Leptin – Regulating the Body’s Set-Point
Leptin is a master hormone, like insulin. Its major role is to maintain your current body weight. Leptin, along with ghrelin, may be the major regulators of the body’s “set-point”, seeking to restore body fatness when you lose weight.
Leptin affects many areas of the brain as well as the function of other hormones and neurotransmitters. In turn, it is also modulated by other chemical messengers.
Leptin is produced by fat cells. So, as you gain fat, you produce more leptin, which circulates in the blood stream and travels to the brain. Obesity is associated with high leptin levels and leptin resistance, a condition that is similar to the resistance seen with insulin.
Leptin tells the brain, “I’m full”, turning off appetite. If your fat cells have recently been fed and “feel fuller” compared to their recent set-point, then you will be less hungry. If you starve, your leptin levels decrease from the set-point, triggering appetite. This phenomenon is one reason why many of us have trouble maintaining a diet for any length of time. The body is trying to maintain the status quo. The fat cells will not give up their fat easily!
If you are leptin resistant, your brain may not respond well to the leptin signals. You may continue to feel hungry and think about food even though your leptin levels remain high. Leptin resistance increases with body fatness.
When you lose weight, leptin levels decrease. Initially, this will trigger more hunger. But if the weight loss is maintained, you will have improved leptin sensitivity (the opposite of leptin resistance). The weight loss will be easier to maintain over time, and you will establish a new set-point.
Sleep seems to affect leptin levels. A lack of sleep leads to lower leptin levels in the short term. Lower leptin levels, in turn, increase hunger. Over time, reduced sleep (less than 7 hours/night on average) can lead to weight gain as well as leptin and insulin resistance.
Many genetic variations and abnormalities involved in leptin metabolism and leptin receptors may account, in part, for the wide individual differences in body size.
Researchers have not yet identified ways to use leptin treatment to help people lose weight. Diet, exercise, and a good night’s sleep are still the best ways to overcome leptin resistance and lose weight.