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Mental Health, Nutrition, Obesity, Research, Women's Health

Stressed? You could be burning fewer calories

Stressed? You could be burning fewer calories

cupcakesBad news, ladies: Findings (subscription required) recently published in Biological Psychiatry show that women who consumed comfort food while feeling stressed burned fewer calories than their zen-like counterparts.

In the study, Ohio State University researchers quizzed a group of women about what was causing stress in their lives before they ate a caloric meal consisting of eggs, turkey sausage, biscuits and gravy. Scientific American reports:

Turns out that the most stressed women had higher levels of insulin. Which slows down metabolism and causes the body to store fat. And that fat, if not burned off, accumulates in the body.

The women who had reported feeling stressed or depressed in the day before eating the meal burned 104 fewer calories during the seven hours following the meal than women who felt more mellow.

If eating high-calorie comfort food to alleviate stress becomes habitual, the result could be an average weight gain of 11 pounds per year.

So next time you’re feeling overwhelmed and exhausted, you might want to reconsider reaching for a cupcake.

Previously: Learning tools for mindful eating, Mindful eating tips for the desk-bound and Want to curb junk food cravings? Get more sleep
Photo by Class V

Obesity, Parenting, Pediatrics, Research, Sleep

Study shows poor sleep habits as a teenager can “stack the deck against you for obesity later in life”

Study shows poor sleep habits as a teenager can "stack the deck against you for obesity later in life"

11386276_c148dfd9bd_zNew research examining the effect of sleeplessness on weight gain in teenagers over time offers strong evidence that inadequate sleep may increase the risk of obesity.

In the study, researchers at Columbia University and the University of North Carolina pored over health information from the the National Longitudinal Study of Adolescent Health on more than 10,000 Americans ages 16 and 21. In addition, details about individuals’ height, weight and sleep habits were collected during home visits in 1995 and 2001.  According to a release, results showed:

Nearly one-fifth of the 16-year-olds reported getting less than six hours of sleep. This group was 20 percent more likely to be obese by age 21, compared to their peers who got more than eight hours of sleep. While lack of physical activity and time spent watching television contributed to obesity, they did not account for the relationship between sleeplessness and obesity.

“Lack of sleep in your teenage years can stack the deck against you for obesity later in life,” says [Columbia researcher Shakira Suglia, ScD]. “Once you’re an obese adult, it is much harder to lose weight and keep it off. And the longer you are obese, the greater your risk for health problems like heart disease, diabetes, and cancer.”

“The message for parents is to make sure their teenagers get more than eight hours a night,” adds Suglia. “A good night’s sleep does more than help them stay alert in school. It helps them grow into healthy adults.”

Previously: Want teens to eat healthy? Make sure they get a good night’s sleepProlonged fatigue and mood disorders among teensMore evidence linking sleep deprivation and obesityStudy shows link between lack of sleep and obesity in teen boys and Study shows lack of sleep during adolescence may have “lasting consequences” on the brain
Photo by Adrian Sampson

From August 11-25, Scope will be on a limited publishing schedule. During that time, you may also notice a delay in comment moderation. We’ll return to our regular schedule on August 25.

Evolution, Genetics, Obesity, Research, Science, Stanford News

Tiny fruit flies as powerful diabetes model

Tiny fruit flies as powerful diabetes model

Seung Kim

Fruit flies in your kitchen are unquestionably annoying. But the next time you’re trying to bat one out of the air around your too-ripe apples and bananas (or maybe that’s just me?), spare a few seconds to realize how important the tiny insects have been to science. They’ve been a darling of developmental biology for decades, as researchers identified genes (subsequently shown to be shared in mammals and humans) critically important in the metamorphosis from egg to animal. Frankly, it’s hard to over-estimate their contribution to science.

Now they’re set to take up a starring role in diabetes research. Stanford developmental biologist and Howard Hughes Medical Institute investigator Seung Kim, MD, PhD, and research associate Sangbin Park, PhD, have devised a way to measure insulin levels in fruit flies at the picomolar level – the level at which insulin concentrations are measured in humans. They’ve done so by successfully tagging the fruit fly insulin-like-peptide 2, or Ilp2, with a chemical tag. Their research was published today in PLOS Genetics.

From our release:

The experimental model is likely to transform the field of diabetes research by bringing the staggering power of fruit fly genetics, honed over 100 years of research, to bear on the devastating condition that affects millions of Americans. Until now, scientists wishing to study the effect of specific mutations on insulin had to rely on the laborious, lengthy and expensive genetic engineering of laboratory mice or other mammals.

