Leptin And Leptin Resistance: Everything That You Need to Know

Written by Ahmed Zayed Helmy, MD, on September 16, 2020

Are you struggling to lose weight? And when you finally do, do you notice the loose weight coming back after a while? It may not be your fault, as you have been thinking. In fact, it may as well be something wrong with a very important hormone of yours called leptin. Have you heard about leptin resistance and what it can do to your body? If the answer to that question is no, then you are in luck because today we are sharing everything that you need to know about leptin and leptin resistance.

What is leptin?

Leptin is one of the many essential hormones in our body. You might recognize leptin being referred to as the “satiety hormone” or the “hunger hormone." It is being produced by the fat cells in the body, with the hypothalamus being its primary target area in the brain (1).

The function of leptin is to make sure that your brain is aware that you have enough fat stored in the body because as much as we do not like it, fat and fat cells are important for our wellbeing. When there is enough fat stored in the body, our brain is being informed that we can stop eating and can burn calories at a normal rate.

This is called long-term energy regulation – the main function of leptin in the body. Well that, and also being responsible for the number of calories that we eat and burn on a daily level as well as the fat storage in the body. This is the main body function of leptin. But leptin is also responsible for other body functions as well, such as those related to our immunity, fertility, and brain function (2, 3).

But mainly, leptin keeps us away from overeating and starving, both of which bring many serious health issues that through the leptin system, our bodies efficiently stay away from. However, if anything is broken in the leptin’s mechanism of action, it can have a serious negative impact on our health, leading to either starving or overeating.

Leptin’s mechanism of action explained

We mentioned leptin being produced by the body’s fat cells. From there, it is being released into the bloodstream and carried to the brain, or a specific brain area called the hypothalamus. This is the brain area that is responsible for controlling how much and when you eat.

Now back to the fat cells. They produce leptin to let the brain know how much fat they are carrying, meaning how much fat there is stored in the body. While high levels of leptin point out to high levels of stored fat, low leptin levels inform your brain that there is only a low amount of fat being stored.

When the leptin levels are high, your brain is being informed that it needs to stop eating so that overeating does not occur. On the other hand, when the leptin levels are low, your brain gets the information that it needs food to prevent starvation (4).

When you eat, the body fat levels increase, which leads to your leptin levels to increase as well. At such an event, you eat less and burn more of the stored fat, which would lead to weight loss. However, when you do not eat, the body fat levels understandably decline, causing your leptin levels to decline as well. At that point, you will eat more and burn less of the stored fat, thus increasing the risk of overweight and obesity over time.

What is leptin resistance?

From what we know so far, it is understandable that overweight and obese people have high levels of stored fat in their bodies. Because of their high levels of stored fat, they also have high levels of leptin as well (5).

But these events, under the normal circumstances, should not cause any worry, thinking how because of the high leptin levels, these individuals would simply eat less and that way would be burning through their fat storages. Unfortunately, a lot of the times, within obese people, their leptin signaling is not working, leaving the brain unaware of the high leptin levels in the body.

This is a condition known as leptin resistance in which the brain does not receive the leptin signal, which leads to it thinking that you are starving. In reality, the body has more stored fat that it could ask for; however, because of the leptin resistance, your brain requires you to eat more to prevent starvation and death (6).

Your brain changes its entire behavior trying to preserve your life. It will either encourage eating more, or it will reduce the number of calories that are burned on a daily level. And that is how leptin resistance is one of the biggest biological contributors to obesity (7).

So when we see people that are eating more and being less physically active, we normally recognize that being as the cause for their weight gain. However, their weight gain and their changed behavior and poor lifestyle choices might as well be a consequence of leptin resistance, an underlying hormonal defect that they are unaware of (8).

What causes leptin resistance?

Before we go on telling you what can be done for the existing leptin resistance to be reversed, first, let’s review these two possible mechanisms that might as well be the cause of leptin resistance in your case.

High leptin levels – One of the major causes that we review before is having high leptin levels.
Inflammation – Another common cause of leptin resistance in both animals and humans is inflammation. When we say inflammation, we mean inflammatory signaling in the hypothalamus, which will lead to reduced low leptin signaling (9).
High levels of free fatty acids – Having high free fatty acids levels in the blood can increase the fat metabolites in the brain, thus interfering with the leptin signaling and leading to leptin resistance.

The impact of leptin resistance on weight loss

A lot of the times, now only is leptin resistance the cause for overweight and obesity, but it is also the cause of why so many people struggle to lose weight and, despite their greatest efforts, still fail to do so. Also, leptin resistance can lead to unexplained weight gain as well, so let’s discuss this mechanism of action a bit.

