Turn On Your Fat-Burning Switch with Ghrelin & Leptin

September 26, 2017
Ghrelin and leptin - Dr. Axe

According to endocrinologists from the VU University Medical Center in Amsterdam, two of the most important hormones to focus on for natural weight loss and energy balance are ghrelin and leptin. (01) Many experts call ghrelin and leptin the “hunger hormones” because they work to either increase or decrease our appetite. (02)

Although certain weight loss programs involving taking artificial hormones— such as those that use Human chorionic gonadotropin (HCG) to increase fat-burning— can be dangerous, there are safe and effective steps we can take to manipulate our natural hunger hormones and help us reach our weight-loss goals.

It might feel like the cards are stacked against you when it comes achieving sustainable weight loss, but it’s important to understand that we have a great deal of control over our hormones, as they reliably respond to dietary, exercise, and stress-related changes we make. We don’t need to resort to unnatural, harmful methods to lose weight fast and reach our ideal weight— instead we need to focus on setting up a healthy food environment that encourages nutrient-dense eating, managing stress, moving our bodies consistently, and making smart food choices long-term.


What Is Ghrelin?

Ghrelin is an appetite-increasing hormone, given its name because it is considered to be a “growth hormone-releasing peptide” (or GHR). Since ghrelin makes you feel hungry it makes sense that levels tend to rise before meals and fall after meals. How is ghrelin secreted? It’s made in the stomach and fluctuates throughout the day depending on your intake of food. As a s a peptide hormone it is produced by ghrelinergic cells located in the gastrointestinal tract, which communicate with the central nervous system, especially the brain.

Once produced in the stomach, rising levels of ghrelin sends a signal to the brain that causes you to feel hungrier. Regarded as the only appetite-stimulating hormone in humans, ghrelin is one of the main contributors in giving people the “munchies” and potentially causing them to overeat.

What is ghrelin’s effect on growth hormone and metabolism?

Ghrelin and related growth hormone secretagogues increase body weight and fat mass. One way they do this is by triggering receptors in a part of the brain called the arcuate nucleus, which controls leptin and insulin sensitivity. Ghrelin can sometimes override signals sent from the GI tract to the brain that tells you to stop eating, such as those caused by gastric distension (pressure placed on the stomach as it expands). Ghrelin also seems capable of contributing to cellular changes, including alterations in endothelial cells lining the blood vessels. (03)

According to research published in the journal Addiction Biology, ghrelin reduces fat utilization and is a vital component of the food reward cascade controlled by the brain’s pleasure-reward system. (04) Ghrelin levels are negatively correlated with weight, so dieting (especially severe calorie restriction) tends to increase ghrelin output. Ghrelin has been found to play a major role in inducing short-term feeding and long-term weight gain, but the hormone also has other roles, including influencing: (05)

  • Regulation of growth hormone and insulin secretion
  • Glucose and lipid metabolism
  • Gastrointestinal motility
  • Blood pressure and heart rate
  • And neurogenesis (the process in which neurons are generated from neural stem cells)

In addition, more ghrelin is released directly in response to stressful situations, explaining why so many people have the tendency to eat when they’re stressed. By perpetuating the stress cycle, ghrelin contributes to weight gain by maintaining a person’s stress levels and causing strong urges to snack or overeat.

What is the difference between leptin and ghrelin?

Ghrelin and leptin work together to facilitate feeding, energy balance and weight management. Leptin is a hormone that is made by fat cells that decreases your appetite. It essentially does the opposite of ghrelin, which increases appetite. Both hormones play a role in body weight maintenance. Within the brain the same area that holds the receptors for ghrelin (called the ghrelin/growth hormone secretagogue receptors, or GHS-Rs) also holds the receptors for leptin.