In contrast, tiny, short-lived fruit flies can be bred in dizzying combinations by the tens of thousands in just days or weeks in small flasks on a laboratory bench.

In 2002, Kim and developmental biologist Roel Nusse, PhD, surprised many researchers when they showed that fruit flies develop a diabetes-like condition when their insulin-producing cells are destroyed. Further research has been stymied, however, by the difficulty of accurately measuring circulating insulin levels in the tiny animals. When speaking to me about the research, Kim called the new technique a “breakthrough” in the field.

Unlike many previous attempts by many groups, Park found two places in Ilp2 where the tag can be placed without affecting its biological activity. This allowed Kim and Park to track Ilp2 through its life cycle, as it’s produced by neurons in the brain (this is different from humans, who make insulin in beta cells in the pancreas), secreted into the blood stream and binds to insulin receptors in cells throughout the body. Parsing the effect of each mutation on the way the body produces, secretes and responds (or not) to insulin is critical to further understand the disease and to devise new therapeutic approaches. More from our release:

Park and his colleagues then turned their attention to mutations associated with type-2 diabetes in genome-wide studies in humans. These studies don’t reveal how a specific mutation might work to affect development of a disease; they show only that people with the condition are more likely than those without it to have certain mutations in their genome. Hundreds of candidate-susceptibility genes have been identified in this way.

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Health and Fitness, Nutrition, Obesity, Parenting, Pediatrics, Stanford News

Childhood obesity expert to parents: Reduce your child’s screen time

Childhood obesity expert to parents: Reduce your child's screen time

screen-tvTake a few minutes to read a brief and informative piece about the negative health effects of too much screen time for children and how you can set boundaries for your kids – or perhaps yourself. In a Stanford Medicine News Q&A, pediatrician Thomas Robinson, MD, MPH, director of the Center for Healthy Weight at Lucile Packard Children’s Hospital Stanford, explains how watching TV or playing video games contributes to inactivity, overeating and obesity. Robinson also speaks to the modern-day concern of restricting access to screen devices that can also be educational tools, such as the iPad.

From the Q&A:

What’s the relationship between excessive screen time and childhood obesity?

It’s a true cause-and-effect relationship. The more time kids spend with screens, the less time they are spending being active. The best evidence supports two primary mechanisms—that kids eat more while watching screens and that exposure to food advertising leads to an increased eating of high-sugar, high-fat and calorie-dense foods. Lots of research shows that kids—and adults—eat more when distracted by a screen. So one of the most important things a family can do is eliminate eating while watching TV and other screens.

Previously:  Talking to kids about junk food ads, This is your 4-year-old on cartoons, Study: Too much TV, computer could hurt kids’ mental health, Does TV watching, or prolonged sitting, contribute to child obesity rates? and Paper explores effects of electronic media on kids’ health

Health and Fitness, Obesity, Research, Stanford News

Without exercise, Americans are growing more obese, according to Stanford researchers

Without exercise, Americans are growing more obese, according to Stanford researchers

gym_smallerMore than half of all American women don’t exercise at all, according to a survey that tracked the health of nearly 7,000 people in 2009 and 2010. Men don’t fare much better: 43 percent don’t work out at all.

Those percentages are dramatically higher than results from a similar study conducted in the early 1990s, which uncovered only 19 percent of sedentary women and 11 percent of inactive men.

More troubling, obesity rates jumped during the same period, according to an analysis by Stanford researchers published in the August issue of The American Journal of Medicine and now available online in a draft form.

What gives? Experts have been intoning “exercise 30 minutes a day most days” for more than a decade. People are just lazy, right?

It’s not that simple, says Pamela Powers Hannley, MPH, the journal’s editor, in a sharply worded commentary that accompanies the study. Many women work long hours, then spend their “spare” time parenting, not jogging, Hannley said. Exercise alternatives need to be convenient and low-cost, Hannley said, noting that some communities, like Tucson, Arizona, where she lives, are considering reducing hours at swimming pools or even closing pools entirely to save money.

“It’s going to take widespread change, not just individual change, not just an app for your iPhone,” Hannley says.

