Leptin is a hormone made by fat cells (adipocytes) that acts as a communication line between your body fat and your brain, specifically the hypothalamus.
What Leptin Does:
Leptin signals to your brain that you have enough energy stored in fat cells and don’t need to eat. As fat stores increase, leptin levels rise, which should decrease appetite. Conversely, when fat stores decrease, leptin levels drop, increasing hunger. This system helps maintain stable body weight.
Leptin Resistance:
In some people, particularly those with obesity, the brain becomes resistant to leptin’s signals. Even though leptin levels are high, the brain doesn’t receive the ‘stop eating’ message. This is called leptin resistance and can make weight loss challenging. Factors contributing to leptin resistance include chronic inflammation, high insulin levels, and poor sleep.
The Leptin-Ghrelin Balance:
Leptin works opposite to ghrelin (the ‘hunger hormone’). Ideally, when leptin is high, ghrelin is low (you feel full), and vice versa. Sleep deprivation disrupts this balance, decreasing leptin and increasing ghrelin, which can lead to increased appetite and weight gain.
