Estrogen helps brain keep weight in check
Posted by on November 3, 2011 - 2:44pm

A recent UT Southwestern Medical Center study found that estrogen regulates energy expenditure, appetite and body weight, while insufficient estrogen receptors in specific parts of the brain may lead to obesity.

“Estrogen has a profound effect on metabolism,” said Dr. Deborah Clegg, associate professor of internal medicine and senior author of the study published Oct. 5 in Cell Metabolism. “We hadn’t previously thought of sex hormones as being critical regulators of food intake and body weight.”

The mouse study is the first to show that estrogen, acting through two hypothalamic neural centers in the brain, keeps female body weight in check by regulating hunger and energy expenditure. Female mice lacking estrogen receptor alpha – a molecule that sends estrogen signals to neurons – in those parts of the brain became obese and developed related diseases, such as diabetes and heart disease.

Similar results were not seen in male mice, although researchers suspect other unknown estrogen receptor sites in the brain play a similar role in regulating metabolism for males as well. Estrogen receptors are located throughout the body, but researchers found two specific populations of estrogen receptors that appear to regulate energy balance for female mice.

The findings are potentially important for millions of postmenopausal women, many of whom have decided against hormonal replacement therapy. The study could lead to new hormonal replacement therapies in which estrogen is delivered to specific parts of the brain that regulate body weight, thereby avoiding the risks associated with full-body estrogen delivery, such as breast cancer and stroke.

Doctors stopped routinely recommending long-term estrogen therapy for menopausal women in 2002 when a Women’s Health Initiative study showed the hormone did not prevent heart disease in women who already were at increased risk.

“The role of estrogen in postmenopausal women continues to remain uncertain,” Dr. Clegg said. “Current research is focused on the timing and the type of estrogen supplementation that would be most beneficial to women. Our findings further support a role for estrogens in regulating body weight and energy expenditure, suggesting a benefit of estrogen supplementation in postmenopausal women.”

Source: UT Southwestern Medical Center

 

Night Owls at Risk for Weight Gain
Posted by on May 21, 2011 - 8:57am

Staying up late every night and sleeping in is a habit that could put you at risk for gaining weight. People who go to bed late and sleep late eat more calories in the evening, more fast food, fewer fruits and vegetables and weigh more than people who go to sleep earlier and wake up earlier, according to a new Northwestern Medicine study.

Late sleepers consumed 248 more calories a day, twice as much fast food and half as many fruits and vegetables as those with earlier sleep times, according to the study. They also drank more full-calorie sodas. The late sleepers consumed the extra calories during dinner and later in the evening when everyone else was asleep. They also had a higher body mass index, a measure of body weight, than normal sleepers.

The study is one of the first in the United States to explore the relationship between the circadian timing of sleeping and waking, dietary behavior and body mass index. The study was published online in the journal Obesity and is expected to appear in a late summer print issue.

“The extra daily calories can mean a significant amount of weight gain – two pounds per month – if they are not balanced by more physical activity,” said co-lead author Kelly Glazer Baron, a health psychologist and a neurology instructor at Northwestern University Feinberg School of Medicine.

“We don’t know if late sleepers consume the extra calories because they prefer more high-calorie foods or because there are less healthful options at night,” said co-lead author Kathryn Reid, research assistant professor in neurology at the Feinberg School.

The study shows not only are the number of calories you eat important, but also when you eat them -- and that’s linked to when you sleep and when you wake up, noted senior author Phyllis Zee, M.D., professor of neurology and director of the Sleep and Circadian Rhythms Research Program at Feinberg and medical director of the Sleep Disorders Center at Feinberg and Northwestern Memorial Hospital.

“Human circadian rhythms in sleep and metabolism are synchronized to the daily rotation of the earth, so that when the sun goes down you are supposed to be sleeping, not eating,” Zee said. “When sleep and eating are not aligned with the body’s internal clock, it can lead to changes in appetite and metabolism, which could lead to weight gain.”

The research findings could be relevant to people who are not very successful in losing weight, Zee said. “The study suggests regulating the timing of eating and sleep could improve the effectiveness of weight management programs,“ she said.

The findings also have relevance for night-shift workers, who eat at the wrong time of day related to their bodies’ circadian rhythms. “It’s midnight, but they’re eating lunch,” Zee said. “Their risk for obesity as well as cardiovascular, cerebrovascular and gastrointestinal disorders is higher.”

The study included 51 people (23 late sleepers and 28 normal sleepers) who were an average age of 30. Late sleepers went to sleep at an average time of 3:45 a.m., awoke by 10:45 a.m., ate breakfast at noon, lunch at 2:30 p.m., dinner at 8:15 p.m. and a final meal at 10 p.m. Normal sleepers on average were up by 8 a.m., ate breakfast by 9 a.m., lunch at 1 p.m., dinner at 7 p.m., a last snack at 8:30 p.m. and were asleep by 12:30 a.m.

Participants in the study recorded their eating and sleep in logs and wore a wrist actigraph, which monitors sleep and activity cycles, for at least seven days.

Late sleepers function in society by finding jobs where they can make their own hours, Baron noted, such as academics or consultants. “They find niches where they can live this lifestyle, or they just get by with less sleep,” she said.

Northwestern researchers are planning a series of studies to test the findings in a larger community and to understand the biological mechanisms that link the relationship between circadian rhythms, sleep timing and metabolism.
by Marla Paul, health sciences editor, Feinberg School of Medicine. Contact her at marla-paul@northwestern.edu

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Battling the Weight-loss Plateau
Posted by on May 18, 2011 - 10:47am

Have you been losing weight and despite staying on your diet and exercising, your weight suddenly stays the same?   Don't get discouraged, it's normal for weight loss to slow down and even stop.   This phenomenon is called the "weight-loss plateau" and it's more common than you think.  Even the best planned weight loss program can become stalled.

According to the Mayo Clinic, here's why this happens.   A rapid weight loss is common during the first few weeks of a well planned diet.  When calories are reduced the body gets needed energy by releasing its stores of glycogen, a type of carbohydrate stored in the liver and muscles.   Glycogen holds a lot of water so when it is used up at the beginning of a diet, it also releases the water--about 4 grams per gram of glycogen, resulting in a sudden weight loss that is mostly water.

Once your diet progresses and  you start burning lean muscle tissue, your metabolism slows.  Metabolism is the process of converting food into energy.  When you lose weight you lose fat and lean muscle and this weigh-loss changes once your metabolism slows.   At this point,  you need to increase your exercise or decrease your food intake if you want to lose more weight.   If you continue the diet/exercise regimen you started with, you will maintain your weight but probably not continue to drop many pounds.

To get past this weight loss plateau, you need to

  • Review your eating/exercise habits and be sure you haven't "cheated" along the way
  • Cut more calories--try reducing your diet by 200 more calories
  • Increase your workout...either in time or intensity
  • Try to increase movement during the day----take stairs instead of the elevator, run your errands on foot.
  • Applaud your success and make sure your goals are reasonable--just don't fall back.