Leptin: The Hunger Hormone

If my favorite area of nutrition research is hormones, I would then have to say my favorite hormone is leptin. I wrote my thesis on leptin and metabolism. The name leptin is derived from the Greek word 'leptos”,' meaning thin. Leptin is a hormone secreted from fat cells that helps regulate body weight by monitoring hunger and energy storage. The discovery of leptin in 1994 caused a lot of excitement as scientists hoped they could use it to help people control their weight. Leptin helps to suppress appetite, helping maintain a healthy weight. The hormone puts the brakes on hunger by sending a signal to the brain when your body’s energy needs have been met. It does this by letting your hypothalamus know when it’s time for you to stop eating, then it increases your metabolic rate to achieve energy balance (known as homeostasis).

In simple terms, it’s that “I’m full” feeling that happens, so you feel satisfied and done with eating. Conversely, leptin also tells you when to eat – when you are hungry or have too little body fat, leptin signals the brain, and you get the message, “I’m hungry!”

What Can Happen if My Leptin Levels Are Off?

Over time, caloric deprivation contributes to lower leptin levels and slows down your metabolism. Conversely, overeating beyond normal energy maintenance levels harms your body’s ability to distinguish whether your fat levels are too high or too low. In the case of overeating or being consistently exposed to increased leptin levels, your body can become leptin resistant (a condition similar to insulin resistance). When the leptin signal isn’t functioning correctly, you can overproduce leptin, leading to leptin resistance. That’s one reason why you eat…and eat…and eat, but your brain never gets the memo to stop.

Leptin Resistance

Yes, It’s confusing because people who have more body fat have higher leptin levels. So, what’s the problem? Leptin resistance means you can have a lot of body fat, making a lot of anti-hunger hormone leptin, but it isn’t working correctly. So, instead of a drop in appetite, your brain might think you are starving, making you hungrier—a vicious cycle.

How Do I Know if I’m Leptin Resistant?

Leptin resistance takes on different forms: carrying too much weight, constant cravings, needing to snack throughout the day, or a diet high in sugar and grains. Excess fat in the midsection can indicate leptin resistance and significantly affect the blood’s overall leptin levels.

So, How Much Leptin Should I Have?

Leptin levels can vary throughout the day and can fluctuate with weight. In general, 4-25mcg/L is a healthy leptin range for women, and 1-9mcg/L is a healthy range for men. Because fat cells produce leptin in proportion to their size, obese people also have very high leptin levels compared to their thinner counterparts. Furthermore, the blood’s leptin concentrations are typically lowest mid-day and highest after midnight, so the amount of leptin you have can vary throughout the day and with weight.

How Do I fix my Leptin?

To maintain an optimal level of leptin:

Eat more anti-inflammatory foods because inflammation is one of the causative factors in leptin resistance.

Eat plenty of protein, healthy fat, and fiber. Cut down on high glycemic carbs such as grains and sugar.

Enjoy three meals/day, spaced four to six hours apart: Eating three meals per day will keep leptin levels stable. Avoid crash dieting or calorie restriction.

Avoid snacking: Snacking between meals causes your insulin to spike, which keeps your leptin levels elevated. In some cases, that can lead to leptin resistance. By allowing four to five hours between meals, you allow your body to manage your leptin response better.

Try not to eat too late. Eating after 8 p.m. has been associated with higher leptin levels and more weight gain in various research studies.

Try gentle Intermittent Fasting: leptin levels also drop during short-term fasting and return to normal after eating, making it one reason that IF is a painless but powerful way to retain leptin sensitivity.

Get that beauty sleep. Sufficient sleep helps with your ghrelin (sleep) hormone, which works closely with your leptin hormone. Shorting your sleep does a real number on your hormones.

Exercise: High-intensity exercise seems to have an improved effect on leptin than prolonged steady-state exercise. To fully understand the full scope of the hormonal effects of exercise, more research is required.

Another way to reset your leptin levels is to remove fructose from your diet. The studies that link fructose and leptin resistance show that fructose blocks leptin action most likely by blocking leptin entry into the brain. While this doesn’t mean eating fresh fruit fructose is terrible, limit yourself to a couple of fruit pieces a day.

Don't fall for so called "leptin supplements." Researchers learned that leptin supplements don't work since they can't get past the blood-brain barrier and are metabolized by the body.

Many of the strategies I write about to keep insulin, leptin, and ghrelin optimized are the same. These hormones are so interconnected that they all benefit from these nutrition and lifestyle shifts.

When leptin is balanced, you may notice you don’t need to rely on willpower to lose weight (never works), reduced mood swings, a lack of cravings, and decreased appetite, increased metabolism, and increased energy levels.