by Donna Hayek RDN
Hormones help regulate appetite by telling us when we are hungry and full. Ghrelin increases to stimulate hunger, while other hormones, such as GLP-1, PYY and CCK, promote fullness. Leptin helps regulate long-term energy balance.
Sleep, stress, diet and exercise can all affect these appetite-regulating signals. Lack of sleep may increase ghrelin and decrease leptin, causing us to feel hungrier. Stress can also increase cravings for high-calorie or ultra-processed foods through its effects on hormones, the brain’s reward system and gut-brain communication.
Appetite hormones may shift when we lose weight, leading to an increase in ghrelin and a decrease in fullness-related hormones such as PYY. These changes can make maintaining weight loss more difficult.
GLP-1 medications mimic the effects of naturally occurring hormones. They help regulate appetite, signal fullness and slow gastric emptying. Depending on the medication, they may be prescribed to help manage type 2 diabetes or chronic weight management. Certain GLP-1 medications may also reduce the risk of cardiovascular or kidney complications in specific patient populations.
A healthy diet rich in fiber can help control hunger by slowing digestion and helping the body feel full sooner and for longer. Fiber also feeds the gut microbiome. Gut bacteria ferment certain types of fiber into short-chain fatty acids, or SCFAs, which may influence hunger, fullness and metabolic health.
Fiber is a type of carbohydrate found in plant foods. It supports regular bowel movements, healthy blood sugar levels and lower LDL cholesterol. Most people should aim to consume approximately 25–35 grams of fiber—including both soluble and insoluble fiber—each day. Individual needs may vary based on age, sex and health needs.
You can monitor your fiber intake by reading nutrition labels or using an app such as MyFitnessPal, Lose It! or Cronometer. Eating slowly can also give your brain time to recognize signals of fullness from your stomach.
Foods high in fiber include vegetables, fruits, whole grains, legumes, nuts and seeds.
Soluble and Insoluble Fiber
There are two main categories of fiber: soluble and insoluble. Many plant foods contain a combination of both.
Soluble Fiber
Soluble fiber dissolves or swells in water. It is found in foods such as oats and other grains, legumes, seeds, nuts, fruits and vegetables.
Soluble fiber absorbs water and forms a thick, gel-like substance that slows digestion. It may also slow the rate at which carbohydrates are absorbed into the bloodstream, helping to reduce blood sugar spikes after eating.
Certain soluble fibers bind to bile acids and help remove them from the body, which can help lower LDL cholesterol. Many soluble fibers can also be fermented by gut bacteria, and some act as prebiotics by feeding beneficial bacteria in the gut. Soluble fiber is not a probiotic because probiotics are live microorganisms.
Insoluble Fiber
Insoluble fiber does not dissolve in water. It is found primarily in whole grains, nuts, beans and many vegetables.
This type of fiber adds bulk to stool and helps food and waste move through the digestive system, supporting regular bowel movements and healthy motility. Insoluble fiber is generally less fermentable than soluble fiber, although this varies depending on the specific type of fiber.
Both soluble and insoluble fiber are important, but individual tolerance can vary, especially for people with gastrointestinal or digestive conditions.