By Aly Walansky
Updated March 01, 2016
Credit: © Vintage Images / Alamy

Did you eat a double cheeseburger an hour ago, but still feel hungry? Turns out, there may be a biological reason many of us can’t stay full.

It’s not all about will power; our hormones play a lot of role in our self-control when we are eating. One hormone, known as Ghrelin, causes those hunger pangs, while leptin, another hormone, is supposed to tell us we are full. As long as the hormones work together everything is fine, but that isn’t always the case.

Scientists in Germany recently completed a study on mice published in the journal Nature Communications, revealing there is a switch in the brain that regulates the way leptin works. An enzyme, known as histone deacetylase 5 (HDAC5), acts as this “switch,” and those who do not produce enough of it gain weight because the leptin can’t do the job it is supposed to.

But do these two components tell the whole story, or just act as a piece of the puzzle?

“The science of hormones related to obesity is a complex one. There are so many hormones, enzymes, and other signals related hunger and satiety, and while grehlin and leptin have been identified as key hormones, there are so many more we haven't uncovered yet,” says Rene Ficek, a Registered Dietitian who is also the Lead Nutrition Expert at Seattle Sutton’s Healthy Eating (SSHE). “In the past, targeting only one enzyme or hormone as a treatment for obesity has been unfruitful. There are not a lot of obesity drugs on the market because of this. While this research is new and exciting, it can hopefully play a role in the bigger picture of obesity. And hopefully this bigger picture will result in more effective treatment options for obesity.”

Aside from the complicated concept of hunger, there’s so much about the brain we don’t know yet. “The hunger center of the brain has been well known for a long time—the hypothalamus. What has not been known are the chemicals that work in this part of the brain. The discovery of these new substances in mice brains is interesting,” says Clifford Segil, DO, neurologist at Providence Saint John’s Health Center in Santa Monica, CA. “Any formal application of altering these substances with any medication in people would be a long way away. Even if a medication was developed to alter the levels of leptin and ghrelin, the scientists would still have to figure out a way only to change the levels in the patient's hypothalamus.”

But the experts agree, hunger is more complicated than any one chemical. “I think this is a good start and more research should be done so safe human trials could possibly be considered in the future,” says Dr. Segil.