Students, Faculty Study the Science of Gaining Weight
It may not always be as simple as it sounds, but, in general,
stress, sleep deprivation and estrogen loss can make you gain weight.
That’s according to Gwyneth Beagley, whose recent research with students Melissa Barclay ’08 and Kathryn Krauss ’09 analyzed how stress, sleep and aging affect appetite and weight gain.
Beagley, professor of psychology at Alma College, is writing a book on the physiology of eating, hunger signaling from the body to the brain, and the interactions among important hormones like leptin (which regulates appetite), ghrelin (which prompts hunger) and insulin.
Gwyneth Beagley and students study the physiology of eating.
“Levels of leptin and ghrelin influence whether you are eating
or not,” says Beagley. “In research studies, mice bred not to produce
leptin will eat and gain significant weight. Add leptin, they go back
to regular size. At one time, scientists thought leptin was a cure for
obesity, but it’s not.
“Obesity may result from a problem with the receptors in the brain that receive the hormonal signals from the body,” she says. “The older you get, there is a loss of receptor sensitivity. So one can say age makes you gain weight.”
When someone is stressed, the brain sends a signal to the hypothalamus, the part of the brain that links the nervous system to the endocrine system via the pituitary gland, which results in the release of body chemicals such as adrenaline and steroids to deal with the stress, says Beagley. If the stress is sudden and threatening, the adrenaline provides the energy to run away or respond physically. The steroids deliver sugar to the muscles to help the heart beat faster in response to the sudden stress.
However, stress related to on-going worries also produces adrenaline and steroids that cause a different affect.
“Steroids are not great for dealing with on-going stress,” says Beagley. “They make you hungry by interfering with leptin. Steroids also store food around your middle.”
Regarding Sleep Deprivation:
Studies show that people in general are getting less and less sleep — from an average of eight to nine hours a night 50 years ago to an average of five to six hours now. In addition, multiple studies indicate an increase in obesity. In response, Beagley and Barclay conducted research on the relationship of sleep deprivation and obesity.
Using rats as her subjects, Barclay placed groupings of rats in different environments — some in large colony rooms and others in small spaces, some subjected to loud music to inhibit their sleep, and some with Oreo cookies. Research results indicated that the sleep-deprived rats with access to lots of cookies were the fattest — more so than rats that weren’t sleep deprived.
Barclay’s study supported another (non-Alma-related) study with healthy college students who were limited to four hours of sleep per night. Researchers found that the sleep-deprived students tended to eat more. Their calorie intake increased while their leptin levels decreased.
Regarding Estrogen Loss:
Krauss and Beagley also worked with female rats in a study on estrogen loss. Estrogen removal causes weight gain and in increase in appetite, says Beagley. In her study, Krauss removed estrogen in some rats and put some rats on high-fat diets. Among the various groups, the fattest rats were those that had no estrogen and high-fat diets.
Research by Beagley and her students continue as she works on her book manuscript.
“We’re looking at the histology of brain tissue to see if behavioral changes are reflected with brain morphology changes,” says Beagley.
Posted: Thu, October 9th, 2008 at 3:44PM