What Does Leptin Do?

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Leptin is a cell-signalling hormone vital in the regulation of appetite, food intake and body weight. Studies have shown that an absence of leptin in the body or leptin resistance can lead to uncontrolled feeding and weight gain.

Mechanisms and actions of leptin

Leptin acts as a hormone that modulates the size of the adipose tissues in the body. It regulates food intake and body weight. Leptin also acts on specific receptors in the hypothalamus to inhibit appetite through both counteractive and stimulatory mechanisms:

  • Leptin counteracts the effects of a feeding stimulant released in the gut called neuropeptide Y as well as the effects of a cannabinoid neurotransmitter called adandamide which stimulates appetite.
  • Leptin also promotes the synthesis of an appetite suppressant called α-melanocyte-stimulating hormone

When fat mass decreases, the level of plasma leptin falls so that appetite is stimulated until the fat mass is recovered. There is also a decrease in body temperature and energy expenditure is suppressed. By contrast, when fat mass increases, so do leptin levels and appetite is suppressed until weight loss occurs. In this way leptin regulates energy intake and fat stores so that weight is maintained within a relatively narrow range.

Leptin also plays an important role in regulating and modulating the onset of puberty. For example undernourished and thin women take longer to reach puberty than heavier girls. Thin girls often fail to ovulate or release an egg from an ovary during menstruation cycles. Reproductive growth and fat stores are therefore vital in the regulation of reproduction.

Researchers know that leptin plays a role at least to some degree in the onset of puberty as individuals with an absence of leptin or a lack of response to leptin do not experience puberty, with their bodies remaining pre-pubescent for life.

Further Reading

Last Updated: Jun 20, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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  1. Catherine Jackson Catherine Jackson United States says:

    I think I've read as much as I can read about Leptin & the role it plays in controlling weight. I'm hoping you can answer a few questions. I am a 58 year old post menopausal female who was a size 4-6 my entire life until I started menopause at 45, post menopausal at 50. I am now at least 50 lbs overweight. I rarely have an appetite, & I usually eat one small meal a day. I bet I don't even eat 1,000 calories a day. I rarely eat sugar, I drink at least one cup of green tea a day, straight up, no sweetener. I confess I do not exercise, but I'm definitely immobile. Most of my weight is Belly Fat. I cannot understand why I can't lose weight, especially after reading, once again, the Leptin Hormone & it's purpose. Some days I don't eat at all. I have also read in my research that NOT eating causes you to gain weight as well. Do you have any information to offer on my situation? I enjoyed reading your papers about Leptin, as I first researched it about 3 years ago. Thanks, Cat

    • KeyonEats KeyonEats Canada says:

      If you want to lose weight as an older women Keto is a great option, but in general, if you starve yourself (only eating 1000 calories a day) your thyroid slows down because you condition your body to think there isn't enough food around. Instead, try eating at your maintenance calories than fasting for 24-48 hours 1-2 times a week. Garunteed you will lose weight

  2. Catherine Jackson Catherine Jackson United States says:

    I'm definitely NOT immobile. So sorry about that mistake. Cat

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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