Let’s start with the basics of what leptin is and what it does. It is known as the “satiety hormone” and this might help give you an idea of what it does. This is a hormone that inhibits hunger to help regulate energy balance. Here’s the thing about this type of hormone, it has an antagonist, or a hormone that does the exact opposite, that is to make us feel hungry. The body works in this way to maintain a balance. This hormone is called ghrelin, the “hunger hormone”.
The problem with diets is that people think of them as a short-term plan that they will abandon once the fitness goal is achieved. They do not really make any lasting changes to their lifestyles. The other issue is that whenever you apply certain stress to the body, the body will always respond to compensate for any loss. In other words, if you make your body hungry, it will react by finding mechanisms to keep the energy balance, therefore, making you hungrier.
When leptin was first found to make fat mice lose weight, it was regarded as the “holy grail” of weight loss. Results within the public proved that the pill worked in mice much better than in humans. In fact, it was found that leptin works only in those (mice and humans) that were genetically deficient in leptin, which makes up only 5-10% of obese people.
Leptin is mainly activated when you eat fat. In other words, the more fat you have, the more leptin you will produce and the less hungry you become. In conclusion, the more leptin, the better.
Sounds like the final solution, doesn’t it. Experience tells us it does not really work like that. Unfortunately, a person can become leptin-resistant, something like getting the signal disrupted. You eat more fat, you produce more leptin. More leptin means mixed signals to the brain. The brain thinks you are starving, so it makes you hungrier. You eat more, more fat, and so on.