Calories aren't the whole story: hormones decide where fat goes
September 27, 2026 · 17 min read
Shawn Stevenson, female fitness experts and research on fasting and hunger all emphasize the same thing: insulin and other hormones govern whether fat is stored or released, and meal timing and food quality shape those signals. This shifts fat loss from pure calorie math toward managing hormonal context.
The rules, numbers and steps worth keeping in front of you.
- All agree: calories still matter, but hormones shape what happens to them.
- Stevenson: insulin stores energy and blocks fat burning; glucagon can't work while insulin is high.
- Stevenson: protein burns 20 to 30% of its calories in digestion; fat 0 to 3%.
- Stevenson: processed foods digest quickly and cause higher insulin spikes.
- Huberman: for pure weight loss, you can't escape calories in versus out.
- Huberman: it takes about five to six hours after eating to reach a fasted state.
- Huberman: an eight-hour window cut intake without calorie counting in obese adults.
- Huberman: eat fibrous vegetables first, then protein, then carbohydrates.
- Huberman: a walk after meals blunts the glucose rise.
- Sims: women's cortisol spikes half an hour after waking; food brings it down.
- Sims: women should eat a little before morning exercise and get 30 grams of protein early.
- Sims: under-eating can mean losing muscle and bone while keeping belly fat.
- Caution: much of the timing evidence comes from mouse studies.
- Talk to a doctor before changing meal timing if you have diabetes, blood sugar problems, high blood pressure or a history of disordered eating.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.