Obesity - Your brain and eating

Obesity

Why do I feel hungry or full?

Your brain gathers information from many different parts of your body. It uses some of this information to decide whether you need to eat (or stop eating). So if your brain decides you need extra food or energy, your brain "tells you" you're hungry.

For instance, your brain gets messages from your stomach about whether it's full or empty. So if your stomach is full, you feel less hungry.
A part of your brain also checks how much sugar there is in your blood. You'll start to feel hungry if the amount of sugar drops too low.
The cells in your body that store fat make a chemical called leptin. Scientists think that leptin tells your brain how much fat you have in your body.

Source:
Flier JS.
Obesity.
In: Braunwald E, Hauser SL, Fauci AS, et al (editors). Harrison's principles of internal medicine. 15th edition. McGraw Hill, New York, U.S.A.; 2001.

¹ If there's enough fat in the body, leptin tells your brain that you have enough. This makes you stop eating. A few obese people have a condition where they don't make enough leptin. These people might be helped by treatment with leptin.
Researchers also think that another hormone, called ghrelin (pronounced "grellin'), might affect your weight. Ghrelin makes you feel hungry. It's made mainly in your stomach, although your brain also produces a small amount. The level of ghrelin in your blood rises just before you eat and drops after you eat.

Source:
Eisenstein J, Greenberg A.
Ghrelin: update 2003.
Nutrition reviews. 2003; 61: 101-104.

²

Source:
Hovath TL, Diano S, Heiman ML.
Ghrelin induces adiposity in rodents.
Nature. 2001; 407: 908-913.

³

Source:
Kopelman PG, Grace C.
New thoughts in managing obesity.
Gut. 2004; 53: 1044-1053.

⁴ Researchers are looking to see if blocking ghrelin helps people to eat less and lose weight.

Sources for the information on this page:

Flier JS.Obesity.In: Braunwald E, Hauser SL, Fauci AS, et al (editors). Harrison's principles of internal medicine. 15th edition. McGraw Hill, New York, U.S.A.; 2001.

Eisenstein J, Greenberg A.Ghrelin: update 2003.Nutrition reviews. 2003; 61: 101-104.

Hovath TL, Diano S, Heiman ML.Ghrelin induces adiposity in rodents.Nature. 2001; 407: 908-913.

Kopelman PG, Grace C.New thoughts in managing obesity.Gut. 2004; 53: 1044-1053.

This information was last updated on May 01, 2009

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