Because the body produces leptin based on body fat percentage, weight gain causes your blood leptin levels to increase. The opposite is also true: weight loss will result in decreased levels of leptin (and often more hunger). Unfortunately, overweight and obese people are generally believed to be “leptin-resistant,” which contributes to further weight gain and difficulty losing excess weight because they require more food to feel “full” or satiated. However there is still a lot to learn about how leptin-resistence and increased ghrelin may contribute to obesity. (06)

 

To summarize ghrelin’s main roles, here are three points to remember:

  1. Ghrelin is a fast-acting hormone that plays a vital role in increasing appetite, meal initiation, and contributing to weight gain.
  2. Ghrelin works with another hormone called leptin to manage body weight. Leptin usually mediates long-term regulation of energy balance because it suppresses appetite and food intake, thereby inducing weight loss (although not in the case of obesity).
  3. Both hormones can be controlled naturally, primarily through making smart dietary choices, exercising, sleeping enough and stress management.
Ghrelin and leptin - Dr. Axe

 


How to Make Ghrelin, Your Hunger Hormone, Work for You

How can you lower your ghrelin levels? Here are five steps to take in order to reduce ghrelin and gain control of your appetite:

1. Don’t Overly-Restrict Calories (AKA Attempting “Crash Diets”)

Levels of ghrelin will increase if you’re consistently under-eating, which is one reason why dieting makes most people feel pretty hungry. On the other hand, over-eating causes ghrelin levels to decrease, but this shouldn’t be the goal either (unless you’re trying to gain weight).

The fact that being in calorie-deficit makes you feel hungrier is one ofthe most challenging things about attempting to diet for weight loss. Fortunately however, it’s been found that certain types of dietary habits can help to control ghrelin— including eating lots of nutrient-dense, unprocessed foods and eating enough fiber and protein.

Ghrelin levels should go down significantly following a meal, and stay down for about 3 hours or more before you begin to start feeling hungry again. If you notice yourself getting hungry soon after eating, or frequently wanting to snack throughout the day, consider if you’re eating enough calories in general. It’s possible you can afford to increase your intake of protein, healthy fats, or fiber from complex (unrefined) carbohydrates if you’re severely restricting one of these macronutrients. Eating enough healthy food to sustain your activity level and feel energized will prevent you from entering or staying in “starvation mode” which will increase your appetite.

2. Eat Enough Protein

Even when someone is restricting their calorie intake, eating a higher proportion of protein foods can help control their appetite.

A 2006 study published in the American Journal of Clinical Nutrition that focused on the effects of a high-protein meals on  postprandial ghrelin response states that “The most satiating macronutrient appears to be dietary protein.” When study participants ate a high-protein breakfast they experienced decreased postprandial ghrelin concentrations more strongly over time compared to when they ate a higher-carbohydrate breakfast.

The researchers found evidence that the high-protein meals had an effect on glucose-dependent insulinotropic polypeptides, which mediated the ghrelin response. In addition, the high-protein meals were more effective at slowing gastric emptying, which prolongs feelings of fullness. (07) Other studies point to similar findings about how protein may contribute to weight loss: protein tends to ward off hunger, prevent loss of muscle mass during dieting, increases secretion of satiety hormones, increases the thermic effect of food digestion, and improves glucose homeostasis. (08)

3. Exercise, Especially Burst Training and High Intensity Interval Training (HIIT)

For years, generic weight-loss advice given by most health care providers focused on low-to-moderate aerobic activity, such as walking or running 30–60 minutes every day. Research from the past decade continues to report that ghrelin increases (and therefore appetite goes up) and also that leptin decreases after these types of exercises, making this notion obsolete.’

Instead of doing “steady state cardio”, burst training is one of the best ways to manage hunger and eating behavior, to burn belly fat, and to manipulate ghrelin and leptin to improve the odds of weight loss. Burst training can also increase muscle mass, which means when you do eat more you’re better able to use the extra calories without gaining fat.

