HEALTH: Why calorie counting is almost useless and often misleading.

A calorie is the amount of energy required to raise the temperature of a gram of water by one degree Celsius. The “calories” we talk about in food are the amount of energy released when that food is burned. Of course the first law of thermodynamics applies to humans, so if you take in less energy than you use, it’s impossible to store that energy (as body fat). But the factors that go into energy balance are many. The body burns and stores energy from different foods in different forms at different times in different people in different ways.

That crudity leads to mistakes, like the idea that 200 calories of Skittles are in any way equivalent to 200 calories of salad. In that way, calories have been weaponized by marketers to claim their ingestible products are innocuous. As Coca-Cola has advertised, for one, drinking soda is fine as long as you exercise enough to burn off those calories. That’s reasonable if it weren’t also true that constant exposure to high-sugar foods changes the way our bodies store energy. It’s like saying it’s fine to insult someone as long as you follow it with a compliment.

Worse still are the loudly advertised “100-calorie” packs of sugar-based edible products. They cause insulin levels to surge, affecting nutrient absorption and subsequent hunger in ways fundamentally different from eating 100 calories of almonds or spinach. That’s so much spinach. It would fill your stomach and please the microbes of your bowel.

Eat more good stuff than bad stuff and don’t worry so much.