Leptin Resistance: Overweight but Constantly Hungry

Leptin resistance means overweight individuals rarely feel full

When a person’s body weight is stable, energy intake is equal to energy expenditure, meaning that the same weight can be maintained over a long period of time. However, the increasing levels of obesity in both adults and children of the developed world, shows that this balance is out of kilter.

In the 1950’s and 1960’s, researchers discovered what is referred to as the human obese gene1. This gene, found in fat tissue, produces a hormone named leptin, also known as the ‘satiety hormone’.

Normal leptin response

Leptin is known to play a role in many different biological processes such as immune and inflammatory responses, wound healing and puberty2. Leptin also helps to regulate energy balance by inhibiting hunger.

In a normal weight person, the leptin hormone knows when the body has enough fat for energy and signals part of the brain, called the hippocampus, to tell you to stop eating or to eat less. This feeling of being full is also known as satiety. A separate hormone, ghrelin, secreted in the lining of the stomach, works to increase hunger if you don’t have enough fat for energy. These two hormones work together to regulate hunger.

The hormones leptin and ghrelin work together to regulate appetite

Leptin resistance

In obese individuals, with a diet high in refined carbohydrates, leptin and ghrelin are disrupted so that the brain does not receive the satiety and hunger signals as it should.

Under normal conditions, the more leptin that is circulating in the blood stream, the less hungry that person is.

In obesity, large numbers of fat cells secrete large amounts of leptin hormone into the circulation. The brain becomes resistant to these high leptin levels and doesn’t hear the leptin signal. As a result, the brain thinks the body is starving and triggers constant feelings of hunger.

Research studies have shown that leptin resistance or a lack of leptin production, can lead to uncontrolled eating that results in weight gain3.

Further scientific studies have also shown that diets high in fructose from an early age, can induce leptin resistance4. Fructose is found in large quantities in food such as high-fructose corn syrup, honey, refined white sugar and agave nectar. Removing fructose from the diet reverses fructose induced leptin resistance4,5.

Most obese individuals have high leptin levels but are leptin resistant6.

Diets high in sugar have been shown to induce leptin resistance

Crash diets

The body adjusts its sensitivity to the leptin hormone signals very slowly after weight loss. So even if you have just lost a lot of weight, your hormone regulation hasn’t caught up, meaning that you might think you are hungry when you are not.

This is one of the reasons why crash diets, preceded and followed by periods of overeating, make it very difficult for people to maintain weight loss.

The way to overcome this is to make lasting lifestyle changes, reducing dietary amounts of refined carbohydrates and sugar, and allowing the body to adjust slowly and start listening to the leptin hormone again.

This is one of the reasons why during the 28 DAYS Clean Eating Challenge, it is advised that you stick to 3 main meals and 2 snacks a day, and that you resist the temptation to eat in between these meal times. You can’t always trust your body to tell you when you are hungry, so the 28 day period gives you time to readjust.


The leptin hormone works in the body to regulate hunger, triggering feelings of satiety and being full when you have eaten enough. In obesity, these hormone levels are disrupted and the brain does not receive the signals to stop eating. It is important to give the body time to adjust after weight loss and the best way to do this is to eat set amounts of food at regular intervals, until your hormone levels have adjusted and you are no longer leptin resistant.


Further reading:

Sugar Science: Should I go on a Sugar Free Diet?

Understanding Carbohydrates

Why a Low Fat Diet May Not be the Answer



  1. http://www.ncbi.nlm.nih.gov/pubmed/7984236
  2. http://onlinelibrary.wiley.com/doi/10.1111/j.1467-789X.2006.00270.x/full#b8
  3. http://www.news-medical.net/health/What-Does-Leptin-Do.aspx
  4. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8326080&fileId=S000711451100033X
  5. http://www.ncbi.nlm.nih.gov/pubmed/15314628
  6. http://onlinelibrary.wiley.com/doi/10.1038/oby.2009.228/pdf


About the author: 

Sonia Nicholas is a Biomedical Scientist and Freelance Clinical Science Writer & Editor. She has been working in the field of clinical science for fifteen years.

Sonia believes that everyone can improve their health by eating a clean diet – a claim that scientific research increasingly supports. Sonia also believes that healthy, clean eating is accessible to all and doesn’t have to be an expensive lifestyle choice.

All of the information on The Green Apple Club website is in line with current, recommended Government guidelines. All of the articles are evidence based and fully scientifically referenced.

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Tags: leptin resistance, leptin and hunger

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