A scientific breakthrough / further explains / why people get hungry / at mealtimes, / why dieters may struggle to maintain weight loss, / and why stomach surgery may be an effective treatment / for dangerously overweight patients.

The answer is ghrelin, / a naturally occurring hormone / that causes hunger / and slows the body's fat-burning capacity.

New research indicates / that dieters experience / increased production of ghrelin / when they lose weight.

This drives them to eat, / forcing them to put the weight back on.

In patients / who have received a surgical operation / called a gastric bypass, / however, / ghrelin levels remain low, / so they do not have the same hunger pains.

Ghrelin is one of many substances / produced naturally in the body / that pass messages / between the brain and the digestive system.

It is the first natural appetite stimulant / found to be produced / outside the brain; / it is produced by specialized cells / in the stomach.

Since it occurs / outside the brain, / it may be an easier target / for scientists searching for a way / to control appetite.

The hope is / that medications that decrease or block ghrelin / may be developed, / which would help obese people / lose weight / and keep it off.

Likewise, / medications that boost ghrelin levels / may lead dangerously thin cancer patients / to recover their appetite.

In short, / ghrelin could be the key / to finding workable solutions / to weight control problems.