The first time I ran 100 miles in a week, I was ravenous. I wanted to eat everything in sight, and I especially craved fat.
That was 5 years ago, and I’ve seen my body adapt over the years–not only in terms of being able to tolerate those distances better, but also in terms of calories needed to run those distances.
Last summer I peaked at 95 miles; this summer I peaked at 74 miles. I can honestly say I wasn’t nearly as hungry as I was the first time embarking on those distances.
I think most people overestimate how many calories they need when training for a marathon. I see a lot of mindsets that say, “I just ran 20 miles, let me eat 3 donuts, a large pizza, and an entire tub of ice cream.” Obviously that’s an exaggeration, but I do think people have the mentality that they can eat whatever they want and indulge more often than they really should.
I used to estimate that for each mile I ran, I burnt about 100 calories. However, as your fitness improves, your body becomes more efficient at using calories to run the same distances, which means over time you will be burning less calories each mile.
I don’t know how accurate my GPS watch is, but take for example this recent 20 miler I did. My watch says I burn 962 calories during 3 hours of running. That’s less than 44 calories per mile!
How many calories your body burns is very dependent upon age, weight, height, and how efficient your body is at burning calories, so these are all rough estimates!
Over the years of training, I’ve gotten better about listening to my body and determining when I am truly hungry versus wanting food ‘just because.’ While it would seem that if I did a long run Saturday morning, I would feel hungry the rest of the day. In reality, most of the time if I do a long run on Saturday morning, the hunger doesn’t hit me until the next day on Sunday. I don’t know the science behind this, but I have heard other runners comment the same thing. I also notice my hunger surges during a day off. It’s as if my body is saying, “Finally! A break, let’s recover and make sure you eat enough!”
All in all, I think it is okay to indulge every once in a while, but I feel like some people use any run as a reason to indulge. Ultimately listen to your body (really listen to your body!) and remember food is fuel.
Let it be noted:
I write these things with some caution because I know that food is a sensitive topic for many people who have dealt with eating disorders in the past. I definitely think you should be fueling your body with enough calories to power through tough workouts and long runs. I am of the belief that food is fuel, and I think most people should aim for an 80/20 split with 80% of their calories being nutritious and 20% being not-as-healthy, so you don’t feel starved or deprived of the unhealthy foods. At the end of the day, you know your body the best, so take care of it and treat it well.
