It depends on the level of analysis.
by Mark_It_Zero (2018-12-11 16:12:28)

In reply to: How is "calories in, calories out" wrong?  posted by grnd


If you are speaking generally about needing to operate at a caloric deficit to lose weight, "calories in, calories out" is an easy way to get the concept.


There are two immediate problems with this if we want to be more specific. The first is that your body does not digest all nutrients with same efficiency. Just because you eat something doesn't mean that all of the energy from that food will make it into your system. Fiber is counted on nutrition guides as 4 calories per gram, but the body doesn't digest fiber very well. It is unlikely that you will get those 4 calories into your system. "Calories in, calories out" still works here if you actually know what calories are going in... the problem is that you don't actually know what calories are making it in. Just counting your calories based on the food label won't necessarily give you the accurate number.

The second problem is that the quality of the calories in will impact the amount of calories that will go out. Gut health, digestion and absorption efficiency, fuel source, energy level, mental clarity are all impacted by the calories in. Making sure you have quality calories going in will help maximize the amount of calories you can burn. "Calories in, calories out" still is technically at play here, but it doesn't help you determine how to most effectively get the calories out. "The calories you take in will impact the calories you are able to burn" is a more accurate depiction of the relationship.