We know that protein can provide the body with 4 calories per gram if it is used for energy, like carbohydrates do. Let's say though that a gram of protein has been broken down into aminos for tissue repair, does it still provide the body with the 4 calories?
I THINK that protein would only provide the body with 4 calories IF it's been converted to glucose through gluconeogenesis, but I'm not sure. Has anyone read anything that confirms this?
I think you're mixing up some essentials.
Gluconeogenesis can also be imposed on certain gluconeogenic amino acids, and not just carbohydrates.
Additionally, protein stored as muscle mass is still energy gain (measured in calories). A calory stored is not annulled simply because it's not stored as fat.
If I understand your question correctly, we'll follow the amino acids all the way into making your glutes nice and beautiful (protein used for construction of tissue).
Those amino acids can still be "offered up" as calories via catabolic action. The amino acids are released into the blood and form keto acids, which in turn can be transformed to glucose via your liver.
I'm simplifying, but in that case the amino acids went into your tissue, then because your body wanted them for fuel it removed them, processed them through the liver, and turned them into glucose. This is a very expensive way to make glucose: energy was required for every step of that chain and you just barely came out positive.
This is closely related to a ketogenic diet, whereby cellular energy derives from fat instead of carbohydrates.
If you are trying to count calories for a diet, then NO.
If your body uses some consumed protein for tissue-repair, it's not used for energy, thus you should NOT count it for your overall energy needs if you're counting calories.
That said, it's REALLY hard to estimate how many grams of protein your body will use to repair tissues after a workout. That's why there's such a wide array of estimates on how much protein weightlifter-types need to consume.
Those same muscle-tissues can be later catabolized for energy, if one were starving or atrophying. So in a sense, they still do count, but only if you lose the muscle.
As others have said, you are mixing up some concepts. Calorie counts on food packaging labels are strictly what they would potentially yield as energy. So in that sense yes, 1 gram of protein yields 4 calories (It's actually more like 3.89 or something like that, but 4 calories is the accepted estimate) of potential direct energy use.
But yes, some portion of that goes to digestion, and some portion to muscle repair, skin growth, hair growth, respiration, etc. There really isn't a way to say this gram of protein goes to muscle, this gram of protein to hair, etc. It's an overall count of what is necessary for all biological processes in the body. So you are correct that not all 4 calories per gram of protein are available to rebuild a muscle.
I would not count "protein eaten for muscle construction" towards calories at first. Because at first, it's added as structure, not energy. The resulting muscle structure can later be used (at a calorie cost) as energy, but meanwhile it actually burns calories until then (1 pound of muscle burns about 50 calories per day) and therefore, consuming protein can result in a negative calorie input over time.
An analogy is, making many lawnmowers out of gasoline (which isn't possible obviously,) and running the mowers constantly, feeding them more gasoline. When the gas runs out, each lawnmower can be fed into the others for more.
What is considered calorie intake needs to be purpose-driven. So the answer is contextual. "Calorie Intake" is simple enough. But "meaningful calorie intake" is something that needs context.
