There are 3 hormones which are primarily responsible for how hungry we feel.
The first is ghrelin, which stimulates hunger; it is produced in the stomach and during fasting
periods levels of ghrelin are elevated. Overweight people have less ghrelin than others, and
irregular sleep can effects its natural production.
The second is peptide YY (PYY), which suppresses appetite and is released by the ilium approximately
15mins after you start eating.
Overweight people produce less PYY than normal, and so will not feel as satisfied after a
meal; this could be an effect of being overweight rather than a cause though. The purpose of
PYY is to prevent over eating.
The third is leptin, which suppresses appetite, and is produced, in adipose fat. Levels of
circulating leptin are proportional to the amount of adipose fat, meaning that overweight
people produce more.
Some sugars such as high fructose corn syrup can inhibit the action of leptin, and regular
over eating can make an individual resistant. The purpose of leptin is to help maintain
a healthy amount of body fat, and prevent obesity.
For more information on hunger hormones please visit the link in the description.
