Still Hungry Even Though You Are Physically Full?

Do you ever have the feeling that you are hungry all of the time? What about the sensation that you are physically stuffed, but you still crave food? These experiences point to the fact that there are two types of hunger: short-term and long-term hunger. Many are only aware of short-term hunger, however, In the two examples above, long-term hunger plays a huge role.

Short-Term (Physical) Hunger

I’ll mention Short term hunger first because it is a type of hunger that most people use to gauge are appetite every day. It is the hunger signal that changes from hour to hour based on when you last ate. For example, all things equal, if you ate a large breakfast, you will become full faster when eating lunch. Short-term hunger can be considered physical hunger because it has a lot to do with the physical amount of food that you consume. Let’s look at some of the hunger hormones at play here:

Hunger Hormones

Ghrelin is made in the stomach. It stimulates hunger by entering the brain and acting on the neurons in the hypothalamus to increase the activity of the hunger-causing nerve cells and reducing the activity of hunger-inhibiting cells. As the stomach empties, the release of ghrelin increases. As soon as the stomach is filled, it decreases.

Cholecystokinin (CCK) is produced in the upper small bowel in response to food and gives a feeling of fullness. It is released soon after food reaches the small bowel. Researchers have found CCK can stop a mouse from eating as soon as it’s injected into the brain.

Peptide YY, Glucagon-Like Peptide 1 (GLP-1), Oxyntomodulin and Uroguanylin are all made from the last part of the small bowel and make us feel full. These hormones are released in response to food in the gut.

(Proietto, 2018)

While the above hormones are some of the most important hunger hormones, there are many more that has some effect on hunger:

Diagram of Hunger Hormones:

(Kirkham & Cooper, 2007)

The hormones that increase hunger are listed on the left, and those that suppress hunger are on the right. In addition, the hormones towards the top have the strongest effect, and conversely, those at the bottom produce the weakest effect.

Here’s a hypothetical example of how these hormones work to control appetite…

Let’s say that it is almost time for lunch and you haven’t eaten in a while. You stomach detects that it is empty and thus released Ghrelin, which then travels to the brain and creates the sensation of hunger. Noticing the hunger, you decide to eat a large sandwich. The first thing that happens is that your stomach recognizes that is no longer full and thus stops producing Ghrelin to send to your brain. This stops the hunger sensation, but it doesn’t necessarily create a sense of satiety. A sense of fullness, caused by the release of CKK, actually arrives a few minutes later, when the sandwich makes its way to your small intestines. As the sandwich makes its way further down your digestive system, your body releases the rest of the hunger hormones listed above, which create a signal of fullness and satiety.

Long-Term (Brain) Hunger

While short-term or physical hunger is quite intuitive and easy to understand, long-term or brain hunger is more complex. Due to the fact that brain hunger usually only becomes apparent when someone is above or below his or her setpoint, many people are completely unaware that it exists.

Although the concept of long-term hunger may be harder to grasp, an awareness of this type of hunger is crucial in order to understand your inability to feel satisfied, as well as the intense cravings you might experience while dieting or during metabolic recovery. What’s interesting about long-term hunger is that it cannot be satisfied with a single meal no matter how much you eat. In fact, brain hunger is often misdiagnosed as emotion food cravings because it cannot be fulfilled by food in the short-term. Many with this problem of “emotional eating” find that these cravings disappear once they return to their body weight set point.

How to Fulfill “Brain” Hunger?

Fulfilling long-term hunger requires you to eat to short-term satiety for however long it takes to reach your bodyweight setpoint. Thus, a change in long-term hunger can take as short as few meals, to as long as a few months of consistent eating. I call long-term hunger “brain hunger” because it is not dependent on how physically full your stomach is, but rather the amount of the hormone leptin entering your brain.

Leptin: Long-Term Hunger Hormone

Leptin is a hormone that correlates with the amount of body fat that your carry: all things equal, the higher your body fat percentage, the more leptin you will have and vice versa. This master hormone travels from the fat cells where it is created, into the brain where it then signals the amount of energy storage, aka fat mass.

