The Science of Hunger & Cravings

The following is a relationship between our appetite and eating behaviors:

• Gut-brain hunger signals (when your stomach tells your brain when you’re full or hungry)

• The brain reward process (feeling pleasure or joy from food)

• Cognitive control processes (conscious thoughts, feelings, decisions, mindset, and control over behavior)

What is Hunger?

Hunger is a psychological experience or a feeling between our gut and brain. There are receptors throughout our digestive tract which detect the presence of nutrients. When there are not enough nutrients in our digestive system, hunger hormones are produced which send a signal to the hypothalamus, the part of the brain that controls hunger and thirst. This then increases our appetite and makes us want to eat.

The same is true for what happens during a meal. When we eat, nutrients in the gastrointestinal (GI) tract produce hormones that communicate with the hypothalamus. They tell the hypothalamus to produce:

• Neuropeptides are molecules that influence the activity of the brain and body.

• Cocaine and Amphetamine-Regulated Transcripts (CART), are proteins that suppress hunger. CART affects our sense of reward, stress, and eating behaviors.

During a meal, hormones also produce signals when we start to experience fullness while eating. Other times, hormones are produced after the meal when we experience fullness and don’t feel any more desire to eat.

Short-term Hunger

In response to food or a lack of food, the body also creates short-term hunger signals. These short-term signals are controlled by longer-term signals from the neuroendocrine system which makes and releases hormones. Examples of longer-term signals include insulin (secreted by the pancreas) and leptin (secreted by fat stores in the body). These longer-term signals control how responsive the brain is to short-term signals.

However, when we gain weight, our brains become less sensitive to leptin and insulin. This reduces the impact of fullness hormones and causes us to feel hunger.

It is important to note that this complex hunger system varies among everyone because of our makeup and biology. It’s also only one of many factors that affect appetite. However, this is one system where people affected by obesity may be more biologically likely to struggle with overeating.

Food is Rewarding

The physiological explanation of hunger outlined in this article doesn’t consider other factors that affect eating behavior. They include psychological factors such as the enjoyment and pleasure of eating. So, while our bodies have an impressive gut-brain system that affects hunger, these signals alone are unable to prevent weight gain in our modern environment.

Palate and pleasure are the most powerful motivators of our drive to eat. The rewarding nature of food can easily overtake fullness signals and make it harder to resist temptation.

Food is essential to our survival. Because of this, we have created a system that constantly puts us around food sources, making us want food and often encouraging us to overeat.

For example, let’s look at two key parts of our brain’s food reward system:

• The endocannabinoid system – A system of signaling molecules whose main function is to help the body maintain homeostasis or a stable internal state. This system affects mood, appetite, stress, sleep, and more.

• The opioid system – A system in our brain that controls pain, reward, and addicting behaviors.

Food Cravings

Food cravings are caused by low blood sugar levels, stress, genetics, and many other factors. Individual food preferences are often linked to what type of foods they grew up with and our cultures. Dieting is hard and understanding the science behind food cravings is important to help you succeed with a diet.

It is a hunger or desire to eat ice cream, chocolate, cake, potato chips, salsa with tortilla chips, hamburgers, shakes, and fries. Often this craving leads to eating too much food with high calories, fat, sugar, and salt. Controlling food cravings helps us to lose and maintain weight loss.

Emotions & Your Food Cravings

Stressful emotions like anger, grief, and fear will give you food craving for sweet food and salty snacks. Food helps with depression and stress this is why people with chronic depression tend to binge on junk foods. This explains why dieting is hard because it is stressful and brings up powerful emotions. Often we crave junk food when dieting because of the emotions and stress that it brings.

According to David A. Kessler, MD.

 "Often people addicted to food think about it more than others. They do not feel satisfied when eating. They react more strongly than others to the smell of food due to the region of the brain that stays activated."

Types of Hunger

Homeostatic Hunger

Women are more likely to have food cravings than men and not have the ability to resist them. This is because the parts of the brain linked to food cravings are not as strong in men. When the stomach is grumbling it is your need for food and calories that is driving the cravings. This is called homeostatic hunger.

This type of hunger is driven by signals from the body and brain. It tells us that we need to eat to fuel our bodies. It tells us when the energy sources in the body are running low. The best way to get rid of this type of hunger is to eat healthy foods that satisfy the appetite. A diet with lean protein, fiber, fruits, vegetables, and whole grains helps with this hunger. Eating a satisfying amount of protein helps satisfy the appetite.  Protein foods are lean meats, poultry, fish, beans, cheese, and dairy products.

Hedonistic Hunger

The second type of hunger is called hedonistic hunger. It is a craving for highly tasty foods. These cravings were developed many years ago. The problem is that with many people it is out of control. The more we eat sweet sugary foods the more the body craves them. It has more to do with pleasure than satisfying your hunger.

This type of hunger is harder to fight as most of the treats we desire have sugar. Ways to deal with this is not to buy large quantities of sweets and clear out your house and pantry. Another way is to eat something foods like a fruit salad, a small portion of pudding, or granola. When you eat treats keep them in small portion-controlled sizes. This helps too.

Conclusion

Overall the science of hunger involves controlling hunger by reducing stress through exercise, adequate sleep, and a healthy diet. Talking with your doctor and asking why I have food cravings is a start. He can often recommend a healthy diet, supplements, and exercise that will help you lose weight sensibly.  This is a way to control cravings and lose weight the right way.