The Anatomy of Hunger

When trying to lose weight, it’s important to understand the anatomy of hunger. Knowing how our bodies help us determine true physiologic hunger for food and nutrients helps us to understand how we can work with our bodies to achieve our health goals.

Our hunger is determined by a complex system of hormones that inform our brains when we are hungry and when we are full. These hormones are released both in response to the food we consume as well as in response to how much fat is stored in our bodies. However, hunger hormones are also affected by things such as the types of food we eat and whether we are fasting or restricting our intake.

Hormone Types and How Our Brains Interpret Them

Your stomach releases a hormone called ghrelin, which signals hunger to the brain. Ghrelin levels have a predictable rise and fall in relation to mealtime and nutrient intake. When we haven’t eaten, our ghrelin levels will rise, signaling to the brain that we are hungry, and once we consume food the ghrelin levels will fall, signaling that our hunger is no longer there.

Another hormone called GLP-1 is released by the small intestine in response to nutrient intake, but unlike ghrelin, GLP signals fullness to the brain. When we start to eat food, our small intestine sends GLP-1 to the brain to signal that we are full and no longer need to feel hunger. GLP-1 also signals to the pancreas that it needs to produce insulin to help manage the sugar flow in our bloodstream.

There are also hormones which monitor the amount of energy, or fat, already stored in the body. Leptin is a hormone that is released by fat cells to signal that you already have much of the energy you need. The more fat stored in your body, the more leptin will be released, which your brain will interpret as satiety, or fullness.

These hormones respond to food and work together to tell your brain when you need more nutrients or when your body already has what it needs.

How Fasting or Restricting Consumption Affects Your Hormone System

When you are fasting or restricting and do not eat, your hormones get dysregulated. For example, leptin levels will drop, signaling to your brain that you need more energy and creating a greater hunger, regardless of the amount of fat stored in your body. GLP-1 will also drop, further enhancing that hunger. In other words, when you don’t eat for a while, your body feels extra hungry, which usually results in eating more than you should.

Alternatives to Fasting

Instead of fasting, you should focus on eating properly. Your hunger cues respond not only to the fact that you have eaten, but also to what you have eaten. Hunger hormones respond more strongly to protein than to fat and carbohydrates. Therefore, having a higher protein diet will help preserve muscle mass and your metabolism, helping you feel full and satiated. Consuming whole foods, as opposed to processed food, can also help regulate your hunger hormones.

Knowing how your body signals hunger and how it reacts to different types of food can really aid you in your journey to becoming healthy. Keeping these things in mind as you create new habits may help you make smarter, healthier choices and allow you to work with your body, not against it.



My mission is to educate, empower and inspire my patients to achieve health and wellness by drawing on best medical practices and a holistic mind-body approach while integrating my personal value system grounded in empathy, integrity and authenticity

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