Gender-specific differences in obesity
Posted by on August 8, 2011 - 11:24am

Why are some people obese while others are lean? Obese people must make poor eating choices, but could there be a physiological basis for those poor choices? A new study reveals that obese and lean people make decisions about short-term versus long-term rewards differently and have physical differences in their brains. Surprisingly, some of these behavioral and physical differences are found only in women.

An article recently published in the journal Frontiers in Human Neuroscience tested how lean and obese people relate to rewards using a simple card game. In this game, participants had to choose between two decks of cards. One deck provided large immediate rewards but overall losses in the long-term. This deck was meant to parallel the immediate reward of eating and the long-term negative effect of overeating on body weight. The other deck gave subjects smaller immediate rewards but was more advantageous in the long run. This deck represented healthier eating choices – less fulfilling immediately but more beneficial in the long term.

The researchers found that obese women choose immediate rewards more often than lean women. In fact, as the body mass index or BMI of the subjects increased, so did the number of times that they chose from the deck that provided large immediate rewards.

Additionally, as they played this card game over time lean women altered their choices and started to choose more cards from the deck that was advantageous in the long run. In contrast, obese women did not change their decision-making over time and continued to choose just as many cards from the deck that provided large immediate rewards but overall losses as the game progressed.

Remarkably, these behavioral differences between lean and obese participants were limited to women. No difference was seen between lean and obese men.

To investigate the possible basis of the behavioral differences between subjects, the brain structure of lean and obese men and women was examined using magnetic resonance imaging or MRI. Differences in brain structure between obese and lean people have been reported previously. This study found additional differences that were only present in obese versus lean women and not men.

Both the behavior and brain structure of the obese women observed in this study suggest that obese women might make poor eating choices because they are more sensitive to rewards and are driven more by habit-like behavior rather than goal-directed behavior. It is not known, however, if the alterations in brain structure in obese individuals are themselves the cause of obesity and overeating behaviors, or if the alterations are the effect of obesity-related behaviors.

The differences in behavior and brain structure between lean and obese women uncovered in this research could be important for the development of gender-specific treatments for obesity.

 

Can Soda Tax Curb Obesity?
Posted by on July 23, 2011 - 8:14am

To many, a tax on soda is a no-brainer in advancing the nation’s war on obesity. Advocates point to a number of studies in recent years that conclude that sugary drinks have a lot to do with why Americans are getting fatter.   But obese people tend to drink diet sodas, and therefore taxing soft drinks with added sugar or other sweeteners is not a good weapon in combating obesity, according to a new Northwestern University study.

An amendment to Illinois Senate Bill 396 would add a penny an ounce to the cost of most soft drinks with added sugar or sweeteners, including soda, sweet iced tea and coffee drinks. Related to the purpose of the tax, the legislation excludes artificially sweetened and diet sodas.

“After doing the analysis, it really turns out to be the case that obese people like diet soda so much more than regular soda that you can do whatever you want to the price,” said Ketan Patel, a fourth-year doctoral student in economics. “You’re not going to get that much change in obese people’s weight because they already drink diet soda.”

Patel, who recently presented his paper “The Effectiveness of Food Taxes at Affecting Consumption in the Obese: Evaluating Soda Taxes” at a U.S. Department of Agriculture conference on food policy in Washington, D.C., said he initially didn’t know if the diet soda preference was going to be a large factor in evaluating the effectiveness of the soda tax.

“The concern I had was that maybe obese people are less price sensitive,” Patel said. “So if obese people are less price sensitive, then raising the price through a tax will affect their behavior less.”

But that concern became irrelevant since diet drinks are not being considered in the proposed obesity tax.

Beyond its ineffectiveness in reducing obesity, such a tax also would punish consumers that are not overweight or obese, Patel said.

Is there a scenario in which increasing the tax would have an effect on weight? Patel said that could depend on whether people are at a stable weight or whether people are already eating too many calories and therefore their weight will continue to increase. If increasing weights are the status quo, then a tax could prevent people who are currently overweight or normal weight from becoming obese. More research needs to be done on this aspect, however, Patel said.