She, along with primary study author Uri Ladabaum, MD, associate professor of gastroenterology, heartily endorse the five recommendations issued by the Institute of Medicine in 2012. They are: integrate physical activity into daily life; make healthy food choices easy and routine; reinvigorate messages about exercise and food; focus on schools; and expand the role of employers, medical professionals and insurers.

Some people, including my editor here at Stanford, aren’t convinced that exercise can single-handedly curb obesity. Diet, the other obvious causal factor, didn’t play a leading role in this data set. The study considered the total calories consumed, but that didn’t vary significantly from 1988 to 2010, Ladabaum and his colleagues write. Genetics, environment and plain ‘ol chance all play a role in overall weight.

This study dug up another worrying trend, as well, one that particularly jumped out to second author, Ajitha Mannalithara, PhD, a Stanford social science research associate: Independent of weight, Americans are getting thicker around the middle.  The incidence of so-called abdominal obesity climbed from 46 percent to 62 percent in women and from 29 to 42 percent in men.

Abdominal girth is linked to increased risks of cancer and cardiovascular disease, even in normal weight individuals, Mannalithara said.

The stats are all based on the robust National Health and Nutrition Examination Survey, a long-term project of the Centers for Disease Control and Prevention that collects information from both surveys and physical examinations to assess Americans’ health.

Becky Bach is a former park ranger who now spends her time writing, exploring, or practicing yoga. She’s currently a science writing intern in the medical school’s Office of Communication & Public Affairs.

Previously: Lack of exercise shown to have largest impact on heart disease risk for women over 30, More evidence that boosting Americans’ physical activity alone won’t solve the obesity epidemic, To meet weight loss goals, start exercise and healthy eating programs at the same time and Study shows regular physical activity, even modest amounts, can add years to your life
Photo by Ms. Phoenix

Behavioral Science, Health and Fitness, Obesity, Research, Stanford News

The behavioral consequences of overindulgence

The behavioral consequences of overindulgence

sundae_070714In today’s world of Big Gulps and supersized portions, one giant question looms: How does overindulgence affect our pleasure of food?

To provide an answer, Baba Shiv, MBA, PhD, a professor at the Stanford Graduate School of Business, and colleagues performed a series of experiments investigating how your feeling of satiety impacts the likelihood that you’ll soon eat the same food again. Their findings offer insights for both individuals that have trouble eating and drinking in moderation and those who are picky eaters.

During the first study, students tried three different flavors of crackers, selected their favorite and then were instructed to eat a specific number. They rated their enjoyment after eating each one. According to a business school release:

The students who ate the larger portion (15 crackers) reported significantly lower enjoyment than those who ate the smaller portion (3 crackers).

These findings replicate previous ones on “sensory-specific satiety”: Each bit of the same food is less pleasant than the one before it. Thus, the bigger the portion, the less enjoyment you get out of the last few bites.

More importantly, participants’ enjoyment of the last cracker (manipulated by portion size) seemed to influence how soon the students wanted to eat the crackers again: Participants who ate a small portion typically opted to receive a giveaway box of [crackers] sooner than did participants who ate the larger portion.

In another study exploring behaviors of finicky eaters, study authors gave one group of participants sips of juice and two crackers to eat. A second group was also given the juice and crackers, but had the added distractor task of counting “e’s” in a series of passages before drinking more juice. Results showed that the crackers partially reset their satiety level, allowing students to find the second sip of juice as enjoyable as the first. Shiv notes in the release how these findings could be useful for parents trying to get their little ones to eat more veggies:

Parents of picky eaters could keep this lesson to heart, says Shiv. Rather than insisting that your child eat every last bite of broccoli, introduce another taste in the middle of the serving of broccoli, to reset levels of satiety. Next time there’s broccoli on the plate, your youngster may be more willing to eat it again.

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Big data, Obesity, Pregnancy, Public Health, Women's Health

Maternal obesity linked to earliest premature births, says Stanford study

Maternal obesity linked to earliest premature births, says Stanford study

preemiefeetExpectant mothers who are obese before they become pregnant are at increased risk of delivering a very premature baby, according to a new study of nearly 1,000,000 California births.

The study, which appears in the July issue of Paediatric and Perinatal Epidemiology, is part of a major research effort by the March of Dimes Prematurity Research Center at Stanford University School of Medicine to understand why 450,000 U.S. babies are being born too early each year. Figuring out what causes preterm birth is the first step in understanding how to prevent it, but in many cases, physicians have no idea why a pregnant woman went into labor early.