In a study conducted by the University of Bath (U.K.), various hormone levels in individuals who participated in burst training (i.e., 30-second sprint on a cycle ergometer controlling for low or high intensity) showed that:

  • Total ghrelin concentrations declined after high-intensity sprinting and were significantly lower after 30 minutes of recovery than they were pre-exercise, suggesting that burst training can not only contribute to weight loss, but help curb appetite long term. (09)
  • Growth hormone (attributed to weight loss) concentrations were greater in the high-intensity than in the low-intensity group, suggesting that burst training affects other hormones in addition to ghrelin. (010)

The Journal of Sports Science recently published similar results regarding burst, high-intensity exercise and blood soluble leptin receptor (sOB-R) concentrations. (011) Findings link low levels of sOB-R to obesity because having less receptors to receive the hormone prevents leptin from attaching to cells, which negates its hunger-curbing and weight-loss effects. After evaluating 18 healthy male volunteers who completed either a low-intensity or high-intensity exercise routine, researchers discovered that:

  • At 24 hours post-exercise, the high-intensity group had significantly higher sOB-R concentrations and significantly lower leptin concentrations than the low-intensity group; this suggests that burst training is more effective at not only increasing the cell’s sensitivity to leptin, but also the overall blood levels of the hormone.
  • Additionally, leptin levels at 48 hours post-exercise were also significantly lower for the high-intensity group, suggesting that burst training, like ghrelin, has long-term effects on weight loss that are beneficial long after your workout.

These are just two examples from a myriad of research studies that prove high-intensity interval training is not only most effective at curbing appetite and controlling weight gain in the short term, but also in the long run.

4. Get Good Sleep (Early to Bed, Early to Rise, So You Can Work Out!)

Getting enough sleep (usually about 7-9 hours per night for mos adults) is associated with better management of ghrelin and leptin. Sleep deprivation was shown in one study involving 12 young men to be associated with an increase in ghrelin levels, appetite, and hunger compared to when the men slept for longer periods (up to 10 hours a night). (012)

To best maximize your exercise routine (especially if your workouts are intense), and best control ghrelin and leptin, research shows that it’s a good idea to exercise first thing every morning if possible. According to a study published in the Journal of Physiology, exercising on an empty stomach may improve glucose tolerance and insulin sensitivity, which are both tied to ghrelin production. (013)

In addition to contributing to type 2 diabetes prevention and weight loss, exercising early in the day is known to help regulate appetite, especially curbing the munchies and the desire to eat unhealthy snacks. One study published in the Asian Journal of Sports Medicine found evidence that “morning exercise may cause greater levels of satiety in comparison with afternoon exercise.” (014)

5.  Practice Stress Management

In addition to making dietary changes and getting enough exercise, it’s important to turn your attention to the level of stress you’re dealing with. The journal Obesity Reviews recently published an article evaluating the effects of combined exercise, sleep and stress management on hormones. Researchers from the study concluded that “Behavioral interventions could offer a practical, cost-effective method for reducing or stabilizing ghrelin levels after initial weight loss to improve weight loss maintenance.” (015)

In other words, the stress cycle must be stopped to first reach your weight-loss goals, and then to effectively maintain a healthy weight over time. Chronic stress is likely to increase your appetite, especially for “comfort foods”, and to contribute to other unhealthy habits like overeating, snacking, not making time to cook at home, possibly drinking more alcohol, skipping sleep and remaining more sedentary.

One suggestion is to wrap up your day on a positive note by practicing Tai Chi or yoga in the evenings, which helps set the tone for a good night’s sleep and also preps your body for your morning workout the following day. There are many ways to help manage stress, but ultimately different techniques will work for different people. Meditation, prayer, writing in a journal, spending time outdoors, sustaining positive relationships, getting enough rest and downtime, and eating an anti-inflammatory diet are some of the best ways to keep your stress levels down and reverse the vicious weight-gain stress cycle.

