1. Your insulin levels drop, and stay lower
Within the first few days of intermittent fasting, blood insulin levels fall. This matters because chronically elevated insulin, common in people eating three meals plus snacks across a 14-to-16-hour window, blocks fat burning and drives fat storage. A 2019 study published in Cell Metabolism by Sutton et al. found that early time-restricted feeding (eating within a 6-hour window, finishing by 3 p.m.) significantly improved insulin sensitivity in men with prediabetes, independent of weight loss. By day 30, if the eating window has stayed consistent, the pancreas is releasing less insulin per meal. The body becomes more responsive to what it does release.
