spend in pence (exercise) and we earn in pounds (food) and it soon becomes easy to save (body fat), so think of it as a bank balance, the more we have in our bank the fatter that we are going to get and the more body fat we are going to store. We spend it in pence, it’s hard to spend during exercise but it’s easy to earn it through food so if we think how many calories it actually takes to burn 200-300 calories worth of work in the gym/whilst exercising, it’s exceptional, however we can do this very quickly with something like a Mars bar, a bottle of coke etc and this is just before we have even left the gym.
So this idea of a license to eat brings up the question, can you out exercise a bad diet?
Unless you are exercising a massive amount then probably not.
Things to remember are-
To be aware if you are compensating with your eating
Don’t let 1 hour of exercise impact the other 23 hours (your NEAT)