Many of us have experienced this, continuing to eat even after feeling full, and that has left us wondering why this happens. It is really quite confusing that our body does differently from what our brain thinks of. Let’s leave it all to hormones, which many believes are the main culprit to this “phenomenon”.
Ghrelin and Leptin
No, they are not twin brothers nor sisters, they are hormones that are responsible for feeling hungry or full.
Ghrelin is a hormone that sends signals to the brain to enhance hunger. It is produced by the stomach and is activated before mealtime. As your body responds to the feeling of hunger by eating, your body stops the secretion of ghrelin, hence the feeling of a full stomach, either physically or psychologically.
Leptin, also called the “satiety hormone”, on the other hand, gives the feeling of fullness. It is a hormone released by the adipose cells and acts on your brain receptors to deter hunger.
The Leptin Connection
Leptin was coined from the Greek word “lepto”, meaning “thin”. As its discovery in the 1990s provided great hope to stop obesity, researchers have compiled a lot of data regarding its effects on human brain, and it was found out that there are more to leptin than just satiety and energy balance.
For one, leptin increases blood pressure among obese people. Additionally, leptin levels are increased when your body feels satisfaction, conversely, there is considerably low levels of leptin when you feel that hunger pangs.
This is where one important concept about leptin comes in, the brain’s reward system.
The Reward System in Your Brain
For a long time, food consumption was regarded only as energy provider for the body. This led to the belief that the human body, more particularly the stomach, is just an automatic machine.
The brain’s reward system points to leptin as the brain rewarder, because it gives the feeling of fullness, thereby making the body feel satisfied.
Other than food, our body feels satisfied and rewarded when we encounter things that gives us pleasure, like watching a feel-good movie, getting a surprise gift, meeting our friends after a long time, and doing things for the sheer fun of it.
Eat and Be Rewarded
Instinctively, we look for food to satisfy our sensation of hunger. We believe that we reward ourselves when we feed our body.
However, leptin’s effect on our body provides the needed balance to our food intake. This hormone, when released, sends signals to the brain, and interprets them as a dimunition of rewards associated with food. Thus, when we see food, the brain signals it as something not really enjoyable. Then we do not get to enjoy our food so much.
There is a certain region in our brain where the chemical dopamine is also recognized as having an effect with our food intake. As neurons communicate with fellow neurons that produce dopamine, its information is sometimes interpreted as a reward signal.
Certain experiments with mice reveal the effects of dopamine in the brain. A technique called “optogenetics” was used on mice, genetically manipulating dopamine-producing neurons to increase their activity and release dopamine.
The experiment showed the relation of dopamine to leptin. True enough, the less leptin you have in your body, the less you experience hunger. Additionally, an increase in leptin may have decreased likeness for sugar.
Leptin and Obesity
Hormones play an important role in our desire to eat even when we feel full. Feeling full, on the other hand, does not necessarily mean physically full stomach. It simply means that our hormones suggest fullness even when it is actually not full. The role of leptin in our body greatly affects us, as they say, the more body fat you have, the higher the leptin levels we have.
Based on the above information, we derive the following:
1.Being full does not necessarily mean a physically full stomach.
2.The feeling of fullness has something to do with leptin, the satiety hormone.
3.The brain processes certain reward values to food, which goes up when we are hungry, where commonly we have lower leptin levels in our blood.
4.Fat tissue hormones dictate how much we want food.
5.High levels of leptin gives us a sensation of fullness, thus we don’t feel much hunger.
6.If the brain does not receive leptin signals, it “looks” for food.
7. Sugar is a brain-rewarding food.