Hunger Hormones: Leptin & Ghrelin

Ahh, hunger. A feeling we’re all affected by, some more than others (hangry, much?). 

We need to eat to survive, of course, but what we eat has such a huge impact not only on our overall health, but on our progress in the gym. None of this is news. But what you might not know is what’s happening in your body when you feel that pang of hunger or that food envy feeling we all get when we walk past the alluring smell of a bakery. Obviously hunger is a physical manifestation, but you might be surprised at how much the mind plays a part in it as well. The feeling of hunger is largely controlled by hormones and neurotransmitters. Meaning, a huge part of the sensation is totally in your head! A few things influence those brain chemicals; the energy we have available, stress and reward-driven factors all come into play when we start to feel hungry. It’s surprising how much our environment can influence how much we eat. Boredom is a huge influence; how many times have you eaten out of sheer boredom? Or gone out with friends who are overindulging? It takes serious will power to stick to your food plan when all your friends are mowing down on pizza and beer. You’re not alone! 



Hunger suppressants have been a weight loss tool for decades, and there is no shortage of drugs and supplements you can take to curb your hunger. But wouldn’t you rather control it naturally without weird pills or deprived, unsustainable diets? Fact is; you can. All you need to do is understand how hunger works in the body and figure out how to manipulate it to your benefit. 

It all begins in the stomach. When its empty and starts to growl for sustenance, a hormone called ghrelin is released from the GI tract. Ghrelin is commonly known as the hunger hormone, and plays a huge part in how the body acts when its hungry. The release of ghrelin stimulates the appetite and releases brain transmitters that increase the sensation of hunger. It’s important to note as well, that ghrelin affects the limbic system, the reward center of the brain, and can sometimes be released to trigger “food memories”, which can cause cravings for pleasurable foods. So, while yes, it does help us out by telling the brain when we actually do need food, it can also work against us to trigger those high-fat, high-carb food cravings. So, this nifty little hormone can be blamed for both homeostatic (physical) and hedonistic (emotional) feelings of hunger. Basically, ghrelin cannot be trusted! 

Interestingly, some studies have shown that obese people may lack receptors in the limbic system that process the response to the ghrelin hormone. This can cause people to eat more and more, as the receptors aren’t signalling to the brain to let it know the stomach is full. Stimulating the receptors in the limbic system not only tell the brain that the stomach is full, but they also give off “feel good” hormones like serotonin. If the receptors aren’t working properly, the danger is that people will keep eating and eating, not feeling full, with the goal of reaching that “feel good” feeling that might never come.  


Insulin plays a big part in hunger as well. Check out our full article on insulin sensitivity here for more information on insulin, but in the meantime we’ll give a quick rundown on how it works with regards to hunger. Insulin’s main function is to regulate the body’s blood sugar. When we eat foods high in sugar and refined carbs, blood sugar will increase and insulin will be released to try to balance it out. When insulin is elevated in response in to high blood sugar, hunger will be decreased. If insulin production is high and blood sugar is low, hunger will skyrocket. The latter shouldn’t happen in healthy individuals, the pancreas produces insulin to regulate blood sugar, so it shouldn’t ever be high when blood sugar is low, but it can happen, especially in people with an insulin resistance like diabetics.  

So if insulin is the regulatory body and ghrelin is the enemy, leptin is the ally. The hormone leptin gets released from fat tissues and travels to the brain and binds with receptors to decrease hunger and stimulate the metabolism. Leptin is the hormone you can thank for naturally suppressing your appetite and is key for overall hormonal balance. When we eat, leptin levels go up, telling the brain to signal that the stomach is full. It acts as a safety mechanism of sorts to regulate energy expenditure as well as food intake. It is our friend! However, some chronic habits can endanger leptin’s noble cause. Eating a lot at night, binge eating and chronic yo-yo dieting can cause the brain to become resistant to leptin’s message to reduce hunger. This can happen when you cut calories and lose a bunch of weight; in this case, leptin levels will decrease and the brain will send signals to eat more and burn less. This could be an evolutionary trait; it could be attributed to the old days when stress often meant a scarcity of food. When the body isn’t eating enough and losing weight, it’s protection method will be to signal to the brain that it’s time to search for food. Nowadays, especially in this lovely first world of ours, that is not going to be the case, so it’s almost like the boy who cried wolf. If fooled too many times, the brain will figure it out and stop doing what it’s told. So to summarize leptin; when you gain weight, fat cells increase, as do leptin levels. This can lead to leptin resistance, which leads to disrupted signals leading to overeating, increase in calories and ultimately, weight gain. Resistance to leptin is one of the most common causes of obesity. Some of the key tips to avoid getting to a leptin resistant (or insulin resistant) stage are the common ones: eat less junk and more fruits, vegetables, complex carbs and proteins. Exercise regularly. Get good quality sleep; check out our sleep optimization article here for some tips on how to do that. 

Another thing worth mentioning is to beware of chronic yo-yo dieting. If you’re constantly dieting and switching between the fad diets du jour, your body will only get confused and ghrelin levels will increase, causing you to feel hungrier (hangrier?) more often than not. There’s nothing wrong with food planning and nutritional strategising. A common way to avoid the ghrelin explosion that comes from yo-yo dieting is to start practicing calorie cycling. A good rule of thumb is to have a 4-6 week dieting phase followed by a 1-2 week caloric maintenance phase. Not only is it easier to focus and stick to it when it’s broken into smaller segments, the ghrelin monster will be less likely to rear its ugly head. 

Be patient with the process. Weight loss, gains and lifestyle changes don’t happen overnight and you’ll be much more successful if you plan in advance and have clear goals in mind. It’s the usual suspects, really! A healthy diet, regular exercise, good night sleeps and a life as free from stress as possible are the keys to controlling your life, and your hunger.  

Ashley Jude

IG @ashleyjude




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