For this study, Patel used a large data set of sodas price and sales data with individual level data on demographic characteristics and body mass index (BMI) to estimate consumer preferences while allowing for substantial diversity in those preferences. After obtaining estimates of consumer preferences, Patel simulated how a tax would change the choices that consumers make and used the results of the simulation to estimate changes in weight using a weight change model from existing nutrition literature.

In the meantime, however, lawmakers say it does not look likely that the tax will be imposed anytime soon as there is little support for the measure after a recent income tax hike in Illinois.

by Hilary Hurd Anyaso,  law and social sciences editor. Northwestern U.

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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Obesity and Osteoporosis
Posted by on April 21, 2011 - 3:03pm

It has been reported in the past that obesity (body fat mass) is  protective against osteoporosis and fracture.  However, a recent study has documented a high prevalence of obesity in postmenopausal women with fragility fracture.

An international group of researchers has presented research at the European Congress on Osteoporosis & Osteoarthritis that compares the prevalence and location of fractures in obese (Body Mass Index≥30 kg/m2) and non-obese postmenopausal women and examines specific risk factors for fracture.

A history of fracture after age 45 years was observed in 23% of obese and 24% of non-obese women. Nearly one in four postmenopausal women with fractures is obese. The upper arm, ankle and lower leg were significantly more likely to be affected in obese than non-obese women with a prevalent fracture, whereas fractures of the wrist, hip and pelvis were significantly less common than in non-obese women. When compared to non-obese women, obese women with a prevalent fracture were more likely to be current cortisone users, to report early menopause, to report fair or poor general health, to use arms to assist standing from a sitting position, and to report more than two falls in the past year.

The research demonstrates that obese postmenopausal women are almost as likely to fracture as non-obese women, and that poor mobility and increased risk of falls may play an important role. The findings have significant public health implications in view of the rapidly rising numbers of obese people in the population.

 

Eating Addictions Similar to Substance Dependancy
Posted by on April 17, 2011 - 11:16am

Addictive eating behavior and substance dependence have similar patterns of brain activity, finds a new study from the Rudd Center for Food Policy and Obesity at Yale. The study is published in the Archives of General Psychiatry and is the first to link symptoms of addictive eating behavior with specific patterns of brain activity in both obese and lean individuals.

Previous research has identified similar patterns of brain activity in obese and substance-dependent people, which has led to the theory that some people may be addicted to high-calorie foods, but no previous studies have explored whether lean as well as obese individuals who exhibit symptoms of addictive eating behavior have neural responses similar to those of drug addicts.

In the current study, 48 healthy adolescent women ranging from lean to obese completed the Yale Food Addiction Scale (YFAS), which applies the diagnostic criteria for substance dependence to eating behavior. Next, using brain-imaging procedures such as functional magnetic resonance imaging (fMRI), the study examined the relation of food addiction symptoms, as assessed by the YFAS, with the women’s brain activity in response to food-related tasks. The first task looked at how the brain responded to cues signaling the impending delivery of a highly palatable food (chocolate milkshake) versus cues signaling the impending delivery of a tasteless control solution. The second test looked at brain activity during the actual intake of the chocolate milkshake versus the tasteless solution.

Both lean and obese participants with higher food addiction scores showed different brain activity patterns than those with lower food addiction scores. In response to the anticipated receipt of food, participants with higher food addiction scores showed greater activity in parts of the brain responsible for cravings and the motivation to eat, but less activity in the regions responsible for inhibiting urges such as the desire to drink a milkshake. Thus, similar to drug addicts, individuals exhibiting signs of food addiction may struggle with increased cravings and stronger motivations to eat in response to food cues and may feel more out-of-control when eating highly palatable foods.

According to Ashley Gearhardt, clinical psychology doctoral student at Yale University and lead author, “The findings of this study support the theory that compulsive eating may be driven in part by an enhanced anticipation of food rewards and that addicted individuals are more likely to be physiologically, psychologically, and behaviorally reactive to triggers such as advertising. The possibility that food-related cues may trigger pathological properties is of special concern in the current food environment where highly palatable foods are constantly available and heavily marketed.”

