Leptin is a hormone secreted from fat cells that helps to regulate body weight. The name leptin is derived from the Greek word ‘leptos”,’ meaning thin. Leptin helps with regulating food intake and energy storage. It helps to suppress appetite, and this helps maintain a healthy weight. Leptin puts the brakes on hunger by sending a signal to the brain when your body’s energy needs have been met, and it controls energy expenditure over the long term.  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 full feeling that happens, so you feel satisfied and are 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.[1]

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. Also, excess fat in the midsection can indicate leptin resistance and significantly affect overall leptin levels in the blood.

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. That said, women typically have higher levels of leptin in their blood than men, and because fat cells produce leptin in proportion to their size, obese people also have very high levels of leptin compared to their thinner counterparts. Furthermore, leptin concentrations in the blood 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 Reset my Leptin?

To maintain an optimal level of leptin, you should:

Since inflammation is one of the main causative factors in leptin resistance, eat more anti-inflammatory foods whenever you can. 

Eat plenty of protein, healthy fat, and fiber.

Enjoy three meals/day, spaced four to six hours apart: Eating three meals per day will keep ghrelin and leptin levels stable. During crash dieting or calorie restriction, ghrelin levels increase, and poor food choices and cravings will increase.

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 reset your leptin response and avoid leptin resistance.

Exercise every day: High-intensity exercise seems to have an improved effect on ghrelin and leptin than prolonged steady-state exercise, although to fully understand the full scope of the hormonal effects of exercise, more research is required. We know that regular physical activity improves overall hormonal balance, weight, and a sense of wellness through functional medicine.

Eating after 8 p.m. has been associated with higher leptin levels and more weight gain in various research studies.

Eight to ten hours of restful sleep

Avoid artificial sweeteners, which stimulate the pleasure center in the brain, however without the additional calories, keep leptin levels low and ghrelin levels elevated.

Getting sufficient sleep helps with your ghrelin (sleep) hormone, which works with your leptin (hunger) hormone. As I always say, hormones act like a big dance party.

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 is terrible, limit yourself to a couple of fruit pieces a day. 

Many of the strategies I write about to keep insulin, leptin, and ghrelin on your side are the same. These hormones are so interconnected that each will benefit from these lifestyle shifts.

When leptin is balanced, you may notice better skin, reduced mood swings, a lack of cravings, and a reduction in appetite—not to mention an increase in energy levels and better sleep.

Radic R, Nikolic V, Karner I, et al. Circadian rhythm of blood leptin level in obese and non-obese people. Coll Antropol. 2003;27(2):555-61.

Considine RV, Sinha MK, Heiman ML, et al. Serum immunoreactive-leptin concentrations in normal-weight and obese humans. N Engl J Med. 1996 Feb 1;334(5):292-5.

Radic R, Nikolic V, Karner I, et al. Circadian rhythm of blood leptin level in obese and non-obese people. Coll Antropol. 2003;27(2):555-61.

Christina C Wilson MS, CNS, LN


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