If you are leptin resistant, you will likely experience symptoms such as hunger, increased appetite, slower metabolism, fewer calories being burned, and often even psychological symptoms. You may notice as you feel less motivated to head to the gym and get a good workout, crave junk food and sweets, have mood swings, feel irritability and anxiety, etc. Of course, all of these symptoms will do nothing good for your weight loss (10, 11).

These symptoms, surprisingly enough, develop as a result of the decline in leptin levels. A decline in leptin levels happens when you are losing weight and losing body fat. This means that you will lose a significant amount of body fat even when you are leptin-resistant, but those weight loss results will not be here for a long time. They are all a part of this mechanism in which your brain thinks that you are starving and thus initiates all of these actions to that you would regain the lost body fat.

You might recognize this mechanism as the so-called yo-yo dieting (12). People are losing weight only to regain that lose weight back in a short amount of time, without being unaware of the reason for that. And while there are many possible reasons to be considered, one of the most common is leptin resistance.

Do you struggle with leptin resistance?

If you, too, are wondering whether or not you are a victim of leptin resistance with that being the cause of your unsuccessful weight loss and/or unexplained weight gain, then ask yourself the following questions. If you happen to have a positive answer to more than one question, do discuss with your doctor the possibility of having leptin resistance.

Do you find it difficult to lose weight?
When you lose weight with dieting, do you still have a lot of loose, saggy skin?
Do you have trouble maintaining your weight loss results?
Do you battle constant hunger?
Do you struggle with high-stress levels?
Do you have high blood pressure?
Are your triglycerides levels high?
Do you crave sugary foods and junk food often?
Do you get irritated when you do not eat any sugary foods and junk food?

How to increase leptin sensitivity

And now to the most important part of the article – How to reverse leptin resistance and improve leptin sensitivity to live a happier and healthier life. Note that improving your leptin sensitivity will also help you lose weight and achieve sustainable weight loss results that you will be proud of. In the following, you will find some methods which we encourage you to apply to your everyday life and feel as your leptin sensitivity is finally improving.

Get enough sleep

Getting enough sleep has a positive influence on your entire health, whereas sleep deprivation will only reflect poorly, causing a line of health issues. According to a study published back in 2004, short sleep duration has been linked to not only low leptin levels but also elevated ghrelin levels and increased BMI (13). So if you want to improve your leptin sensitivity, you better be staying away from the TV or your smartphone late at night and hitting the bed earlier tonight!

Be physically active

A 2001 study has demonstrated that long-term lifestyle changes that include regular physical activity and a well-balanced diet have a positive impact on leptin sensitivity (14). So even if you are struggling with low motivation when it comes to working out, make an effort to do it anyway. You will see improvements in no time, that is for sure.

Stay away from processed food

If you remember, we mentioned inflammation being one of the causes of leptin resistance. One way in which you can efficiently reduce any present inflammation is by staying away from any processed food, sugary drinks, candy, and junk food. As much as you may enjoy in and crave them at a time like this, find the will to avoid them and eliminate them from your diet. Instead, replace them with whole foods, fiber, protein, and healthy fats that will keep you full for a long time (15, 16, 17).

Stay hydrated

While drinking the recommended eight glasses per day might not necessarily help directly improve the leptin sensitivity, it will help a lot with the symptoms caused by leptin resistance. For example, drinking two glasses of water before your meal has been scientifically proven to be able to prevent overeating and reduce calorie intake (18). Also, having a glass of water whenever you feel hungry can help you distinguish real hunger from being thirsty or simply board. So we highly recommend sipping on water throughout the day to help boost your metabolism, reduce your calorie intake, and help you feel refreshed and healthy.

Lower your triglycerides levels

Having high triglycerides levels will not do you any good, which is why it is for your benefit to do whatever you can to reduce them. Having high triglycerides levels is mentioned as one of the common causes of leptin resistance, thinking about how it can prevent leptin from being transported from the blood to the brain (19).

The best way to reduce your high triglycerides levels is by reducing your carb intake. One trick that will help with that is eating complex carbs that will require calories to be burn to digest them while keeping you full for a long time and avoiding simple carbs such as sugary drinks, sweets, and energy drinks.

Conclusion

Leptin – a valuable hormone produced by no other than your fat cells only to be later delivered to the brain where it fulfills its main task – informing the brain that you have had enough food, and it is time to put that plate away. However, a lot of things can go wrong, and soon you could be looking into leptin resistance and its impact on your weight, increasing the possibility of becoming either overweight or obese.