The new study focused on preterm deliveries of unknown cause, starting from a database of nearly every California birth between January 2007 and December 2009 to examine singleton pregnancies where the mother did not have any illnesses known to be associated with prematurity.

The researchers found a link between mom’s obesity and the earliest premature births, those that happen before 28 weeks, or about six months, of pregnancy. The obesity-prematurity connection was  stronger for first-time moms than for women having their second or later child. Maternal obesity was not linked with preterm deliveries that happen between 28 and 37 weeks of the 40-week gestation period.

From our press release about the research:

“Until now, people have been thinking about preterm birth as one condition, simply by defining it as any birth that happens at least three weeks early,” said Gary Shaw, DrPH, professor of pediatrics and the lead author of the new research. “But it’s not as simple as that. Preterm birth is not one construct; gestational age matters.”

The researchers plan to investigate which aspects of obesity might trigger very early labor. For example, Shaw said, the inflammatory state seen in the body in obesity might be a factor, though more work is needed to confirm this.

Previously: How Stanford researchers are working to understand the complexities of preterm birth, A look at the world’s smallest preterm babies and New research center aims to understand premature birth
Photo by Evelyn

Obesity, Research, Stanford News

Secrets of fat cells discovered

Secrets of fat cells discovered

fat_and_skinnyWhy aren’t we all drowning in fat? Before talking with Mary Teruel, PhD, this question certainly never occurred to me. (On a personal level, though, I admit I’ve wondered about the opposite!) But after our conversation I saw why it’s such a good question — and how great it is that Teruel has come up with an answer.

Normally your body replaces about 10 percent of your fat cells a year, explained Teruel, a Stanford assistant professor of chemical and systems biology. Little by little, the old ones die, and new ones develop from flat, spindly precursor cells.

Teruel knew, based on her previous experiments, that the switch that triggers the conversion of precursor cells into fat cells is an “on-off” sort, not a dimmer which can be dialed up and down.

Here’s what’s going on in a little more detail: The switch controls the amount of PPAR-gamma in a cell. PPAR-gamma is a nuclear receptor protein that is the master regulator of fat-cell development. In precursor cells, the switch is in the “off-state” and there’s no PPAR-gamma in the cell, but when the cell senses a stimulus that can cause fat cell development, the switch flips to the “on-state” and the cell rapidly makes huge amounts of PPAR-gamma which then turns on hundreds of downstream genes that create a full-fledged fat cell over a period of up to 12 days.

So here’s what was puzzling Teruel: Every human has a large number of precursor cells that all sense the same stimulus, but rather than all converting at once to fat cells (causing us to “drown in fat”) for a given strong stimulus, only a few cells develop into fat cells at any given time, allowing a healthy, constant renewal of our fat tissue. What allows this slow, controlled renewal of fat cells, as well as prevents the unhealthy situation in which all fat cells would turn back into precursors when PPAR-gamma drops below the threshold needed to flip the switch on?
If you can manipulate the rate fat cells mature, you could do a lot for obesity.
Experiments she did with postdoctoral researcher Robert Ahrends, PhD, and colleagues, explain, and provide clues about how to control the rate at which fat forms.

The answer, they discovered, has two parts. First of all, they discovered that the master fat-regulator switch has multiple layers of feedback. Teruel, who has a PhD in aeronautical engineering, explains that these multiple layers allow the body to control the rate of fat cell formation much as a pilot would control the pitch of an aircraft. Second, they found that not all precursor cells are alike — they vary in the quantity they carry of PPAR-gamma and other regulatory proteins.

This realization is a big deal. For one thing, it gives researchers new ideas for treating obesity and diabetes — so far, conditions that resist effective treatment without serious side effects.

“If you can manipulate the rate fat cells mature, you could do a lot for obesity,” she pointed out.

“This might be the heart of how you treat disease,” said Teruel. “We can’t just use one drug for treatment. Disease is more complicated than people think. It would be like trying to control an airplane and only being able to turn the rudder. This might work in a car or boat, but an airplane can move in three-dimensions, and a change in any one dimension affects the other two. Only controlling one dimension is a sure way to crash the plane.”

Teruel’s Stanford website has more info about her research as well as a striking depiction of a fat cell’s development.

They published the results of their studies on Friday in the journal Science (subscription required). They were supported by Stanford University New Faculty Startup Funds, the National Institutes of Health (grant P50GM107615), the German Research Foundation, and the American Heart Association.

