Research

Does The Composition of Your Diet Affect POUNDS LOST?

2012-02-11T13:30:00.001-07:00

The research world has long been trying to figure out whether the protein, carbohydrate, and fat content of a diet matters, or whether it is 'simply' all about the number of calories being taken in, that determines the end effect on weight. While a large clinical trial suggested that the composition of the diet doesn't matter, there may be certain elements of this trial that make it difficult to draw these conclusions.

In the POUNDS LOST trial, originally published in 2009 in the New England Journal of Medicine, over 800 overweight adults were randomly assigned to diets with different proportions of fat, carbs, and protein. At the two year follow up, weight lost was similar in all groups, regardless of the diet composition, leading the authors to conclude that the composition of the diet doesn't matter, and that it's all about the calories.

In a follow up to the POUNDS LOST trial, the authors recently published further data suggesting that there was not only no difference in weight between the various diet groups, but no difference in changes in body composition, abdominal fat, or liver fat lost between the groups either.

In an accompanying editorial in the American Journal of Clinical Nutrition, my colleague Arne Astrup and I comment that further analysis of the POUNDS LOST data show that, based on urine excretion of nitrogen, which is a marker of dietary protein intake, there was actually no difference in protein intake between the low and high protein diet groups. In other words, despite being assigned diets with different protein content, the participants ended up eating the same amount of protein after all. As such, it is not actually possible to assess the effect of protein content on weight loss success based on this study.

The heart of the problem is that it is very difficult for study participants to adhere to a hard and fast dietary regimen for the duration of a study. Although people in this study were asked to eat different amounts of protein, they ended up eating much the same. Much better is to design dietary trials which point participants towards consumption of certain types of foods, without a fixed caloric intake or diet composition assigned. That way, we can study how different types of foods affect weight via their natural effects on hunger and satiety. This is a much more practical way to address the obesity epidemic from a research perspective, as it more accurately represents eating patterns in real life!

drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Photos in Lunch Trays Increase Veggie Consumption in Kids

2012-02-03T13:43:00.001-07:00

While the focus of healthy eating tableware tends to be on limiting portions of carbs and proteins, a study group out of Minnesota took a different slant with a group of kids by putting photos of vegetables in their lunch trays - and it worked!

The study, recently published in the Journal of the American Medical Association, looked at the consumption of carrots and green beans at a school cafeteria, comparing eating patterns on a day with pictures of carrots and green beans placed in the bottom of the tray, to a day when there were no pictures placed in the tray. Kids helped themselves on both days to these vegetables as they wished, and were not aware that their selection or eating patterns were being recorded.

They found that the number of kids who selected green beans more than doubled (from 6.3% to 14.8%), and the number who selected carrots more than tripled (from 11.6% to 36.8%). However, the number of kids choosing these vegetables overall was still low; further, the amount consumed was low, and did not meet government recommendations.

What this study teaches us is that the power of suggestion can have an impact on helping kids make healthier choices, with minimal additional cost above other much more expensive interventions such as structured classroom teaching. While the classroom teaching is a crucial part of teaching our kids to eat healthy, let's not forget that a picture speaks a thousand words!

drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

How You Taste Fat May Be Genetically Determined

2012-01-29T09:05:00.001-07:00

As the human genome is being explored in more detail, the genetic contribution to obesity is becoming increasingly recognized. While we know of at least 45 genes that contribute to obesity, little is understood about how they work. A new study has discovered a gene that affects how we sense and taste fat in our mouths, and postulates that this gene may be one more mechanism that contributes to the development of obesity in people who are genetically prone.

The study, conducted by MY Pepino and colleagues at Washington University, looked at 21 people with obesity and different variants of a gene called the CD36 gene. They found that people who had two copies of a certain variant of the CD36 gene had an 8 fold lower threshold for sensation of fat than people who had no copies of this gene variant. In other words, people with two copies of the gene variant were far more sensitive to the taste of fat than people without this gene variant.

