"Know Your Hunger Hormones" discussed the role of leptin and ghrelin in appetite and satiation. Here is a quick primer on other important hormones that play a role in appetite:
Amylin, secreted by beta cells in the pancreas, delays gastric emptying and also helps to lower blood sugar levels. This helps with satiation and delaying hunger.
CCK (cholecystokinin), a peptide secreted by cells in the small intestine, can help to suppress hunger and inhibit gastric emptying (so you feel fuller longer).
CRF (corticotropin releasing factor) is secreted in the hypothalamus and helps to drive the body’s stress response. It also appears to reduce appetite.
Dopamine, secreted by the anterior pituitary gland, has been called the feel good hormone. It acts to help intensify pleasurable feelings from eating, but it can also contribute to cravings.
Glucagon, produced in the pancreas, increases feelings of fullness or satiety. It’s the counterbalance to insulin.
GLP-1 (glucagonlike peptide 1), released by the pancreas, slows gastric emptying, promotes insulin release, inhibits glugacon release, and helps to suppress appetite.
NPY (Neuropeptide Y) is mostly secreted by neurons of the sympathetic nervous system and is a feeding stimulant (it increases appetite) and also helps to increase the storage of ingested foods as fat.
OXM (oxyntomodulin), found in the colon, stimulates insulin release after carbohydrates are eaten, slows gastric emptying, suppresses appetite and inhibits ghrelin secretion.
Serotonin, manufactured in the brain and intestines, provides a feeling of calm after one consumes a sugary food (carbohydrates). Decreases in levels of this hormone are linked to carbohydrate cravings.
PP (pancreatic polypeptide) is a peptide produced by cells in the pancreas and helps to slow gastric emptying.
PYY (Pancreatic peptide YY) is produced by the pancreas and helps to slow gastric emptying. It helps to stimulate feelings of fullness and typically peaks 90 minutes after starting a meal.
Studies continue to look at manipulating leptin, ghrelin and some of these other hormones in order to manage or intercept obesity. Dopamine deserves an additional look since it plays a strong role in the reward and pleasure centers of the brain. Remember, many of us overeat because of mood swings, and also because certain foods provide sublime pleasure (think creamy and sugary).
Consistent consumption of these foods can actually blunt the response that someone would normally have to naturally sweet foods like fruits. Highly processed foods perpetuate pleasure-seeking food behaviors, reinforcing the desire for more highly processed foods. That leads to overeating, and overconsumption specifically of high calorie, sugar-laden and fatty foods.
One of the reasons that protein-rich meals have garnered scientific interest is because protein contains amino acids and the amino acids help to provide satiation, reduce cravings, and help to increase dopamine production (dopamine contains amino acids). So a breakfast that contains eggs or egg whites and Greek yogurt might be helpful in controlling appetite and providing satiation and satisfaction. Research also suggests that if your dopamine pathway is abnormal due to a genetic variant, consistently producing lower levels of dopamine, you may be at higher risk of eating disorders and developing obesity.
After leptin was discovered, researchers held high hope that it, or leptin analogues, could be used to treat obesity. To date, there has been little success. In 2006, researchers looked at a possible ghrelin vaccine to treat obesity by blocking appetite. Ghrelin has orexigenic and metabolic effects that do make it a good candidate for obesity drug therapy, if undesired side effects can be managed. Saxenda (liraglutide) is an injectable drug whose action is similar to GLP-1, suppressing appetite. It is the only drug in the current arsenal of medications to treat obesity, based on the action of a brain-gut hormone.
Obesity is a complex disease with many causes and interactions. Regardless of the cause, at its core is a lack of energy balance. That energy imbalance and the risk of developing obesity can be affected by an inactive lifestyle, an environment that offers oversized food portions and highly caloric foods, abnormalities in genes that affect your fat stores and predispose you to weight gain.
Other factors that can contribute to this imbalance include inadequate consumption of protein, gut microbe imbalances, health conditions like an underactive thyroid gland or polycystic ovarian syndrome, certain medications like oral steroids, aging, and lack of adequate sleep, (necessary to keep the fine balance between leptin and ghrelin). What is clear is that a delicate balance between leptin, ghrelin and the myriad other gut-brain hormones must be maintained in order to avoid an elevated risk of developing obesity and to support long-term weight loss.
Tips to help support hormone balance:
Get adequate sleep nightly.
Eat on schedule daily to keep cycling hormones in balance.
Consider having a high protein breakfast, and include protein in every meal and snack.
Eat complex carbohydrates, healthy fats and limit sugar and processed foods.
Know the “ghrelin-supressing” foods which include lean meats, Greek yogurt, eggs, fish, nuts, beans and legumes. Lentils, oats and other resistant-starch based foods also help to suppress ghrelin.
Avoid eating food to manage emotions.
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