Hormones play an integral part in our ability to both shed pounds and feel full. This article covers four hormones, Insulin, Leptin, Ghrelin and Cortisol.

Leptin is the fullness hormone, telling your brain you are full. Obesity has been associated with decreased sensitivity to leptin which makes weight loss more challenging.

Insulin

Insulin is a naturally-occurring protein and hormone found in our bodies that acts to regulate our blood sugar. Composed of two chains joined together with disulfide bridges, insulin plays an integral part in energy homeostasis by regulating carbs and fats and stimulating glucose uptake by muscles, liver and adipose tissue to ensure we have enough energy for daily functions such as muscle movement or fat storage. Insulin also serves as a feedback system which prevents too high a blood sugar from ever occurring – something known as hyperglycemia – by acting as an important regulator.

Starches and sugars consumed through food are broken down into simple sugars by your digestive system and when they enter your bloodstream they send a signal to the pancreas that there is enough glucose available for cell fueling and fat burning. A spike in insulin may occur immediately following eating but normally subsides after several hours before returning back to its regular level allowing fat burning to resume normally.

One popular theory holds that elevated insulin levels — due to eating too many carbs — cause you to feel more hungry, since this hormone signals to your cells that any excess sugar should be stored as fat cells and “emptying out” of your bloodstream and sending it towards fat storage sites in fat cells for storage.

However, this model is likely too simplistic and inaccurate. There are numerous factors which influence hunger and appetite; insulin likely doesn’t play such an outsized role.

Ghrelin, leptin and cholecystokinin are also essential hormones to energy balance and appetite regulation. A change in their delicate balance can have profound ramifications on feelings of satiety and hunger; for example if your levels of ghrelin or leptin drop too low while leptin remains too high, hunger sensations become severe; similarly if cholecystokinin drops below certain thresholds you could feel full quickly after even small amounts of food. Additionally if your thyroid gland overactives the excess hormones could result in hypoglycemia;

Leptin

Leptin is a hormone produced by fat cells. Once released into your bloodstream, Leptin informs your brain that there is enough energy and no hunger signals; additionally it assists your body with turning food into energy for fuel.

Your leptin levels are directly proportional to the amount of fat tissue in your body, creating an effective feedback loop where your appetite diminishes as you lose weight or increases as soon as it returns. In healthy individuals, this system works very effectively to regulate hunger levels and avoid gaining too much weight.

Researchers identified this protein in 1994 when they isolated it from an altered gene of an obese “ob/ob” mice model with insatiable appetites unable to shed their excess pounds. At first glance, researchers thought they could use their discovery as the basis of powerful weight-loss supplements, but the results have proven disappointing.

One theory suggests that individuals with leptin resistance become increasingly less responsive to leptin over time, possibly as their brain is continuously stimulated by high levels of the hormone and stops responding normally to any negative feedback; likely as a protective mechanism against changes in body fat percentage which might indicate threats to survival or reproductive success.

Leptin plays an essential role in several areas beyond appetite regulation, including bone health, fertility and immunity. It influences activity at certain receptors within the hypothalamus, ventromedial nucleus and pulvinar nucleus as well as being involved in inflammation responses that influence both adaptive and innate immunity responses.

Leptin may play a part in leaky gut syndrome, a condition commonly seen among obese individuals and chronic inflammation sufferers. Certain strains of microbes in the digestive tract are thought to contribute to leptin resistance by disrupting stomach lining lining and allowing excess toxins into the body – leading to inflammation, autoimmune diseases, weight gain and poor metabolic profiles – leaving your immune system unable to respond normally and leading to inflammation autoimmune diseases weight gain poor metabolic profile inflammation poor metabolic profile inflammation poor metabolism profile diet rich in fiber good bacteria and plenty of water can help combat leptin resistance and vice versa! A diet rich in fiber good bacteria and plenty of water can help prevent leptin resistance!