Exactly how these genetic differences affect food intake is not known. It may be, for example, that people who are less sensitive to the taste of fat need to eat more fat to feel satisfied. Further study is needed to understand how the difference in sensitivity to the taste of fat may affect food intake and body weight.

What is increasingly clear is that genetics have a powerful role in the risk of obesity, in the context of the toxic enviroment in which we live.

Note: you can read more about the genetics of obesity here.

drsuetalks@gmail.com

Childhood Obesity and Cardiovascular Risk in Adulthood

2011-11-18T17:45:00.002-07:00

It is well known that obesity in all age groups is associated with increased cardiovascular risk. However, for people who struggle with obesity in childhood but become normal weight in adulthood, it has not been clear whether the risk factors accrued in childhood extends to an increased risk in adulthood. A new study suggests that for these people who achieve a normal body weight in adulthood following childhood obesity, several risk factors for cardiovascular disease are no longer elevated, and are similar to the cardiovascular risk factors of people who were never obese.

The study, published yesterday in the New England Journal of Medicine, analyzed data from over 6,000 people in USA, Australia, and Finland, followed for an average of 23 years. They evaluated several cardiovascular risk factors, including cholesterol profiles, blood pressure, presence of diabetes, and thickness of the wall of the carotid artery (which is a marker for cardiovascular disease), and looked at how these risk factors varied depending on whether individuals were overweight or obese in childhood and/or adulthood.

They found that for people who were obese in childhood and adulthood, the risk of having each of these risk factors for heart disease was several fold higher than for people who were normal weight in childhood and in adulthood.

Importantly, they also found that for people who were obese in childhood but normal body weight in adulthood, their risk factors in adulthood were no different than for people who were never obese.

While the ideal management of childhood obesity is prevention on a societal level, the treatment of obesity in childhood is clearly crucial as well. This study lends strong support to the importance of treating childhood obesity, as improving body weight towards a normal BMI reduces cardiovascular risk.

Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Follow me on Facebook: drsue.ca

Genetics Influence Response of Body Weight to Gastric Bypass Surgery

2011-10-15T13:12:00.002-06:00

Gastric bypass surgery is an increasingly utilized treatment option for severe obesity worldwide. While this surgery can be very successful to result in substantial and sustained weight loss over the long term, individual results from person to person are highly variable. A recent study suggests that a person's genetics may be the primary factor responsible for this variation.

The study, just published in the Journal of Endocrinology and Metabolism by Ida Hatoum and colleagues, examined the DNA of 848 patients undergoing gastric bypass surgery at the Massachusetts General Hospital. Amongst these patients were 13 pairs of first degree relatives, none of whom were living together. An additional 10 pairs of patients were identified who were living together but not related (thus allowing a comparison of the effect of environment on the efficacy of surgery). The remaining 794 people in the study were randomly paired for a non-genetic, non-environmentally connected comparison group.

Interestingly, the study found that first degree relatives had a similar response to surgery, with an average of only 9% difference in the excess weight lost between members of each pair. In contrast, there was a 26% difference in excess weight lost between cohabitating, unrelated individuals, which was no more similar than unrelated randomly paired individuals, who had a 25% difference in excess weight.

These results suggest that genetics have a strong influence on the effect of gastric bypass surgery on body weight. Interestingly, they also suggest that the home environment does not have an influence on the efficacy of gastric bypass surgery.

We are certainly becoming increasingly aware of the strong genetic influence in obesity. Dozens of genes which contribute to obesity risk have been identified so far, and this number continues to climb as our knowledge base grows. It is therefore perhaps unsurprising to learn that genetics play a strong part in the response to bariatric (weight loss) surgery as well.

The current study examines the influence of genetics on the lowest weight reached (called the 'nadir') after gastric bypass. I would be very interested to know if genetics has an equally strong influence on the risk of weight regain after hitting the nadir weight postoperatively, as there is also quite a substantial variation in weight maintenance vs weight regain in the long run after bariatric surgery. More study is needed in this area.