The authors assert that efforts to change the current food environment may be critical to successful weight loss and prevention efforts since food cues may take on motivational properties similar to drug cues. The current emphasis on personal responsibility as the reason for increasing obesity rates may have minimal effectiveness as palatable food consumption may be accompanied with a loss-of-control for individuals exhibiting signs of food addiction.

Source:  Yale University

Feel Full on Fewer Calories
Posted by on March 18, 2011 - 8:55am

 

Grapes or Raisins?

Almost everyone who is health conscious agrees that American food portions are out of control!  One of our most visited blogs "Eat less, Move More" has generated a lot of comments and many readers are surprised how small portions need to be if you want to lose weight.   We've also received a number of suggestions like using a smaller plate, eating 5-6  mini meals every day, etc.   But the bottom line remains the same:   If you want to actually lose weight and you are not an exercise buff, portion control is a good way to go. However, not all portions represent the same amount of calories.

Feel fuller on fewer calories. This requires understanding the concept of "energy density".   Energy density is the number of calories (energy) in a certain amount of food.   High energy density means that there are a lot of calories in a small amount of food.   Low energy density means there are few calories in a lot of food.

One of the classic examples is raisins vs. grapes.    A one cup of raisins (dried grapes)  has about 434 calories.  A cup of fresh grapes has about 104 calories.  So to eat the same amount of calories, you would have to limit the raisins to 1/4 a cup!  Which choice would make you feel fuller?   One ounce of potato chips is 150 calories, the same amount of calories found in 3 1/2 cups of air popped popcorn.

In order to lose or maintain your weight, your goal should be to eat more  low energy dense foods.  That way, you eat larger portions that make you feel fuller.   Let's explore this density concept a bit further.   Several factors play a role in what makes food high or low in energy density.

1.  Water.   Fruits and vegetables have a high water content which provides volume but not calories, making them a low energy dense food.  A grapefruit is 90 percent water and a  half grapefruit is only 39 calories.  Watermelon is 92% water.

2. Fiber.  High fiber foods provide volume and take longer to digest, making you feel fuller with less calories.

3.  Fat.  Fat is very high in energy density (remember we are really talking about calories!).   One teaspoon of butter contains almost the same number of calories as 2 cups of low energy dense broccoli.

What about nutrition?   Does  "fullness" translate into a adequate nutritional intake?   What foods are better options when it comes to energy density?.    According to the Mayo Clinic Health Weight Pyramid:.

  • Most vegetables are low in calories but high in volume especially lettuce, asparagus, broccoli and zucchini.    Add more vegetables to your pastas instead of meat and cheesy sauces.   Put veggies on your sandwiches instead cheese slices and gobs of mayonnaise.
  • Fruits are healthy but some are lower calorie choices than others and certain fruits have more concentrated sugars (such as raisins) and have higher calories with less volume.   Fruit juices are also relatively high in calories and don't necessarily fill you up.   Eating a whole orange with its natural fiber will fill you up more than a glass of orange juice.
  • Carbohydrates are either grains or foods made from grains like cereals and pasta.  Select carbs that are higher in fiber like oatmeal, whole grain breads, brown rice and avoid breads made with refined white flour and sweeteners.
  • Fats are a high energy dense food but some are healthier than others.   Watch your portions and include monounsaturated and polyunsaturated fats in your diet like nuts, seeds, healthier vegetable oils (flax see, olive, and safflower oil). Just keep the portions small.
  • Sweets are high in energy density and are a challenge when it comes to caloric intake.   Try to find desserts that have low fat and sugar content, such as fruits and low-fat yogurt.  If they are baked, look for whole grain flour pastries.   The key to limiting the effect of sweets is to keep the servings small (share with your table mates--1 dessert, 4 forks--most restaurants are accommodating).
  • Protein comes from plant and animal sources and the healthiest low-energy dense choices are those high in protein but low in fat  such as lentils (also high in fiber!), skinless white meat, and fish.  Select fat-free dairy foods.

Substituting low density foods keep you from feeling food deprived, make you feel better about your meal and will help keep those calories down!  Here's a final example:   A small order of McD's french fries has 225 calories.  You could substitute (with the same amount of calories)  a salad made with a small apple, 10 cups of fresh spinach, and 1 1/2 cups strawberries with a splash of diet dressing.

