How the two appetite hormones move in opposite directions
Leptin and ghrelin are often described as a paired system because they tend to push appetite in opposite ways. Leptin is secreted by fat cells in rough proportion to fat mass and signals satiety and energy sufficiency to the brain. Ghrelin, made largely in the stomach, signals the need to eat. In a sustained energy deficit, circulating leptin falls within roughly one to three days as fat stores shrink and energy intake drops, while ghrelin tends to rise, a combination that increases the drive to eat.
Leptin tracks longer-term energy stores while ghrelin responds more to short-term meal timing, so they operate on different timescales rather than as a simple mirror image.
What a refeed does and does not restore
A short period of higher carbohydrate and overall calorie intake, sometimes called a refeed, can partially raise leptin back toward baseline because leptin responds to both fat mass and recent feeding, especially carbohydrate. The rebound is partial and temporary, and it does not fully reset the appetite system during an ongoing deficit. Individual hormone responses vary considerably. This is general educational information, not medical or dietary advice; consult a qualified professional before changing intake for a health reason.