Although this study was too small to be able to identify the specific genetic contributors to weight loss success after gastric bypass surgery, larger scale studies could be undertaken to examine the entire human genome to try to identify the relevant genes. It is likely that there are many genes involved here, and their interactions are likely to be extremely complex. Discovery of new genetic mechanisms involved in the response to surgery may teach us something not only about surgery but about obesity in general, possibly leading us down the path to other discoveries that will assist us in non-surgical treatment of obesity as well.

As for people currently contemplating gastric bypass surgery, this study is too small to make definitive conclusions, but if you have a first degree relative (parent, sibling, or child) who has had the surgery, the success they experienced may be predictive of your own.

Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Follow me on Facebook: drsue.ca

Video Blog - Highlights from American Obesity Society Conference

2011-10-07T16:30:00.000-06:00

In this video blog, Dr Sue discusses just a few of the many highlights from this week's Obesity Society meeting in Orlando, Florida.

Some of the highlights include:

1. A focus on learning more about the genetics of obesity;

2. Food Reward: Do differences in how we desire, and how we enjoy, food, affect our risk of weight gain?

3. Lifestyle interventions: a focus on building environments that are conducive to more exercise and healthy eating

4. Medications: nothing new currently, but many interesting possibilities on the horizon...

5. Bariatric surgery: more data on longterm success rates, and novel technologies being studied.

Watch to learn more!

Follow me on Twitter for more tips! drsuepedersen

Follow me on Facebook: drsue.ca

Chemicals In Our Environment that Contribute to Obesity

2011-09-24T07:46:00.000-06:00

It's no secret that the environment we live in is a major contributor to the obesity endemic, for several reasons: oversized portions, easy accessibility of unhealthy food choices, motorized transport, just to name a few. Another important aspect to add to this list is a host of chemicals in our daily environment, for which there is mounting evidence linking them to the risk of obesity.

These substances, collectively referred to as 'endocrine disrupting chemicals', are synthetic substances that are widely used in production of products that are present in our daily environment, which may have an effect on the synthesis or function of our hormones when we are exposed to these agents. We become exposed to these chemicals through inhalation of polluted air, food or water contamination, or by absorption through the skin.

As recently summarized in the journal Obesity Reviews by JL Tang-Péronard and colleagues, a link has been drawn between obesity and a number of these agents. Just to give a couple of examples (there is a much more extensive list and discussion in the referenced article):

Dichlorodiphenyldichloroethylene (DDE) has perhaps one of the strongest links with obesity. It is the main metabolite of DDT, and was used as an insecticide before its prohibition in the 1970's and 80's. Not only has DDE exposure been shown to be associated with obesity, it has also been demonstrated that exposure to a fetus before birth increases the risk of obesity later in life (eg, in childhood or puberty).

Polychlorinated biphenyls (PCBs) were used in many electrical appliances prior to being banned decades ago, but they are still found in the environment and in humans as well. Some PCBs have been found to either activate or inhibit our steroid hormone receptors, and some have been shown to stimulate specific metabolic pathways. PCB exposure has been shown to be associated with obesity in some studies, and appears to vary depending on timing and dose of exposure. PCBs may also have a bigger impact on weight development among girls than boys.

Bisphenol A, which is used in the production of epoxy resins and polycarbonate plastics and found in products ranging from contact lenses to water bottles to DVDs to dental sealants, has been linked to an increased risk of diabetes, metabolic syndrome, polycystic ovary syndrome, and cancer, and may increase the risk of obesity and excess body fat as well.

Other agents found in everything from flame retardants to burning coal tar to plastics, from children's toys to food packaging materials, have also been suggested to increase the risk of obesity.

Not only may some of these agent contribute to the risk of obesity, but they may also make it harder for a person to keep weight off following weight loss. Some of these compounds (called 'organochlorines') are actually stored away in fat tissue, and may leech out into the circulation as weight is lost. Increases in plasma organochlorine levels found during weight loss have been shown to decrease energy expenditure, potentially via a decrease in thyroid hormone levels.

