You can meticulously count every single Jelly Bean or lick of peanut butter you’ve had, then calculate the number of calories you’ve burned to offset them. But this actually hurts your weight loss efforts (and sanity) more than it helps. Here’s why you shouldn’t rely on “calories in” and “calories out”.


At their core, the laws of thermodynamics do not lie: if you use more calories than you take in, you will lose weight, and vice versa. It all sounds simple, except we’ve already discussed why calculating calories in and calories out as if it’s plug-and-chug math can sabotage your weight loss efforts. The truth is that there are numerous variables that will affect both the number of calories that your body will actually get from the foods you eat and the amount that will be expended. These infographics from Precision Nutrition simplify what’s happening in both instances.

On the “calories in” front, the first infographic discusses how not all calories from foods are absorbed. That’s because not all foods are created equal. For example, the amount of fiber a food has or whether the food is cooked could impact the calorie count. Plus, nutritional labels and how much people think they’re eating are both highly inaccurate to begin with.




The problems outlined in the second infographic get really interesting. Basically, you cannot accurately predict how many calories you’ve burned because of variations in individual metabolism, lifestyles (like not getting enough sleep, for instance), genetics, and your history of dieting. Adding to the conundrum are the overblown “calories burned” counts you may see on cardio machines and fitness trackers, along with this nasty bias called the licensing effect, where you are likely to overeat only because you exercised and now think you deserve to eat more.

Clearly, the whole “calories in versus calories out” is not straightforward. This doesn’t mean you should stop caring about calories. Let’s be clear: They still matter a lot, but not to the point of obsessing over neurotic accounting methods and detracting from your enjoyment of life. If you’re trying to lose weight, tracking calories or macronutrients for a while will give you a better idea of portion sizes and how much you’re eating.

In the end, exercise and diet are merely two complementary pieces to the weight loss puzzle. In the words of Dr. Yoni Freedhoff, author of The Diet Fix, “You lose weight in the kitchen, you gain health in the gym.”


Problem With Calorie Counting Calories In and Calories Out | Precision Nutrition