Leptin: How This Fat Burning Hormone Works

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September 20, 2019

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We’ve all heard the term ‘fat-burning’, but how does it really happen in the body? 

Fat cells in the body release a hormone that signals to the brain that there is enough energy stored. This triggers your body to burn energy stored as fat. It also affects your desire to eat. Jump to: 

Leptin works in partnership with another hormone called ‘ghrelin’. Leptin helps you to feel satisfied, while ghrelin increases your desire to eat. If you have healthy eating habits, these systems usually function normally. 

When this balance is disrupted, your ability to eat when you are hungry and stop once you are full may be compromised.  

What is leptin?

Leptin is a hormone with a key role in the body’s energy balance. The level of leptin in your bloodstream is one factor that regulates your appetite, body weight and metabolism. 

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What does leptin do?

Leptin is made by the adipose tissue (fat-storing cells) in your body. Its main role is to regulate fat storage and how many calories you eat and burn.

Leptin released from adipose cells travels to the brain via the bloodstream. It acts on the hypothalamus in the brain, which regulates hormones in your body. (See footnote 1)

The level of leptin in your blood is directly proportional to the number of adipose tissue cells in your body. When your body is in a healthy state, leptin signals the hypothalamus to regulate your appetite so that your weight remains stable. 

Leptin also encourages your body to burn energy to produce heat. This process occurs mostly in the muscles.

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What affects leptin levels?

Leptin levels will naturally fluctuate throughout the day to control your appetite and signal when you should eat. When you’ve just eaten, leptin is released from the fat cells. Your metabolic rate increases and your appetite decreases. 

As time passes since your last meal, leptin levels will drop, your metabolism slows and that’s when you become hungry. 

Yo-yo dieting has a negative impact on natural regulation of leptin. When you follow a very low-energy diet, your leptin levels can decrease, slowing your metabolic rate. 

When you return to normal eating patterns, you may eat more than you need to. This constant back and forth can result in your body becoming less sensitive to leptin. 

Apart from regulating appetite, leptin also plays a role in regulating the thyroid gland, adrenal glands and the production of growth hormone. 

Leptin resistance

Sometimes your body can become unresponsive to leptin in your bloodstream. When this occurs, a medical condition called leptin resistance may be diagnosed. 

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What is leptin resistance?

Leptin resistance is when your body doesn’t respond to changes in the levels of the leptin hormone. Leptin resistance could contribute to an increase in weight gain and storage of energy in adipose cells (See footnote 2)

When the brain is unresponsive to high leptin levels, the body mistakenly experiences hunger, even though there is enough energy stored. Leptin resistance also reduces the metabolic rate to conserve energy. 

As a result of this internal miscommunication, leptin resistance can make losing weight more difficult. 

It’s important to remember that leptin is just one factor in regulating your body weight — overall diet, genetics, age, general health and level activity also play critical roles in body composition. 

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What causes leptin resistance?

The exact cause of leptin resistance hasn’t yet been determined by research, however there are some warning signs that may appear before leptin resistance is diagnosed: 

  • Inflammation: Inflammation in the hypothalamus can cause miscommunication of leptin signals. This may be caused by regularly eating highly processed foods that are high in refined sugar and saturated fat. 

  • Free fatty acids: If there are large amounts of free fatty acids in the bloodstream, these can interfere with leptin signalling. 

  • Pre-existing high leptin levels: When leptin levels in the blood are consistently high, the body develops resistance to leptin. 

  • Cortisol: This stress hormone can make the brain less receptive to leptin. 

Many factors of the modern lifestyle, including stress, lack of exercise, lack of sleep and consumption of highly processed foods, may contribute to leptin resistance. Leptin resistance, in turn, has been linked to obesity. 

So, what can we do to keep our bodies sensitive to leptin and maintain a healthy weight?

Can leptin resistance be reversed?

While research into ways to reverse leptin resistance continue, there is one thing that is clear. Following a healthy lifestyle overall can be an effective strategy for maintaining leptin sensitivity. 

Here are some strategies that have been shown to have a positive impact on leptin regulation: 

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Get enough exercise

Exercise increases leptin sensitivity. You should aim for 30 minutes each day, including both aerobic and strength-building exercises. 

Once you have established a base level of fitness, incorporating high-intensity interval training (HIIT) into your routine once a week can help to stimulate human growth hormone production and regulate leptin levels. 

Following an exercise program designed by a personal trainer can help you find the optimal balance of exercise and rest to manage stress placed on the body

Exercise can help to build lean muscle mass and improve metabolism. It can also protect from leptin disruption, even in people with a genetic predisposition to weight gain.    

