Macro partitioning

Higher carbohydrate intake is associated with a decreased Free Leptin Index (FLI), while higher dietary fat intake is associated with an increased FLI, independent of total energy and body fat.

The ratio of free leptin to its binding receptor (FLI) shifts based on what you eat. Eating more carbohydrates tends to lower this ratio, while eating more fat tends to raise it, even if your total calories and body fat stay the same.