We commonly think a full stomach is what tells us to stop eating, but it may be that a stretched intestine plays an even bigger role in making us feel sated, according to new research from the University of California in San Francisco.
You may not believe it, especially heading into the holiday season, but your body is remarkably good at keeping your weight within an extremely narrow range in the long run, which it does by balancing how much you eat with how much energy you expend each day.
How your gut helps control your food intake
The extensive web of nerve endings that line your gut plays an important role in controlling how much you eat. It does so by monitoring the contents of the stomach and intestine and then sending signals back to the brain that increase or reduce your appetite.
Most scientists believe this feedback involves hormone-sensitive nerve endings in the gut that track the nutrients you consume and calculate when you've had enough. But no one has yet tracked down the exact type of neurons that convey these signals to the brain.
One of the challenges to answering this question is that the thousands of nerves involved in collecting sensory information from the stomach and intestine come in many different types. And all of them transmit messages back to the brain via the same giant bundle, called the vagus nerve.
Scientists can either block or stimulate the activity of the vagus nerve and change animals' appetites, but how do you figure out which vagal nerve endings in particular were responsible for the change?
About the study
To resolve answer this, the research team comprehensively mapped the molecular and anatomical identities of the vagal sensory cell types neurons innervating the stomach and intestine. This map allowed the researchers to selectively stimulate different types of vagal neurons in mice, revealing that intestinal stretch sensors are uniquely able to stop even hungry mice from wanting to eat.
To the researchers' surprise, they found that stimulating stretch receptors in the intestine proved much more powerful at eliminating the appetites of the hungry mice than the stomach stretch receptors.
This was unexpected because the dogma in the field for decades has been that stomach stretch receptors sense the volume of food being eaten and the intestinal hormone receptors sense its energy content.
Source: Cell, November 14, 2019.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.