When insulin is high, your body can’t burn fat well—even if you drink lots of water.

Hydration in a fasted, low-insulin state significantly enhances fat oxidation compared to hydrated states following carbohydrate intake.

When insulin levels rise, it reduces the breakdown of fat in fat cells by suppressing the enzyme hormone-sensitive lipase.

Insulin reduces fat burning in the blood the same way in obese and lean people, but obese people still burn more fat overall because their bodies are burning fat stored inside cells — not just from the blood.