Ghrelin

Ghrelin is commonly known as the hunger hormone, but it plays many more functions than just increasing appetite. This multitasking hormone sends signals to certain parts of your brain to increase hunger, stimulates the pituitary gland’s release of growth hormones and plays an integral role in insulin release, protecting cardiovascular health. Furthermore, GHLRIN acts as an energy homeostasis regulator by working alongside leptin to control hunger and food intake as well as regulate adipose tissue storage and glucose metabolism.

Ghrelin is produced primarily in your stomach and increases when your stomach is empty to signal to your brain it’s time for food. Peak levels typically occur before meal times and then decrease once eating has occurred; obesity, diabetes, hypertension, stress sleep disorders or chronic fatigue syndrome may affect this hormone’s levels as well.

Diet, exercise and sleep all play an essential part in managing ghrelin levels and can help lower them. A diet high in proteins such as poultry, fish, eggs, beans or low fat dairy may help suppress ghrelin, so aim to incorporate 25-30% of calories from this source each day. Sleep is also crucial; studies have demonstrated that lack of sleep increases both ghrelin levels and hunger.

Studies have demonstrated that eating foods high in fiber content can reduce ghrelin levels. The effect is most evident when fiber comes from vegetables and whole grains. A high-fiber diet also helps with controlling appetite and maintaining a healthy weight.

Researchers have recently demonstrated that eating a diet high in carbohydrates relative to fat can significantly lower ghrelin levels postprandially. A study that followed participant eating habits and measured postprandial acyl and total ghrelin levels found that diets high in carbohydrates led to significantly lower levels of ghrelin at 3 hours postprandially.

Leptin and ghrelin work in tandem to regulate hunger and food intake, but it’s essential not to let their levels become imbalanced. Eating well, exercising regularly, getting enough restful sleep, and managing stress effectively are all effective ways of keeping these hormones balanced.

Cortisol

Cortisol (glucocorticoid hormone) is produced by your adrenal glands on top of your kidneys and released when you experience stress or danger. Cortisol causes your body to go into fight-or-flight mode, temporarily pausing its normal bodily functions, slowing your metabolism, increasing sugar and fat production for energy sources and temporarily pausing regular bodily functions and metabolism – although necessary for survival, excessive levels can become harmful over time if chronic stress remains an issue.

When your brain detects a threat, such as when you encounter an aggressive dog during your morning stroll, the hypothalamus sends nerve and hormonal signals to both adrenal glands through nerve endings and hormones such as corticotrophin-releasing hormone (CRH) and adrenocorticotropin (ACTH), respectively. These hormones prompting adrenal gland production of and release of cortisol – commonly referred to as stress hormone.

Cortisol increases your heart rate and blood pressure when exposed to higher amounts. Cortisol also raises glucose levels in your bloodstream, helping cells use it as energy and increasing repair materials that repair damaged cells. Furthermore, cortisol helps regulate blood sugar by counterbalancing insulin’s effects to lower it even further if any unutilized glucose remains unspent it becomes stored fat instead.

Cortisol not only plays a crucial role in blood sugar regulation, but may also have an effect on your appetite and weight. Cortisol increases cravings for sweet, fatty and salty foods which can lead to overeating; additionally it makes people hungrier more quickly after meals are finished being consumed.

Researchers conducted the study using salivary cortisol data collected from 348 participants who reported their mood and food cravings throughout the day. Researchers determined that cortisol levels peak early morning and fall off sharply around midnight, providing an accurate measure of hunger and weight changes more effectively than plasma concentrations alone. Unfortunately, due to being cross-sectional it remains unknown whether higher cortisol levels correlate to depressive symptoms or problematic eating behaviors.

Cortisol depletion makes weight loss more challenging; extra sugar in your bloodstream may fuel adipose tissue growth and visceral fat accumulation – leading to insulin-resistant visceral fat that compounds with obesity while contributing to high cortisol levels in turn leading to even more obesity and stress hormone production.