What it means
Not all nutrients cost the same to process. Protein has the highest thermic effect, with a sizable share of its calories used up in digestion. Carbohydrates sit in the middle and fat is lowest.
This is one small reason higher-protein diets can help during weight loss. The bigger reasons are that protein helps protect muscle and keeps you full.
The thermic effect is already folded into standard TDEE activity factors, so you do not need to add it separately when using a calculator.
Ultra-processed foods may have a slightly lower thermic effect than whole foods with similar calories, according to small studies. The difference is modest, so focus on overall intake and protein first. Think of it as a small bonus, not a strategy on its own.
Why it matters
It explains part of why protein is prioritized in Sunny Weigh's macro and protein-floor tools.