This content was reviewed and approved for its accuracy on 28/05/2021 by Professor Frank Joseph

Photograph of Professor Frank Joseph, weight loss expert for myBMI

Ghrelin and Leptin 

Ghrelin and leptin are both hormones that are produced by your body that have a significant effect on appetite. We need both of these hormones in the right levels to be able to tell us when to start and stop eating, and if the levels aren’t controlled or balanced, it could lead to weight gain or weight loss. 

Ghrelin increases your appetite, whilst leptin reduces it.  

What is ghrelin? 

Ghrelin is a hormone that’s produced and released mostly by the stomach, but also by the small intestine, pancreas and brain. Ghrelin can increase appetite, food intake, and fat storage, and is also known to act on parts of the brain that are involved with reward processing. 

There are various things that can affect ghrelin and how it works, such as the types of foods that you eat. For example, it has been proven that protein and certain carbohydrates (whole grain and low GI carbs) are able to reduce the production and release of ghrelin more than some other food groups, such as fats.  This is part of the reason why people that are trying to lose weight are often recommended a diet high in protein and fibre, as both of these foods are able to stave off hunger for longer. Semaglutide can also help with regulating your appetite by slowing down the digestive process, so food stays in your stomach and intestines for longer, making you less hungry. Studies show that there is a complex interaction between ghrelin and GLP-1 to regulate food intake but the exact mechanism of action is still unclear.


What is leptin? 

Leptin is a hormone that’s produced by your fat cells, and it helps to decrease appetite. It helps in sending signals to our brain to let it know that the body has enough energy reserves. This then reduces hunger (and ghrelin levels deplete), and keeps us feeling satisfied. Leptin also plays a role in your metabolism and energy expenditure, as it rises and falls in line with how much energy we need.  

When leptin levels are high, we’re generally satisfied. Its therefore important to keep a check on how satisfied you feel, and not eat again before you need to. This is where the hunger scale can be useful in helping you recognise your body’s cues and what it needs. This can help to reduce over-eating, and should help in regulating levels of the hormone, as if you store more fat due to over-eating, you’re more likely to experience increased levels of leptin, as more fat cells = more leptin production. However, this isn’t always a good thing. 

Leptin resistance  

Generally, the more fat you have, the higher your leptin levels will be. However, this doesn’t always mean that people with excess weight have a reduced appetite – in fact, it’s quite common for people with a high BMI to experience more hunger. This happens when the signal that leptin sends to the brain doesn’t work properly, a condition which is known as leptin resistance.  

Leptin resistance isn’t fully understood yet, but it is known that obese people are more resistant to the hormone, and it may even be a contributing factor to obesity, as clear signals are needed in order to respond to what the body needs.  

Unfortunately, if nothing is done with leptin resistance, it can lead to a vicious cycle, or a “catch 22” situation, whereby you eat more because you’re resistant to leptin, which leads to more fat which produces more leptin which you become increasingly resistant to.  However, there may be certain things that you can do to reduce your leptin levels. Reducing your body fat can help to reduce leptin levels, and as leptin resistance can cause increased hunger, it’s generally recommended that to stay fuller for longer, you should eat a diet rich in protein, soluble fibre, and unrefined carbohydrates. These foods all help to reduce your hunger levels, as they keep you fuller for longer. They’re also generally fairly low in calorie content (compared with dairy, fats, and refined carbohydrates), so meals based around these food groups should also ensure a diet that’s low in calories and fat.  

Unfortunately, there’s no overnight way to reduce leptin levels or lose weight, but long-term lifestyle changes can help you over a period of time. In the short term, medications that help to suppress your appetite may help if you find that your hunger is hard to control. 


How does sleep affect leptin and ghrelin? 

Leptin and ghrelin levels are known to be affected by sleep, as studies have shown that if you don’t get enough sleep (or good quality sleep), your ghrelin levels are more likely to increase and your leptin levels are more likely to decrease. Because of this (and many other reasons!) we recommend that you make sure to get a good rest every night. This may mean going to bed earlier or getting up later in the morning, and making sure that you practice a good night-time routine, such as avoiding electronics for a while before bed, making sure not to eat too close to bedtime, and practicing relaxation.  

Sleep deprivation can cause and contribute to many health issues, so it’s always important that you get a good night’s sleep. If you find that you’re still struggling to sleep or that you’re feeling tired during the day, you should visit your GP, as you may have an underlying condition which is causing fatigue or insomnia. Many people with excess weight experience sleep apnoea, which can cause you to stop breathing during the night, and result in a poor quality of sleep and daytime fatigue.  



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