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Obesity

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

Chronic Disease, Health Costs, Health Policy, Nutrition, Obesity, Stanford News

Study shows banning soda purchases using food stamps would reduce obesity and type-2 diabetes

Study shows banning soda purchases using food stamps would reduce obesity and type-2 diabetes

soda

In the late 1800s and early 1900s, carbonated beverages such as Coca-Cola, Dr Pepper and 7UP were sold as nerve tonics and health drinks. But, we now know that sugary sodas contribute to obesity, type-2 diabetes and cavities. Still, most Americans drink more soda than they like to admit.

Even though sugar-laden soft drinks have no nutritional value, they are still eligible for food stamps. Nutrition researchers and some politicians have advocated for a ban on buying sugar-sweetened drinks with food stamps but the U.S. Department of Agriculture, which runs the program, is under tremendous pressure from beverage company lobbyists to keep the existing regulations.

Sugary drinks are especially concerning because too many liquid calories put consumers at a higher risk of developing type-2 diabetes. Some nutrition experts are concerned that taxpayers are subsidizing an unhealthy diet, which will result in higher medical costs for Medicare and Medicaid down the road, when food stamp recipients experience the health problems associated with obesity and diabetes.

In a new study (subscription required) published in this month’s Health Affairs, Sanjay Basu, MD, PhD, an assistant professor of medicine at the Stanford Prevention Research Center, and his colleagues created a computer model to simulate the effects of a soda ban on the health of food stamp recipients. They found that obesity would drop by 1.12 percent for adults, and by 0.41 percent for children, affecting about 281,000 adults and 141,000 children. Type-2 diabetes would also drop by 2.3 percent.

The researchers also calculated the effects of reimbursing participants 30-cents for each dollar spent on fruits and vegetables. The subsidy did not affect obesity or diabetes rates, but doubled the number of people who ate the recommended number of fruits and vegetables each day. A county in Massachusetts tried the same reimbursement system as part of the USDA’s Healthy Incentives pilot study, and saw a similar increase in the fruit and vegetable purchases of food stamp recipients.

“It’s really hard to get people to eat their broccoli,” said Basu in a press release. “You have to make it really cheap, and even then, sometimes people don’t know what to do with it.” But, with one in seven Americans receiving food stamps, he points out that these small changes can have wide-ranging effects.

“It’s very rare that we can reach that many people with one policy change and just one program.”

Patricia Waldron is a science writing intern in the medical school’s Office of Communication & Public Affairs.

Previously: Food stamps and sodas: Stanford pediatrician weighs inCan food stamps help lighten America’s obesity epidemic? and Stanford’s Sanjay Basu named a Top Global Thinker of 2013
Photo by Andy Schultz

Chronic Disease, Health Policy, Nutrition, Obesity, Pediatrics, Videos

Fed Up: A documentary looks for answers about childhood obesity

Fed Up: A documentary looks for answers about childhood obesity

I can’t wait to see Fed Up, a new documentary about childhood obesity.

In the early 2000s, when I was earning a PhD in nutrition at UC Davis, I heard a lot of scientific debate about possible causes of the U.S. obesity epidemic. Was it too much fat in our diets? Too much sugar? Processed food? Junk food ads on TV? An “obesogenic environment” – one in which snacks are ubiquitous, adults drive everywhere and neighborhoods aren’t safe enough for kids to play outside?

Or was it something else?

“The message has been pushed on us: It’s your fault you’re fat,” says Mark Hyman, MD, chair of the Institute for Functional Medicine, in the Fed Up trailer above.

The movie assembles an impressive roster of experts in nutrition research, pediatric health and public advocacy to oppose that message. Michael Pollan, Mark Bittman, Robert Lustig, Marion Nestle, Harvey Karp, former President Bill Clinton and others say we should not be blaming individuals – especially kids – for struggles with their weight. Instead, they are taking a hard look for answers at the food environment.

“This is the first generation of American children expected to lead shorter lives than their parents,” says a voice-over in the Fed Up trailer. That definitely makes untangling the causes of the obesity epidemic worthy of the efforts of our best scientists. Like I said, I can’t wait to see it.

Previously: Childhood obesity a risk for imminent heart problems, research shows, Using hip hop to teach children about healthy habits and Sugar intake, diabetes and kids: Q&A with a pediatric obesity expert
Via Food Politics

Neuroscience, Nutrition, Obesity, Research

Changing views on dietary fiber’s role in weight loss

Changing views on dietary fiber's role in weight loss

food girlAs the brain-gut connection comes into sharper focus, new insights into obesity are emerging. A recent study has found that dietary fiber’s role in weight loss, commonly attributed to releasing appetite-suppressing hormones in the gut, may be a matter of the mind. As Nature News reports, researchers from the UK and Spain showed in a study in mice how a product of fiber fermentation reduced food intake by influencing a region of the brain.

From the piece:

[The researchers] fed mice fibre labelled with carbon-13, which has an additional neutron from the more common carbon-12 that gives its nuclei a magnetic spin and therefore makes it easy to track as it progresses through the body’s chemical reactions. The fibre was fermented as usual into acetate, which turned up not only in the gut, but also in the hypothalamus, a part of the brain known to be involved in regulating appetite. There, the researchers found, it was metabolized through the glutamine-glutamate cycle, which is involved in controlling the release of neurotransmitters associated with appetite control. The same model has been proposed for acetate metabolism after drinking alcohol.

The mice fed with large doses of fermentable fibre ate less food, and ended up weighing less than control mice that were fed unfermentable fibre.

The article notes the researchers plan to investigate enriching fiber with acetate to aid digestion and appetite control. “It’s sort of a way of having your cake, and not eating it,” said Jimmy Bell, PhD, one of the study’s researchers and a biochemist at Imperial College London.

Previously: Examining how microbes may affect mental healthCould gut bacteria play a role in mental health? and Animal study shows a protein in the brain may regulate appetite
Photo by Harmon

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