Energy that would otherwise be stored in adipose tissue is diverted through exercise to help grow and repair lean muscle. When you exercise, levels of growth hormone, adrenaline and testosterone increase, enabling stored fat to be used as energy. 

Regular exercise also reduces the amount of free fatty acids in the bloodstream that can contribute to leptin resistance. Even when exercise doesn’t result in weight loss, it is still extremely beneficial for hormonal balance. 

Another benefit of making time to work out is the release of endorphins, which helps to counter stress, another factor associated with leptin resistance.

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Prioritise sleep and relaxation

When your body is under stress, it releases the hormone cortisol into the bloodstream. This hormone can have many negative consequences for the body if the levels remain high for a prolonged period of time. 

Chronic stress can lead to overeating or comfort eating. When you are stressed, your body might crave high-energy and high-sugar foods, even if you aren’t hungry. This is an evolutionary response that once allowed you to have instant energy to run from perceived danger. 

To reduce stress and allow your body to find a healthy balance, make time for sleep and relaxation. Scheduling time for mindfulness or meditation, yoga, stretching and spending time with friends and family can also help to reduce stress and lower cortisol levels. 

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Eat foods with plenty of fibre

High-fibre foods usually contain the best nutritional value, as well as providing a feeling of fullness and satisfaction. Examples include fruit, vegetables, legumes and whole grains. 

These foods fill you up because they are high in volume, water and fibre while providing fewer calories, so they can help to prevent overeating and reset the leptin cycle. 

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Reduce processed foods

Highly processed foods can interfere with the hormonal regulation of appetite. This includes foods high in refined grains, added sugars, added fats, artificial flavours or sweeteners and other artificial ingredients. 

Some examples of foods to avoid include soda and sweetened beverages, white bread, candy, french fries and processed meats.

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Eat more protein and healthy fats

Eating protein helps to control hunger and maintain lean muscle mass. Healthy fats are more energy-dense but are essential for the absorption of nutrients. Healthy fats make meals more satisfying and keep you feeling fuller for longer.  

What is the leptin diet and how does it work?

Satisfying, nutritious foods that make you feel full are considered best for improving leptin sensitivity. 

There are two aspects to food that makes it satisfying. The first is palatability — whether food tastes good and has an enjoyable or interesting texture. The second is reward — the pleasure and momentary value that food provides whilst you are eating. 

These two factors play a role in the neural pathways in the brain that control leptin and eating behaviour. 

The leptin diet aims to maximise the flavour and nutrition you get from food and includes foods that are high in Omega-3s like nuts, seeds, beans and cold-water fish. 

The leptin diet was designed by a certified nutritionist and incorporates many of the principles of weight management. It places emphasis on portion control, avoiding synthetic additives and reducing refined carbohydrates. It’s accompanied by easy to maintain exercise guidelines.

The leptin diet guidelines include: 

  • Eat 20-30 grams of protein at breakfast.

  • Have three meals per day with no snacking between meals.

  • Reduce, but don’t eliminate, carbohydrate intake.

  • The overnight gap between dinner and breakfast should always be 12 hours. It’s recommended that you finish eating at least three hours before sleep. 

  • Practice portion control and stop eating before you feel completely full. 

As with any diet plan, you should consult with your GP or health professional before making changes to your eating style. 

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A healthy, balanced lifestyle can help to regulate leptin levels

While leptin is a critical component in managing the energy stores in the body, it’s just one factor in a whole cascade of factors that influence your appetite and how energy is stored in the body. 

You can reduce the likelihood of leptin imbalance by implementing healthy habits into your life. These may include eating a wide range of healthy foods, getting regular exercise and surrounding yourself with a supportive community.  

1 Li, Min-Dian. “Leptin and beyond: an odyssey to the central control of body weight.” The Yale journal of biology and medicine vol. 84,1 (2011): 1-7. (Accessed 20 Sept 2019)

2 Klok, M. D., Jakobsdottir, S. and Drent, M. L. (2007), The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obesity Reviews, 8: 21-34. doi:10.1111 /j.1467-789X.2006.00270.x (Accessed 20 Sept 2019) 

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* Disclaimer: This blog post is not intended to replace the advice of a medical professional. The above information should not be used to diagnose, treat, or prevent any disease or medical condition. Please consult your doctor before making any changes to your diet, sleep methods, daily activity, or fitness routine. Sweat assumes no responsibility for any personal injury or damage sustained by any recommendations, opinions, or advice given in this article.


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