High Long-Term Hunger While Dieting

Here’s a hypothetical example of how leptin regulates your long-term appetite. Let’s say you have been on a diet for three months and have lost 15 pounds of body fat. While you are happy about losing 15 pounds, it has also led to a reduction in the amount of leptin in your system. Less leptin results in a weaker signal to your brain. This weaker leptin signal indicates to your brain that your energy stores are low, and that it should therefore increase hunger and lower energy expenditure (the number of calories that you burn at rest). The result is that you get hungry much faster, you can eat more per meal, and despite feeling physically full after a meal, your brain may still want more food. If you have ever have dieted or have had an eating disorder you probably have experienced this state. Many dieters are able to trick short-term hunger by eating high volume, low-calorie foods, but this does nothing for your long-term hunger.

Does It Also Work the Other Way Around?

It sure does! In the same way that dieting raises your long-term hunger, eating the proper number of calories for a period of time can return you long-term hunger back to normal. In fact, once people are at or above their bodyweight setpoint, they start to lose their long-term hunger altogether.

Loss of Long-Term Hunger When Bulking

Just to give you an idea of how much longer-term hunger can swing in the opposite direction, let me tell you about my experience losing my appetite completely while “bulking” in high school. To the girls reading this, it might sound crazy, but most guys have had the experience of trying to gain weight for sports or to build muscle in the gym. During my Sophomore year of high school, one of my football coaches encouraged me to gain weight and told me to eat 5,000 calories a day. In order to reach my 5,000-calorie goal, I ate sandwiches and mass gainer shakes between classes. For the first few weeks it was easy, but then it got to the point that even though my stomach still had room, my brain completely rejected the idea of more food. I would get nauseas at the idea of taking another bite of my PBJ sandwich. This loss of long-term hunger was caused by excess leptin which resulted from me being over my bodyweight setpoint. At that point I never could have imagined that just a few years later I would be in the complete opposite position due to strict dieting.

What You Can Takeaway From This Story

I believe that this story gives insight to why many dieters and those naturally lean have a hard time understanding each other. Those that are naturally lean often say, “all you have to do is not eat so much.” Conversely, dieters often advise those underweight: “just eat more, it’s not that hard.” The truth is that many times these two groups experience a similar change in long-term hunger, just in opposite directions.

Are My Hunger Signals Broken?

This is a common question of those who always seem hungry even after meals. Although it may seem like your hunger signal is malfunctioning, it is actually working exactly the way it is supposed to given prolonged caloric restriction.

What If I lost Hunger From Dieting?

While that may sound strange and contradictory, it is quite common for those who have restricted in the past to lose their appetite. However, even in that situation, your hunger signal is not really broken, but rather dormant. After a period of time of forcing yourself to eat a minimum number of calories, your hunger signal will begin to return.

Here is a chart that I made to depict Both Long-Term and Short-Term Hunger…

The chart depicts the change in long-term hunger as someone diets. As shown in the chart, a reduction in calories and loss of body fat results in a rise in long-term hunger. The purple curves represent short-term or physical hunger. As shown, in the top right of the long-term hunger curve, it is possible to be physically full, but yet mentally still hungary.

How are the Two Types of Hunger Related?

Fulfilling short-term hunger consistently over time leads to lower long-term hunger and vice versa.

When long-term hunger is high, it takes more food per meal to satisfy short-term hunger and vice versa.

When long-term hunger is high, your short-term hunger returns faster after meals and vice versa.

References:

Proietto, J. (2018, December 06). Chemical messengers: How hormones make us feel hungry and full. Retrieved from http://theconversation.com/chemical-messengers-how-hormones-make-us-feel-hungry-and-full-35545

Kirkham, T. C., & Cooper, S. J. (2007). Appetite and body weight: Integrative systems and the development of anti-obesity drugs. Amsterdam: Elsevier Academic Press.