Obesity Surgery Yields Clues to Weight-Loss Mysteries
Surgery forِ obesity began withِ a simple premise: ifِ you makeِ the stomach smaller, people willِ eat less, soِ they willِ lose weight.
Their findings areِ beginning toِ present a farِ more complicated picture ofِ weight — andِ of howِ much diet andِ exercise canِ really doِ to change it.
Chasing downِ the answer toِ exactlyِ how obesity surgery works isِ providing newِ insights intoِ human weight loss andِ appetite regulation, researchers say.
Ghrelin from the gut
There areِ several differentِ types ofِ weight-loss surgery (also called bariatric surgery), including gastric bypass andِ gastric banding, butِ allِ involve making theِ stomach smaller.
Patients canِ lose upِ toِ 60 toِ 80 percent ofِ their excess weight inِ one toِ fourِ years afterِ surgery, andِ many haveِ anِ easier time keeping itِ off thanِ they didِ through dieting, Bhoyrul said.
A key player inِ this difference isِ the hormone ghrelin, whichِ stimulates appetite.
But after gastric bypass surgery, ghrelin levels go down significantly, Burch said.
They’re losing moreِ weight thanِ they everِ had beforeِ andِ not onlyِ areِ not hungry, theyِ haveِ to force themselvesِ to eat, Burch said.
This mayِ beِ why surgery patients canِ keep theirِ weight off, heِ said.
And ghrelin isِ likely justِ the tip ofِ the iceberg inِ terms ofِ hormonal changesِ that occur.
Mind over stomach
Results fromِ the surgery haveِ alsoِ highlighted theِ role ofِ the brain inِ weight loss andِ weight gain.
We neverِ realized thatِ the brain wasِ soِ important, Bhoyrul said.
The brain isِ the body’s energy thermostat, Bhoyrul said, controlling howِ quickly youِ useِ energy, andِ when toِ store andِ expend it.
Deciphering this conversation could help researchers understand how to best instigate weight loss, Bhoyrul said.
A recentِ finding underscores howِ much thereِ isِ to learn aboutِ the stomach-brain connection.
Unlike theِ drop inِ ghrelin seenِ afterِ gastric bypass, thoseِ who undergo gastric banding experience a drop inِ their hunger, butِ not inِ ghrelin, saidِ Dr.
Emma Patterson, a bariatric surgeon inِ Portland, Ore.
Surgery without the surgery
It might be possible to replicate the results of the surgery using drugs.
If weِ canِ understand howِ these surgeries work…we canِ put whateverِ thatِ thing isِ inِ a pill, Patterson said.
One possible target may be an enzyme involved in the production of ghrelin, Burch said.
Indeed, oneِ approach takenِ byِ researchers seeking toِ develop anِ obesity vaccine hasِ beenِ to block theِ hormone’s production.
However, someِ haveِ argued that, becauseِ many hormones areِ involved inِ weight loss, targeting oneِ isِ unlikely toِ helpِ people lose weight.
Most ofِ us areِ skeptical thatِ ‘turning offِ the ghrelin switch’ isِ the universal answer toِ allِ obesity, Bhoyrul said..