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Science Shows Yo-Yo Dieters Probably Can’t Win

by Sandy Todd Webster on Dec 01, 2013

Feature

Repeat dieting can damage the stomach's ability to sense satiety.

Yo Yo

You probably have clients who have been dieting most of their adult lives. A study published in the International Journal of Obesity (2013; doi: 10.1038/ijo.2013.138) shows that there may be a physiologic reason why diets could be a poor bet, especially for obese people.

Researchers from the University of Adelaide in South Australia discovered that the way the stomach detects and tells our brains how full we are becomes damaged in obese people, but the mechanism does not return to normal once those people lose weight. The authors believe this could be a key reason why most people who lose weight on a diet eventually backslide.

PhD student Stephen Kentish investigated the impact of a high-fat diet on the gut's ability to signal fullness, and whether those changes revert to normal upon weight loss. Results show that the nerves in the stomach that signal fullness to the brain appear to become desensitized after long-term consumption of a high-fat diet.

"The stomach's nerve response does not return to normal upon return to a normal diet. This means you would need to eat more food before you felt the same degree of fullness as a healthy individual," said study leader and associate professor Amanda Page from the university's Nerve-Gut Research Laboratory.

"A hormone in the body, leptin, known to regulate food intake, can also change the sensitivity of the nerves in the stomach that signal fullness. In normal conditions, leptin acts to stop food intake,” she reported in a university press release. “However, in the stomach in high-fat diet induced obesity, leptin further desensitises the nerves that detect fullness. These two mechanisms combined mean that obese people need to eat more to feel full, which in turn continues their cycle of obesity."

Page says the researchers are not yet sure whether this effect is permanent. "We know that only about 5% of people on diets are able to maintain their weight loss, and that most people who've been on a diet put all of that weight back on within two years," she notes. "More research is needed to determine how long the effect lasts, and whether there is any way&emdash;chemical or otherwise&emdash;to trick the stomach into resetting itself to normal."

PHOTOGRAPHY: Tammie Crawforth

IDEA Food and Nutrition Tips, Volume 2, Issue 7

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About the Author

Sandy Todd Webster

Sandy Todd Webster IDEA Author/Presenter

Sandy Todd Webster is Editor in Chief of IDEA's publications, including the award-winning IDEA FITNESS JOURNAL and IDEA FOOD & NUTRITION TIPS, the industry's leading resources for fitness, wellness and nutrition professionals worldwide. Sandy joined IDEA in 2001 as executive editor of IDEA PERSONAL TRAINER and IDEA FITNESS MANAGER magazines and was promoted to lead the editorial team in 2003. More than 20 years in magazine publishing, marketing communications and creative services have shaped her straightforward approach to multi-channel communication. Early experience in Los Angeles as a sports writer/reporter, and then enriching years as a managing editor in allied health care publishing have pulled her across a spectrum of stimulating subject matter. Fitness, health and nutrition reside at the perfect center of this content continuum, she feels. A Chicago native, Sandy grew up fully engaged in various competitive sports. Her drive and dedication as an athlete translate to a disciplined work ethic and unwavering approach to challenge in her career. Shortly after graduating journalism school from Southern Illinois University-Carbondale, she was recruited to L.A. for her first post in magazine publishing. After two decades of working on magazines--and now in the throes of applying the unbelieveable multi-media content delivery options available in the magazine 2.0 world--she is still "completely in love" with the creative process it takes to deliver meaningful, inspirational content to end users. She is an accomplished home cook and gardner who would love to combine those skills and passions with her health and fitness background to continue educating readers about a well-balanced, healthy lifestyle.