12/27/2025
Leptin is one of the hormones your brain uses to understand how much energy you have stored. When leptin is at the level your brain expects, things run smoothly — hunger stays calmer, metabolism sits a little higher, and you often feel more energetic overall.
In other words, when leptin is steady, your brain feels safe.
It isn’t worried about famine or starvation, so it lets your body function the way it’s meant to.
This sets the stage for why leptin becomes such a big factor during weight loss — because when those levels fall, the brain reacts fast.
Understanding what leptin does when everything is “normal” makes it easier to understand what happens when it drops.