“Oh, it’s OK. I’ll just burn it off at the gym later,” you say, reaching for a cupcake.
Unlike your favorite insulin-bomb dessert, I’m not going to sugar coat it. That’s dumb.
“I’ll just burn it off in the gym later” is one of the biggest killers of fat loss progress the world has ever seen, for several reasons.
First, the logic is horribly flawed. Say you eat a cupcake to the tune of 300 calories, then you “burn it off” in the gym later by expending 300 calories. You just accomplished exactly NOTHING. Your day is net neutral as far as fat loss is concerned. You have made no progress. You can do this for 3 years, and look exactly the same, all else equal.
Second, the math doesn’t work out. In general, people tend to underestimate how many calories are in the food they eat and overestimate how many calories they burn exercising. The average bakery cupcake contains 350-700 calories. A Starbucks flavored mocha-thing contains up to 700 calories. The average 140lb woman has to run at least 4 miles to burn 350 calories (equivalent to a small cupcake). Want to burn off that 700 calorie mega-mocha? You’re looking at about 8 miles of running.
Finally, the physiology doesn’t work either. Even if you did run the 11 miles to “burn off” the mega-mocha, it’s too late. The damage was done in the hour after your consumption when your blood was flooded with glucose and your insulin levels skyrocketed, shuttling the sugar straight into your fat cells. Plaque was deposited in your arteries. Your insulin resistance was raised, making the response even worse next time (diabetes here we come). And that fat you stored? You’ll be lucky to use half of it as fuel when you workout later. 11 miles (or even 4) on the treadmill is going to burn glycogen and break down protein for fuel, not just fat. Afterwards, your hunger levels will be elevated from the exercise, and you’ll compensate for all the calories your burned by eating more. You’ll eat those exercise calories back. And the 1000 you stored earlier from the mocha? Still sitting where you left them.
I’m not even going to get on the subject of how inefficient long-distance cardio is for fat loss… Another day, another post.
What’s the lesson here? You can’t “burn it off later,” and you can’t out-exercise a bad diet. Get your nutrition right!