Leptin is a hormone produced by fat cells that was first discovered in 1994 by Jeffery Friedman. It is the original “hunger hormone”. Like all hormones, leptin is a chemical messenger. When it comes to leptin, the message that leptin sends is “I’m full.” Leptin is produced by fat cells, travels through the bloodstream, and then works on the brain’s appetite centers, indicating a feeling of fullness. When leptin levels are low, you feel hungry and motivated to search for food.
People with leptin deficiency are hungry all the time and are very overweight. They can get leptin injections and lose a lot of weight without diet or exercise. The problem is that leptin deficiency is extremely rare. In my career, treating thousands of overweight and obese patients, I have never seen a case of leptin deficiency (none of my colleagues have).
So if leptin deficiency is so rare, why all the hype about this hormone? It turns out that most people who are overweight or obese have dysfunctional leptin. In fact, your fat cells make large amounts of leptin. But, since leptin does not work properly, the large amount produced is still insufficient to suppress appetite, causing a person to feel hungry all the time. Indeed, although leptin levels are high, since it does not work properly, the body believes that leptin is low. With leptin resistance, the brain doesn’t get the message that it’s time to stop eating, it’s time to lose weight. Resistance to leptin causes the brain to protect the body from the perception of hunger, even in people who are profoundly overweight.
The following are symptoms of leptin resistance.
- Are you hungry all the time?
- Do you have unexplained weight gain?
- Does your weight increase slowly over time?
- Cravings for comfort foods, fast food, or high-calorie foods?
- Not hungry for breakfast or skip breakfast?
- Do you overeat at dinner?
- Do you have excess body fat?
- Do you have unusual eating patterns or does your diet vary significantly from day to day?
- Does weight loss stop after losing just 5-10 pounds?
- Do you have insulin resistance, metabolic syndrome, prediabetes, or diabetes?
- Do you have arthritis, asthma, lupus, or allergies?
- Do you have high blood pressure or high cholesterol?
- Do you have little sleep, interrupted sleep, or short sleep?
If you answered “yes” to 3 or more of these questions, you most likely have leptin resistance.
Leptin resistance means that your brain thinks it is starving when the opposite is true. Dysfunctional leptin drives appetite and especially cravings for high-calorie foods and junk food. The brain is doing everything it can to avoid starvation.
Leptin resistance also causes a lower metabolism and can lead to a number of other hormonal problems including insulin resistance, type 2 diabetes, polycystic ovary syndrome, low testosterone levels (in men), and thyroid problems.
How is leptin resistance fixed?
Next week, I’ll show you ways to make your leptin work better and more efficiently so you can lose weight permanently.