Protein - does it wear two hats? (technical input welcome)

CattOfTheGarage

I'm confused about protein calories.

The main purpose of protein in the body is to be used *as* protein - separated into individual amino acids and used to build things.

It can also be entirely broken down and converted to glucose, which is used for energy. Reading up on this in the Web, iI keep coming across statements that this only happens where there are not enough fats and carbohydrates to cover the body's energy needs.

So my question is, does protein *always* contribute to the calorie count, or only when it's not being used to build stuff? If always, how does that work? How can it be used to build while also being burned for fuel? It seems like having your cake and eating it too.

This is just for curiosity. Technical answers and further reading are welcome.

SarahPeters3

The only time any macro nutrient is burned for fuel in the sense youre saying is when you're burning more calories than you consume and your body has to turn to those macro nutrients stored in your body for fuel hence weightloss protein is always going to count for calories, 4kcal to be exact, just as fats and carbs are but each are used in separate ways in the body for different functions.

CattOfTheGarage

Well, not really - carbs and fat are what your body is primarily burning to keep you going, whether you're eating over or under your needs. If you use 1800 calories a day, you need to burn 1800 calories of fuel, which is mainly carbs and fat, either from that day's food or from storage.

So carbs and fat are either burned right away or stored for burning later.

Protein, on the other hand, is either burned right away or dismantled and recycled into body tissues - in which caseit doesn't seem to contribute either to daily calorie needs or to fat stores. That's what's puzzling me.

scottburger104

theoretically it costs your body about 20% of the protein calories to convert it to something you can store.