You Don't Use Up Energy, You Make Entropy

Nothing you eat is used up. Energy cannot be destroyed, so for a body holding a steady weight, every joule taken in leaves again - almost all of it as heat off your skin, a little as work done on the world, and whatever is left over is what changed your weight.

So what does food actually give you? Not its energy. Its arrangement. The molecules arrive tightly ordered and leave as scattered warmth, and the difference between those two states is what you consume. The second law is not broken by any of this - your body obeys it by exporting the disorder it produces.

Measured in resting people, that production runs at roughly a third of a watt per kelvin, right now, while you sit still.

Sources, in the order the video uses them:
Resting internal entropy production of 0.18 W per kelvin per square metre of skin, and 4.3 thousandths of a watt per kelvin per kilogram - defined as metabolic heat divided by body temperature. For a 75 kg adult that is about 0.32 W/K, the "third of a watt per kelvin" in the video - Brodeur et al., Annals of the New York Academy of Sciences (2025): https://pmc.ncbi.nlm.nih.gov/articles/PMC12412715/
The same 0.18 W per kelvin per square metre, measured independently at rest before exercise, in 11 middle-aged men - Entropy 25(9), 1290 (2023): https://pmc.ncbi.nlm.nih.gov/articles/PMC10530146/
Schroedinger's 1944 line that an organism feeds on "negative entropy", and his own note on why he chose that phrase over "free energy" (it is in the pinned comment) - Wikipedia, "Entropy and life": https://en.wikipedia.org/wiki/Entropy_and_life

Both measurements were taken in a warm calorimetry chamber (35-40 C), not in an ordinary room, and the figure scales with body size and metabolic rate. It is a resting rate, not a constant.