Obesity increase Risk of Death
Posted by on December 21, 2010 - 5:11pm

Study Shows Strong Link between Obesity and Mortality

The largest study of its kind has confirmed a strong association between overweight and obesity and an increased risk of death. The study also identified a range of body-mass index (BMI) at which mortality risk is lowest, confirming earlier studies indicating that people who are in the normal weight range have a significantly lower risk of dying from a host of causes compared with those who are overweight. The findings were published December 2 in the New England Journal of Medicine.

Obesity and overweight continue to be major health problems in the United States. Approximately two-thirds of the adult U.S. population are overweight or obese, meaning that they have a BMI of 25 or higher.

Researchers from NCI and other NIH institutes, as well as from other U.S. and foreign health agencies and universities, pooled data on 1.46 million people from 19 long-term prospective cohort studies. The participants in these cohort studies were white and from more industrialized countries, limiting the extent to which the findings can be extrapolated to other populations, the researchers explained. The analysis focused on participants who had never smoked and did not have cardiovascular disease or cancer at study entry, eliminating “potentially strong confounders” of mortality risk that have affected some earlier studies, explained the study’s lead author, Dr. Amy Berrington de Gonzalez of NCI’s Division of Epidemiology and Cancer Genetics.

Overall, the lowest mortality risk was seen for those with a BMI between 20 and 24.9. Above that level, every 5-unit increase in BMI increased the risk of death by 31 percent. The risk of death was substantially elevated in the severely obese, those with a BMI of 40 or higher. Women who fell into this category had a 2.5-fold higher risk of death compared with women in the lowest risk BMI range. The risk relationship was similar for men.

Across the BMI levels that correspond with overweight and obesity, the relationship between BMI and mortality was strongest for participants who were younger than 50 at study entry, Dr. Berrington de Gonzalez added.

Although the cancer-specific mortality risk was smaller than the mortality risk associated with cardiovascular disease, the study only assessed overall cancer risk, she said. “Based on previous studies, we know that the relationship between obesity and cancer varies by cancer type,” she continued. So, while obesity is strongly associated with an increased risk of postmenopausal  breast cancer and renal cancer, for example, it is not associated with some other cancers. As a result, when cancer is considered as a single disease, the overall association is weaker, Dr. Berrington de Gonzalez said.

Why Can't Americans, Be Less Fat?
Posted by on October 7, 2010 - 2:39pm

I just got back from a brief vacation in the Italian region of Emilia Romagna--the land of Parma ham, proscuitto, Pasta Bolognese and tasty hard cheeses. One of the regional specialties is a ravioli filled with spinach and ricotta covered in a butter sauce and sprinkled with parmesan cheese (Are your arteries choking yet?).    I was immediately struck by the lack of overweight people despite these wonderful foods that are high in fat and quite salty.   What is it about Italy that allows people to stay thin, yet eat these rich foods?

Now, I admit that this particular blog posting is not based on comparative research but rather a reflection on a brief vacation experience.   I really don't know if Italians have more heart attacks than Americans---but to the watchful eye, I was struck by all the healthy "looking" people who were strolling the piazzas who were significantly thinner than the people I see walking around the malls in America.  In fact, I saw almost NO overweight people.

Yes, they walk a lot, ride bicycles and spend time walking off their meals during their traditional passegiata (Lots of the men walk with their jackets thrown over their shoulders like a cape....molte elegante!).    But they also eat dinner very late (after 8 pm), close their shops for a 3 hour lunch break, and enjoy their  bread, wine and gelato.  On the other hand, not all meals are large, there are no fast food places in the small towns, and their cups of espresso hold about a tablespoon of caffe in those cute little cups.  Everything is freshly made and the small grocery stores are not lined with freezers filled with processed foods.

