What is leptin resistance and can it affect your weight?

If you've been searching for weight loss advice online, you may have come across the term ‘leptin resistance’. Some people think it could explain why they always feel hungry, while others wonder whether it could make losing weight more difficult. So, what exactly is leptin, what does it do and is leptin resistance really making it harder to lose weight? We spoke to hormone health expert Dr Nicky Keay to separate fact from fiction.

Leptin is a hormone that's continuously produced by your fat cells. It works alongside several other hormones that help regulate your appetite.¹ The amount of leptin in your blood mainly reflects the amount of body fat you have stored, helping your brain monitor your body's long-term energy stores. As these energy stores change, leptin levels rise and fall too, helping your brain balance hunger with the energy your body needs.¹

Leptin resistance is when your body doesn't respond as effectively to leptin's signals. Put simply, the brain becomes less responsive to leptin's signals about the body's energy stores, meaning appetite may remain higher than expected despite having sufficient fat reserves. This can make it harder to feel full after meals and may leave you feeling hungrier than expected.^2,3

Researchers are still working to understand exactly what causes leptin resistance, so there isn't one clear answer. Scientists believe it's likely to involve several changes within the body that reduce its response to leptin, rather than a single underlying cause.⁵

Leptin resistance doesn't directly cause weight gain, but it may make regulating your appetite more challenging.³ If your brain isn't responding properly to leptin's signals, you may not feel as full after eating, which can make it easier to eat more than your body needs over time. However, leptin is only one part of the picture. Body weight is influenced by many factors such as diet, physical activity, genetics, other hormones, sleep, and overall health.⁶ While leptin resistance may contribute to weight gain or make losing weight feel more challenging, it's unlikely to be the only reason.

Currently, there's no clear criteria or standalone clinical tests for diagnosing leptin resistance.⁷ Instead, healthcare professionals look at the bigger picture, taking your symptoms, medical history and overall health into account rather than relying on a single test. If you're concerned about unexplained changes to your appetite or weight, it's always worth speaking to your GP, who can investigate further and provide personalised support.

You may have come across claims online that a ‘leptin diet’ can help reset your leptin levels or reverse leptin resistance. It generally promotes habits such as:

While there's no magic way to regulate your appetite, healthy lifestyle habits can help support the hormones involved in hunger and fullness.¹⁰ “Let’s not forget about the importance of sleep and exercise – the two other cornerstones of keeping our hormones healthy,” says Dr Keay. “We know that sleep is brilliant for regulating appetite hormones, including leptin, so we should all be aiming for around eight hours of quality sleep a night.”¹¹

Leptin plays an important role in regulating appetite, but it’s only one of many hormones and factors involved in hunger, fullness and body weight. While researchers are still learning more about leptin resistance, there’s currently no evidence that you can ‘reset’ your leptin levels through a specific diet or quick fix. Hormones and body weight are complex and can be influenced by many factors, including underlying health conditions, genetics and your environment. As Dr Keay says, “Get the basics right and your hormones will ultimately follow.”

Disclaimer – This article provides informational advice and is not a substitute for medical care. Working with experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.