So, what can we do to minimize our exposure to these agents? Given that many of these agents are so widely used, restriction in many cases will have to come from governmental agencies (as has already been done in the case of several of the chemicals listed above). We can take simple steps ourselves, such as:

avoiding food and drink containers that contain bisphenol A (particularly avoid microwaving them, as this releases the BPA into your food)
minimizing use of perfumes and scented deoderants and aftershave (which often contain phthalates, another endocrine disrupting chemical that has been linked to obesity risk);
researching the toys we buy for our children.

Through promotion of public policy and awareness, taking our government to task as research reveals more information to us, and keeping as informed as we possibly can about how to minimize our exposure, hopefully we can all work together to minimize our society's exposure to these agents.

Follow me on Twitter for more tips! drsuepedersen

Follow me on Facebook: drsue.ca

Does the weight of those you eat with influence your diet?

2011-08-13T14:50:00.000-06:00

An interesting study in the Journal of Consumer Research says yes - the way in which others heap (or don't heap) up their plates can affect the eating habits of those eating with them.

In this study from the University of British Columbia, a study participant (who did not know the intent of the study, and thought they were participating in a study of movie viewing) was paired up with a researcher who was thin on one visit, and disguised wearing a 'fat suit' on a second visit. Each pair was offered a snack of granola or M&Ms.

In the first round of study, the thin researcher went first, and took a big helping of the snack. Participants were found to heap their own plates in response, taking even more food than they did when they were in the room alone. When the researcher dressed up in a fat suit and took a large helping, the study volunteers took a smaller amount of food, though they still took more than when they were alone.

In the second round of study, the thin researcher took a tiny amount of food; the result was that study volunteers cut down on their own portions. When the obese researcher took only a little food, study participants indulged a little more.

So what is the psychology behind these findings?

1. When we see thin people taking large helpings, it may provide some (false) reassurance that it is OK to heap up too. The thinking is that if they can do it and stay thin, then it must be ok. What is not seen, however, is what that thin person is eating for the rest of the day, nor what they are doing for physical activity to burn off the excess calories.

2. When we see an obese person taking a large helping, an association is drawn between that person's obesity and their excess caloric intake, which may motivate others around them to scale back their own eating, so as not to gain weight with extra calories themselves.

3. When a thin person takes a small helping, an association is again drawn between that person's appropriate weight and appropriate intake, encouraging others to do the same. When the overweight person takes a small helping, however, the perception is that that person must be on a diet, and if someone around them is not on a diet themselves, the subconscious conclusion may be that it is OK to take a little more on their own plates.

The solution? Don't let other people's eating habits influence your own; remember that when you are meeting someone and eating together over a one hour lunch, that is only a snapshot, and not necessarily representative of what that person is doing or eating for the rest of the day. Stay true to your goals, and what you know you need to do in order to accomplish them!

Dr. Sue © 2011 www.drsue.ca drsuetalks@gmail.com

Chatelaine Interview: The Latest News and Research in Obesity

2011-08-06T08:50:00.000-06:00

A few months ago, I was asked to provide an overview of the undertakings at this year's Canadian Obesity Summit in Montreal, by James Fell, fitness columnist, certified strength and conditioning specialist, and the man behind Body For Wife.

The complete article can be found at this link. Below are some excerpts regarding elements of the Summit that I felt were important to highlight. As some very controversial issues were raised and discussed, I thought I would post these items, and I'd really like to survey my readers as to their thoughts on these issues! Please feel free to post a comment by clicking on the envelope icon at the bottom of this post - this is how we can get a good dialogue going, and stimulate change in our society!

1. Genetics: “There are least 45 obesity-related genes that have been discovered and each one contributes 2-3kg to body weight. We don’t understand a lot about how they work; some create a different balance in hunger hormones and others cause fat storage. It’s not that some people are genetically fixed to be obese, but it can set the stage.”

Dr. Pedersen also mentioned how a woman who is obese while pregnant increases the prevalence of the child being obese through epigenetic changes that take place in utero.

2. Environment: “There was a lot at the conference about guiding Canadians to lead healthier lives. For example, should there be a junk food tax? Can we create programs to get Canadians to focus on weight loss and healthy eating and getting more exercise?”