We spent some time with friends who lived in the community and learned that they have all their health care covered (even though taxes are high), work about 35 hours max. a week, and have 32 plus days vacation a year which they often spend in neighboring countries hiking and biking.  Many of the pharmacies provide basic health care services locally.    The school children play lots of sports and not everyone has a car.  Trains are plentiful between cities but, in the small towns,  the best way to get around is to walk.    Their houses and apartments are half the size of those in America but very adequate.   Their way of life seems more relaxed---everywhere you looked, people were gathered and simply enjoying each other----and talking to each other!    Cell phones were plentiful  but they didn't seem to replace face to face conversation.    I didn't see people eating at tables and talking on their phones as much as you see here.  They don't seem to watch nearly the amount of TV that Americans do.    I'm sure they have the usual worries about their jobs and families but they still have a quiet zest that permeates their everyday lives.   Overall, the stress level was definitely less apparent than it is in the U.S.    Maybe the word I am looking for is "content".   They seemed happy with their lives whether they were farmers, teachers or stay at home moms.

People say that traveling is educational.  On this trip, I learned that there are lifestyles that may be different---but perhaps better-- than ours.

Menopause and Weight Gain
Posted by on September 13, 2010 - 8:22am

Weight gain during menopause continues to be a challenge to women.  About 30% of women aged 50-59 are not just overweight, but obese.  This weight gain increases one's risk for high blood pressure, heart disease, and diabetes.    Just when we are getting used to the other symptoms often associated with menopause (hot flashes, insomnia, etc), we now have to worry about other serious chronic diseases!   It's hard not to say, "aging is not for sissies".

So why does menopause add those unwanted inches?  Scientists and physicians indicate that it is probably due to a number of factors related to both menopause and aging.

In animal studies, estrogen appears to help regulate body weight.  With lower estrogen levels, lab animals tend to eat more and be less physically active.  Reduced estrogen may also lower metabolic rate (rate at which the body converts stored energy into working energy).  It is possible that the same thing happens to women when their estrogen level drops at menopause.  There is some evidence that estrogen hormone therapy may increase one's resting metabolic rate, slowing weight gain.

Other factors for this weight gain are related to aging.  As we age, we exercise less.  This leads to increased loss of muscle mass, which decreases our resting metabolism even more!  This makes it easier to gain weight.   As we age, our aerobic capacity also declines (the rate we use up energy during exercise). To compensate for this, we may need to increase the amount of time we exercise in order to achieve the same weight loss we experienced while exercising when when we were younger.

To learn more how exercise can help control menopausal weight gain and some tips for ensuring success, click here.

Arthritis Prevalence Higher in Women than Men
Posted by on August 31, 2010 - 10:24am

In 2006, the Center for Disease Control and Prevention (CDC) reported that 21.6% of the US adult population reported arthritis, with significantly higher prevalence in women than in men (24.4% vs. 18.1%). Arthritis prevalence increased with age and was higher among women than men in every age group.    With the aging of the US population, the prevalence of doctor-diagnosed arthritis is expected to increase in the coming decades.   By 2030, it is estimated that 67 million adults age 18 and older will have arthritis, compared with the current 46 million.  Also, by 2030 an estimated 25 million adults will report arthritis-attributable activity limitations.

Functional limitations in routine activities are common among adults with arthrtis:   40% report it is "very difficult" or they "cannot do" at least 1 of 9 important daily functions which include their ability to stoop, bend, grasp, kneel or walk 1/4 mile.  Obesity is a known risk factor for the progression of knee osteoarthritis and possibly of other joints.   Reducing body weight may result in significant improvement in the health-related quality of life of people with arthritis.

Although physical activity and exercise have been shown to benefit people with arthritis by improving pain control, function, and mental health, many people with arthritis report no leisure time physical activity. Low levels of physical activity place individuals with arthritis at further risk of inactivity-associated conditions such as cardiovascular disease, diabetes, obesity, and functional limitations.

Some interesting research is currently taking place at Northwestern U. that is looking at knee alignment and its role in progression of knee osteoarthritis that could lead to earlier and novel interventions that could decrease or prevent arthritic disability in the future.  Many Illinois women who are part of the Illinois Women's Health Registry are participating in those studies.

In the meantime, women (and men) who have arthritis could benefit from keeping their weight down and keeping physically active!!!   As we age, it is even more important that we develop a lifestyle that includes healthy eating and exercise.


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