5. Avoid “Highly Palatable” Processed Foods

Foods that have been refined and processed to taste exceptionally great are usually high in calories and also often low in nutrients. These are called “highly palatable” foods by obesity and nutrition experts (or sometimes “ultra-processed foods and drinks”, or UPFDs), because they tend to cause overeating due to how they activate reward centers in the brain. (016)

Normally when we eat a meal chemical/hormonal messages are sent from our digestive tract to our brain and various other parts of our body to tell us we’ve had enough and to stop eating. But research suggests that when we have the opportunity to eat highly-processed, calorie-dense foods, this feedback system doesn’t work so well. Essentially it seems that the human brain is “hard wired” to seek out and enjoy calorie-dense foods, so including many of them in your diet interferes with appetite regulation.

What types of foods tend to increase appetite and risk for overeating the most? Examples include: (017)

  • Cakes, donuts, cookies, pastries, brownies and other sweets
  • Soda and sweetened beverages
  • Pizza
  • White bread, rolls, wraps, pita, etc.
  • Chocolate, candy and ice cream
  • Salty snacks like chips, pretzels and french fries
  • And fried foods

It’s easy for us to overcome calories and remain “hungry” when we eat foods high in refined grains, added sugar, added fat and synthetic ingredients, especially when these tempting attributes are combined together. Eating a whole-foods diet on the other hand— including one with lots of veggies, fruit, proteins like eggs or fish, healthy fats like avocado or coconut, etc.— is the best way to naturally regulate your appetite since these foods are high in volume, high in fiber, lower in calories, higher in nutrients, and overall more capable of turning down your desire to keep eating.


Precautions Regarding Hunger Hormones & Weight Loss

While I do recommend taking steps to naturally balance levels of ghrelin or leptin, I’d warn against attempting other weight loss programs that involve the use of artificial hormones.

Manipulating hormones in order to boost weight loss is not a new concept. In the 1950s, medical and scientific communities began suggesting artificial hormone therapy to help people lose weight. Topping the list of these weight loss programs is one of the most controversial and hotly debated gimmicks: the use of human chorionic gonadotropin (HCG), a hormone produced during pregnancy that helps release a woman’s fat stores in order to support the growth of her baby.

HCG stimulates the hypothalamus to start fat metabolism, which provides nutrients for the baby. Remove the baby from the equation and those fat-turned-nutrients need somewhere to go. The HCG diet supposedly helps men and women achieve “miraculous” weight loss through a combination of taking HCG and following a diet restricted to just 500–800 calories per day. Basically, this is a starvation diet. The theory behind this misguided use of hormone therapy is that the extra adipose tissue (fat) released in the bloodstream supplements the calories people aren’t consuming each day, helping dieters lose up to two pounds per day. Sadly, ever since Dr. Oz openly changed his mind about HCG and aired a special report on it in 2012, more people are on the diet than ever before.

According to the Mayo Clinic, two important facts are crucial to understanding this type of hormone therapy for weight loss:

  1. The HCG diet is not safe and doesn’t work long term, as most people will regain the initial weight that they lose.
  2. The Food and Drug Administration has actually advised people “to steer clear from over-the-counter weight-loss products that contain HCG.” (018)

Final Thoughts on Ghrelin

  • Ghrelin is an appetite-increasing hormone that makes you feel hungry before meals, but decreased after meals so you feel more satisfied.
  • Ghrelin works with another hormone called leptin to manage hunger, food intake and body weight. Ghrelin increases hunger, while leptin (secreted by fat cells) decreases hunger.
  • Both hormones can be controlled naturally, primarily through making smart dietary choices, exercising, sleeping enough and managing stress.

Read Next: 8 Health Benefits of Eating More Protein Foods


From the sound of it, you might think leaky gut only affects the digestive system, but in reality it can affect more. Because Leaky Gut is so common, and such an enigma, I’m offering a free webinar on all things leaky gut. Click here to learn more about the webinar.

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