3. Childhood obesity: “Eight percent of Canadian adolescents are obese, so how do we create good family-based programs to help them lose weight? These have to be focused on the parents because if they lose weight, then the kids lose weight by default.”

Sue also had some interesting comments about adolescents and bariatic surgery. “Lap banding is favoured in kids [in extreme cases where it is deemed necessary] because it is the least invasive and is reversible. The Hospital for Sick Children in Toronto is the only place in Canada that is doing it right now. The decisions for bariatric surgery with children are very challenging.”

4. Adult obesity management: “There was a big focus on weight-loss surgery for people with Type 2 diabetes because the surgery can put it into remission. Having the surgery is done when the benefits of it outweigh the risks. Bariatric surgery can be the appropriate decision for a patient who has failed in all other attempts to lose weight.” Dr. Pedersen stated that such patients require psychological counseling as well, and that this is never a decision to be entered into lightly.

In regards to bariatric surgery, there is not enough funding so the wait list is about five years. Some provinces allow people to pay for it themselves, allowing lap banding for about $16-20 thousand for those who don’t want to wait.

Dr. Sue © 2011 www.drsue.ca drsuetalks@gmail.com

Follow me on Twitter for more tips! drsuepedersen

Follow me on Facebook: drsue.ca

Can Decreasing Food Variety Help Control How Much We Eat?

2011-07-31T12:05:00.002-06:00

We all know it to be true: by day 2 or 3 of eating the same leftovers, most of us are good and tired of that meal and ready to enjoy something new. Most of us look for different things to eat each day, to enjoy a constantly changing taste sensation. Perhaps we should not be too quick to switch up our meals, as research suggests that eating in a more repetitive pattern may be beneficial in controlling our food intake.

A recent study tested the difference in food intake patterns in a group of women served macaroni and cheese every day for 5 days, versus once a week for 5 weeks. They found that the women who received the meal once a week ate about the same amount each week, whereas those who received it every day had a gradual decline in the number of calories they consumed. These results were consistent for subgroups of both obese and non obese women.

Thus, it appears that eating in a more repetitive fashion may be beneficial for prevention of weight gain and as a weight loss strategy as well. As discussed in an accompanying editorial to the article, public health policy planners and school lunch menu planners should take this information into careful consideration - a plethora of variety on the menu may not be a virtue.

Of course, eating the same meals every day would be detrimental if there is not enough variety, as a varied food intake is crucial in ensuring that we obtain all of our necessary vitamins and minerals. Consider a strategy such as this: If you were planning to make seven different dinner meals in a week and you were planning to repeat this menu each week for a month, consider instead eating the same meal for four days in a row, then switching to the next one (you may need to re-cook the same meal to ensure your food is fresh). This would also simplify the grocery shopping!

I'm interested to hear what my readers think!

Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Can Watching TV Kill You?

2011-06-18T18:22:00.001-06:00

That may sound a little melodramatic, but this is what recent research suggests, bluntly put: watching TV for more than 2 hours per day is linked with an increased risk of death.

TV watching is the number one sedentary activity of our time. Sixty percent of American adults watch TV for more than two hours per day on average, with a slightly lower number of hours logged for our western european counterparts.

Several studies have examined the association between TV watching and risk of diabetes, heart disease, or death. The data from several of these studies was recently brought together in a meta analysis by Grøntved and colleagues in the Journal of the American Medical Association. Upon evaluation of all prospective cohort studies in this area in the last four decades, they found that over 7-8 years of follow up, watching TV for two hours per day is associated with:

a 20% increased risk of getting type 2 diabetes;
a 15% increased risk of cardiovascular disease;
and a 13% increased risk of death.

Put another way, for every 2 hours of TV watched daily, the authors found that per 100,000 people, there would be 176 cases of type 2 diabetes and 104 deaths per year. For mortality (death) risk, they found the risk really started to accelerate above 3 hours per day of TV watching.

