Hunger Hormones
If you're always hungry, read this:
Why am I so HANGRY—the Hormones that Control Us
By L. Jones, RN
There are many hormones that are involved in hunger and satiety. You will find one theme in this article: if you don’t control your hunger hormones, they will control you. Hunger is an extreme feeling that drives us to eat, and I have yet to meet anyone who lost weight and kept it off while they were hungry.
Let's start with the two major hunger hormones: Leptin and Ghrelin.
Ghrelin
Ghrelin can be thought of as the “hunger hormone”. It is primarily produced in the stomach, but also produced by the small intestines, brain, and pancreas. When your stomach is empty, it sends a powerful signal to your brain that it is time to eat. You feel this as a hunger pain. About 20 minutes after your stomach is full, it stops producing ghrelin.
Pro tip: Use this information to your advantage. It takes 20 minutes to feel full. You could shovel down food as fast as possible until you are stuffed. OR… You could eat slowly. Pause throughout your meal. Give ghrelin a chance to start circulating through your body.
Leptin
Leptin is a hormone released by the fat cells. It is the “fullness” hormone. Typically, the more body fat you have, the more leptin your body produces. When leptin levels are high, leptin signals the brain that you are full. When leptin levels are low, your brain is signaled that energy reserves are low, and your appetite increases.
If people with more body fat have more leptin, shouldn’t they get the signal to stop eating? You would think so. If you have a moderate amount of leptin, you will stop eating when you are full. Too much leptin results in leptin resistance–your brain ignores the high leptin levels, it is desensitized to it. Leptin resistance is a vicious cycle. Your brain is ignoring leptin, you are hungry and eat more without feeling satiated, you gain more body fat, and produce more leptin that your brain continues to ignore. Rince, repeat. Often, people in larger bodies do not know what it is like to feel full or satiated. They continue to be genuinely hungry no matter what they eat, unless they re-regulate their hunger hormones.
Insulin Has an Impact on Hunger Hormones Too (Because of Course it Does)
For more information on insulin, please read my article about it! (link here). Insulin is the hormone that allows sugar (glucose) to get into the cells. Often, it is described as the “key” that lets sugar into cells to be used as energy. Insulin is released after eating a meal, and blood glucose is sequestered into the cells.
This leads to lower blood glucose, which triggers an increase in hunger. Insulin can also directly increase appetite and increase the perception of sweet-tasting foods. This is why The Reversal Project tents do avoid snacking–more snacking, more insulin spikes, more hunger, more eating. Three meals are enough.
Insulin resistance is when cells begin to ignore some of the insulin, and insulin resistance is involved in many of our chronic diseases, such as heart disease, type II diabetes, weight gain, and metabolic syndrome. Since less glucose is entering the cells, glucose begins to build up in the blood, resulting in high blood glucose. When cells become insulin resistant, they can feel “starved,” as less glucose is coming in than expected. This can stimulate hunger.
Those are the Big Three. There are a Few Others
Cholecystokinin
Cholecystokinin is mostly produced in the small intestine in response to eating a meal, and more cholecystokinin is produced when you eat a high-fat meal. Cholecystokinin stimulates the pancreas to produce digestive enzymes, which help you break down food in the small intestine. It also stimulates the gallbladder to release bile, which emulsifies fats in your GI tract so that they can be absorbed.
Cholecystokinin also delays gastric emptying, which makes you feel full for longer, and suppresses hunger. Studies indicate that increased amounts of cholecystokinin are associated with decreased appetite
Peptide YY
Peptide YY is a hormone released primarily by the colon, particularly after meals high in fat and carbohydrates. Peptide YY levels in the blood are lowest when you wake up in the morning (before breakfast), they peak two hours after a meal, and then gradually decrease. Low Peptide YY levels are associated with higher body weights. Peptide YY slows digestion, and sends satiety signals to the brain.
Pancreatic Polypeptide
Pancreatic polypeptide is produced primarily in the pancreas. When fasting, levels of pancreatic polypeptide are low. Levels of Pancreatic polypeptide increase in proportion to the number of calories in the meal; The higher the calories, the more pancreatic polypeptide is produced. Pancreatic polypeptide slows digestion and decreases hunger.
Incretins
Incretins are gastrointestinal hormones that signal the pancreas to produce insulin following a meal.
Glucagon-Like Peptide-1
Does this one sound familiar? It probably should. GLP-1 agonists, such as ozempic and zepbound, are the new weight loss drug, and the whole world is buzzing about it. The way these drugs work is by simulating Glucagon-like peptide-1 in the body. Glucagon-like peptide 1 is released primarily by the small intestine after a meal, and it slows down gastric emptying (making you feel full longer) and stimulates the pancreas to produce insulin (making it a useful treatment for type II diabetes). High fat meals cause more Glucagon-like peptide-1 to be released.
Glucose-Dependent Insulinotropic Polypeptid
Glucose-dependent insulinotropic polypeptide is primarily secreted by the small intestine in response to a high-carbohydrate meal. It stimulates the pancreas to produce insulin.
Glucose-dependent insulinotropic polypeptide has a role in fat metabolism; it can increase fat accumulation and fat cell growth, making it implicated in weight gain.
Oxyntomodulin
Oxyntomodulin is produced in the small intestine and colon. It is released in response to food intake and stimulates the pancreas to produce insulin. It has been found to increase energy expenditure and reduce appetite.
Oxyntomodulin also suppresses the production of ghrelin, the hormone that stimulates hunger. This hormone is currently being investigated as a potential treatment for weight gain and type II diabetes.
Much of weight loss research has found that, as we lose weight, our hormones that induce hunger increase, while our hormones that suppress appetite decrease. This leads to ever increasing hunger, and is often followed by binge eating and weight regain. Often these hormones are so powerful, you regain all the weight lost, and then some. Your body is fighting against your weight loss. In weight loss, hunger hormones cannot be ignored. They are driving your eating patterns.