Why do people get fat? – Understanding Obesity

If we wish to understand obesity, we first need to understand the hormone leptin, and how it works.

Leptin was observed at the first time at 1994 by scientists. Some scientists call it our starvation hormone or the obese hormone. It is produced inside of our fat cells and its job to tell the brain weather there is a lack or exceeding amount of energy.

Each one of us is born with a certain Leptin “Threshold”. When the leptin levels are going down below that threshold that means there is a lack of energy, and the Leptin hormone will signal the brain that more food is needed. When the Leptin levels are above that threshold, that means that there is enough energy, the Leptin will signal that to the brain and the brain will get into fullness mode. 

Ok that’s nice to know, but it still does not explain why people are getting fat?

Scientists believed that in fat people, we would find low levels of Leptin in the fat cells. Researches showed that there are still high levels of Leptin even in obese people. That was a shock to the researchers and doctor who was investigating the leptin hormone and the way it works.

In overweighed people the problem is that the Leptin is sending the signal to the brain but the brain just will not get it. This phenomenon called Leptin resistance. It is similar to what happens in type 2 diabetes where the body is resistant to insulin. The pancreas would make a lot of insulin but the body won’t react correctly.

The problem is that we have a red line at the bottom when we are short in Leptin, but there is no red line when we are having exceeding amounts of Leptin. When you are resistant to Leptin you have higher level of Leptin which means you are fat. But your brain won’t recognize it. Let’s put it that way, your brain is craving for food while your body is obese, and that’s exactly what obesity is: When your brain is starving.

Leptin is not only tells us when we feel full or hungry. It also has an important role in the rewarding system. The food will be more rewarding when the Leptin levels are low. When the levels are high it should exhaust the rewarding system and make food feel less rewarding, so food will not look as good as before, and make you eat less, or stop eating.

But when you are resistant to Leptin, this rewarding system will not apply, and will not make the person to eat less, when your Leptin levels are high. The fat cells are responsible to create the leptin and by doing so they try to signal the brain that they do not need any more energy, but the brain just don’t get it. You would still feel hungry and food would still look and taste good to you, you would keep eating and eating until you would get obese.

That was exciting news for the obese community since for the first time there was a scientific explanation that was describing their problem, instead of just thinking of them as fat people.