Previously: Early findings show nutrigenomics could make weight loss more efficient, Study shows banning soda purchases using food stamps would reduce obesity and type-2 diabetes, Fed Up: A documentary looks for answers about childhood obesity
Photo by Jason Eppink

Health and Fitness, Obesity, Sleep

Why your sleeping habits may be preventing you from sticking to a fitness routine

Why your sleeping habits may be preventing you from sticking to a fitness routine

sleep_06.03.14New research suggests that a later bedtime is associated with a person spending more time sitting during the day and being less motivated to exercise.

The study involved a group of more than a hundred healthy adults with a self-reported sleep duration of at least six and a half hours. Researchers measured sleep variables over the course of a week using wrist actigraphy along with sleep diaries. Participants completed questionnaires about their physical activity and attitudes toward exercise. According to an American Academy of Sleep Medicine release, study results showed:

…that later sleep times were associated with more self-reported minutes sitting, and sleep timing remained a significant predictor of sedentary minutes after controlling for age and sleep duration. However, people who characterized themselves as night owls reported more sitting time and more perceived barriers to exercise, including not having enough time for exercise and being unable to stick to an exercise schedule regardless of what time they actually went to bed or woke up.

“We found that even among healthy, active individuals, sleep timing and circadian preference are related to activity patterns and attitudes toward physical activity,” said principal investigator Kelly Glazer Baron, PhD, associate professor of neurology and director of the Behavioral Sleep Medicine Program at the Feinberg School of Medicine at Northwestern University in Chicago, Illinois. “Waking up late and being an evening person were related to more time spent sitting, particularly on weekends and with difficulty making time to exercise.”

In their conclusion, researchers suggested that sleep habits – particularly those of adults who are less active – be taken into consideration as part of exercise recommendations and interventions.

Previously: Expert argues that for athletes, “sleep could mean the difference between winning and losing”, Ask Stanford Med: Cheri Mah responds to questions on sleep and athletic performance, A slam dunk for sleep: Study shows benefits of slumber on athletic performance and Want to be like Mike? Take a nap on game day
Photo by Becky Wetherington

Genetics, Nutrition, Obesity, Research

Early findings show nutrigenomics could make weight loss more efficient

Early findings show nutrigenomics could make weight loss more efficient

Bieler2“Food is your best medicine,” a wise saying and a book by the late Henry Bieler, MD, holistic doctor to the stars, includes testimonials by Gloria Swanson and Greta Garbo and a recipe for an alkalizing broth comprising four green vegetables to which he attributes all kinds of health benefits. My former ballet teacher (1919-2012) used to eat the broth according to his instructions whenever she was sick, almost sick, or feeling “toxic” for any reason, and I make it now and then just in case it works.

Well, science is moving toward grounding some beliefs about the healing power of certain foods for certain people and the effectiveness of diets tailored to a person’s genetic makeup. A New Scientist piece reports that last week at the European Society of Human Genetics meeting in Milan, University of Trieste researcher Nicola Pirastu, PhD, and colleagues presented findings on nutrigenomics showing that diets shaped according to a person’s metabolism may be more effective than non-specialized calorie reduction in helping him or her lose weight.

From the piece:

The team used the results of a genetic test to design specific diets for 100 obese people that also provided them with 600 fewer calories than usual. A control group was placed on a 600-calorie deficit, untailored diet.

After two years, both groups had lost weight, but those in the nutrigenetic group lost 33 per cent more. They also took only a year to lose as much weight as the group on the untailored diet lost in two years.

I’ll keep eating four green vegetables in their cooking water (and adding Bieler-taboo salt and pepper) until a larger, randomized trial tells me otherwise, but it’s worth considering that “healthy” isn’t one-size-fits-all. The piece continues:

[John Mathers, PhD, director of the Human Nutrition Research Centre at Newcastle University, UK] says the effects of even a healthy diet can vary according to someone’s genetics. For instance, the APOE gene is linked to the breakdown of fat, and one variant of it confers a higher risk of getting cardiovascular disease and dementia. “People with that variant respond differently to certain fats in the diet,” he says. Another gene affects how much vitamin B9 people need.

Previously: Stanford geneticist talks tracking biological data points and personalized medicine, Ask Stanford Med: Genetics chair answers your questions on genomics and personalized medicine and How genome testing can help guide preventative medicine
Photo by Emily Hite

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