The Role of Appetite in Weight Loss

Have you ever wondered what makes you hungry? What causes cravings? Whether or not, as my mother-in-law insists, you truly do have a second stomach organ just for dessert?

What if we ate when we were hungry, stopped eating when we were satisfied, and repeated that process day in and day out? Nutrition reduced to subsistence would make weight management much simpler than it is. The reality is, that a variety of biochemicals send signals between the brain and the body to control both hunger and appetite, and the difference between the two is complex.

Losing weight is simple but not easy. Manipulating weight is a matter of calories in and calories out. However, our actions are driven by a complex slurry of chemicals that regulate our food desire and intake. 

Understanding the function and role of our appetite in weight loss may make the process just a bit easier.

What Is Appetite?

While hunger is the physical need for food, your appetite is the desire for food. It can be challenging to distinguish the difference between the two, but understanding them independently is important.

You can have the desire to eat but not need to eat (this is where that dessert stomach comes into play after a large meal), and you need to eat and have no desire to eat (think about when you may be stressed or busy).

While it seems like your stomach should be calling the shots for your eating patterns, it is actually controlled by the appetite which is a complicated interaction of hormonal signals that originate from fat cells, cells of the pancreas, and cells in your digestive organs. These signals are also processed through cognitive and emotional filters in the brain.

Related Blog Post: How Does Weight Loss Work?

What Controls Appetite?

Appetite is governed by two systems of the body: the endocrine system and the nervous system. Together, these systems actually have one of those celebrity-couple name mashups and are known as the “neuroendocrine system.”

The Endocrine System and Appetite

The endocrine system is your hormone system. It is made up of a series of glands that produce and secrete the hormones your body needs for a wide variety of functions. In addition to all the major endocrine glands, some of our organs also play a role in our hormonal activity. These include the brain, stomach, and intestines.

The job of these endocrine organs is to react to changes in the body and send signals to the body (aka hormones) about how to appropriately respond. These hormonal messages from the organs to the brain are what essentially create the appetite. Some of the hormones involved in regulating your appetite include:

Grehlin- Released in response to low food intake or periods of fasting and stimulates the release of growth hormone to encourage eating.

Leptin- Released with low calorie intake and low body fat levels by the fat cells. Leptin regulates long-term energy balance by suppressing food intake.

Ghrelin- Released in response to low food intake or periods of fasting and stimulates the release of growth hormone to encourage eating.

Gastrin- Released when foods enter the stomach (especailly protein dense foods) and initiates the digestion process.

Amylin- Released after meals to partner with insulin. Amylin slows the emptying of the stomach and suppresses blood sugar spikes.

These hormones, among many others, work together to increase or decrease your appetite in order to regulate food intake and maintain energy balance.

The Nervous System and Appetite

While some appetite control starts with nerve and hormone connections between the digestive system and the brain, the digestive system actually posseses its own, localized nervous system, called the enteric nervous system.

Nerve impulses and neurotransmitters direct nervous tissues, smooth muscles, and certain organs of the body to move and mix food in the digestive system. This “brain” in your gut can relay, amplify, and accentuate different signals between cells of the body. Some of the neurotransmitters involved with appetite regulation include:

Norepinephrine- Decreases digestive activity in response to stress for fight or flight situations.

Acetylcholine- Opposite to norepinephrine, stimulates digestive activity. It also stimulates other digestive hormones, increases intestinal secretions, and dilates blood vessels.

Neuropeptide Y (NPY)- Released when body fat is low or food is seemingly scarce, NPY slows gastric emptying and transit time to increase nutrient absorption.

Serotonin- Released after meals, serotonin is linked to regulating anger, aggression, temperature, mood, sleep, appetite, and vomiting.

These neurotransmitters, among many others, work together with your hormones to increase or decrease your appetite in order to regulate food intake and maintain energy balance.

What Influences Appetite?

People are driven to eat for many reasons beyond physical hunger. Social cues, such as large meals with friends can increase food intake. Cultural norms, such as cleaning your plate or sensory cues such as the smell of freshly baked bread can influence appetite and change the amount of food we eat.

Sleep- Sleep habits can influence the hormones that control appetite. Grehlin increases with poor sleep and produces greater feelings of hunger. Leptin also decreases with poor sleep which will require more food for a person to feel satiated at a meal.

Stress- Stress, anxiety, depression, and grief can reduce appetite because of the changing levels of norepinephrine in their system. Conversely, stress can also increase appetite through emotional eating or the process of using the mood-boosting effects of food as a coping mechanism to manage their stress.

Illness- Illness can strip people of the desire to eat, because immune cells relase proteins called cytokines that suppress appetite to encourage more rest. This is the body’s way of using all its resources to fight off the infection, and energy balance takes a temporary back seat to that.

Exercise- Physical activity can moderate levels of leptin, ghrelin, and insulin and plays an important role in appetite regulation. In addition to physical activity, those who regularly exercise become more efficient at using body fat as a fuel source, and this can help to regulate appetite by preventing blood sugar fluctuations.

Calories Burned Sitting vs Standing: The NEAT Way To Be More Physically Active

Conclusion

Eating a reasonable amount of food to support health and performance goes beyond willpower. Your appetite plays a big role in influencing what and how much you eat and it is important to acknowledge that appetite is more than a feeling. Your appetite is a physiological response to the many messages being transmitted throughout your body.

Acknowledging the information our body relays about hunger and fullness can be helpful in regulating appetite. However these appetite cues can be altered with excessive or chronic stress, poor sleep hygiene, changes in body weight, and lack of physical activity.

---

Gallery Block

This is an example. To display your Instagram posts, double-click here to add an account or select an existing connected account. Learn more