Most of the stuff you consume, other than the water content, is made up of macronutrients: substances humans require for energy, in relatively large amounts. I’m tempted to say that macronutrients are the nutrients that you can see (as opposed to micronutrients like vitamins or minerals), since the plate that shows the ice-cream scoop of white mashed potato laid beside a sliver of salmon clearly depicts a carb sitting next to a protein (although both foods might have a smidgeon or more of other macronutrients in them—salmon, for example, is about 40 percent fat).

Ta-da, the macronutrients are carbohydrates, fats, and proteins.

What do we mean by “large amounts”? That would be a total of roughly 300 to 600 grams of carbs, fat, and protein for someone who takes in from 2,000 to 3,000 calories per day (and much more for the lumberjacks and mountain guides who eat 7,000 calories per day).