Leptin and ghrelin seem to be the big players in regulating
appetite, which consequently influences body weight/fat. When we get hungrier,
we tend to eat more. When we eat more, obviously, we maintain our body weight
or gain that weight back.
Both leptin and ghrelin are peripheral signals with central
effects. In other words, they’re secreted in other parts of the body
(peripheral) but affect our brain (central).
Leptin is secreted primarily in fat cells, as well as the
stomach, heart, placenta, and skeletal muscle. Leptin decreases hunger.
Ghrelin is secreted primarily in the lining of the stomach.
Ghrelin increases hunger.
Leptin resistance is similar to insulin resistance (and they
also share common signalling pathways). Insulin resistance occurs when there’s
lots of insulin being produced (for example, with a diet high in sugar and
simple carbohydrate), but the body and brain have stopped “listening” to