It may not seem like rocket science that a sedentary activity like TV watching is associated with increased risk, but it turns out that the relationship is much more complex than that. As blogged previously, as many as 25% of the day's calories are consumed in front of the tube, and TV watching results in a preference for calorie laden foods (advertising may be partly to blame here). In addition, emotion, adrenaline, and/or stress generated from watching your favorite, riveting TV program, may result in increased hunger as well.

It is more clear than ever before: let's work to keep our tube time to a minimum and spend the time being active instead!

Dr Sue

www.drsue.ca © 2011 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Eat Breakfast - And Make it High Protein!

2011-05-28T08:01:00.000-06:00

We have long extolled the virtues of eating breakfast as an important weight loss and weight maintenance strategy: we often counsel patients to 'eat breakfast like a king, lunch like a prince, and dinner like a pauper'. A recent study gives us more insight as to just how eating breakfast affects our brain activity and helps us control weight - especially if we load it up with a good dose of protein!

Heather Leidy and colleagues looked at the effects of breakfast eating in overweight, breakfast-skipping adolescent girls. Ten girls were provided a normal protein (18g) and a high protein (50g) breakfast (each containing 490 calories) for a week each, and their appetite, feelings of fullness, and brain activation responses (using functional MRI scans) were compared to their baseline values in their usual breakfast-skipping habits.

The study found that the addition of breakfast resulted in significant reductions in brain activation responses to food stimuli several hours later, in areas of the brain that are associated with hunger, desire to eat, food motivation, and reward. Decreased brain activation in these areas (including the hippocampus, amygdala, and others) were associated with lower appetite scores and higher sense of fullness as ranked by study participants.

In addition, the high protein breakfast led to even lower activation in some of these important food intake regulating areas of the brain, compared to the normal protein breakfast.

Therefore, this study shows that eating breakfast may help to regulate brain activity to control eating behaviours later in the day, especially if the breakfast is high in protein.

So, get out your Egg Beaters, your no-salt-added cottage cheese, your skim milk, and your lean cuts of deli meat - there are lots of options to create a high protein, healthy start to your day!

(Please note that if you have any kidney problems, that you should speak with your doctor about how much protein in your diet is right for you, before making changes to the protein in your diet.)

Dr. Sue © 2011 www.drsue.ca drsuetalks@gmail.com

Follow me on Twitter for more tips! drsuepedersen

Follow me on Facebook: drsue.ca

ERGEM: Gastric Bypass Research Study

2009-10-15T03:19:00.000-06:00

I was interviewed this week by the Danish Heart Institute, regarding a research study I have put together with colleagues at the Department of Nutrition, University of Copenhagen this year. It's called the ERGEM study: Effect of Roux en y Gastric bypass on Energy Metabolism.

You can also read about our study on www.clinicaltrials.gov.

More to come about this study on this site www.drsue.ca - stay tuned!!

Dr. Sue © 2009 www.drsue.ca / drsuetalks@gmail.com

2009-04-29T11:06:00.002-06:00

Dr. Sue is passionate about the pursuit of knowledge, and as such, she is actively involved in the world of medical research. In fact, she is currently on a research sabattical at the University of Copenhagen, Denmark, where she is involved in trials of weight loss medication, and studies of the relationship between poor sleep and obesity. In addition, she is currently writing two large study protocols, designed to gain a better understanding of the dramatic weight loss seen following gastric bypass surgery.

Peer reviewed medical publications include:

Pedersen S, Kang J, Kline G. Portion control plate for weight loss in obese patients with type 2 diabetes mellitus: a controlled clinical trial. Archives of Internal Medicine 2007 Jun 25; 167(12) 1277-83.
Comment in: ACP Journal Club 2007 Nov-Dec 147(3):68.
Pedersen S, Brar S, Faris P, and Corenblum B. A validated questionnaire for use in the diagnosis of polycystic ovary syndrome. Canadian Family Physician 2007 June; 53:1041-47.
Pedersen, SD., and Wong, N. Dyslipidemia: when, why, and how to treat. Parkhurst Exchange 2003; 11(11):113-19.
Pedersen, SD, Dewey D, and Parsons H. Stress levels experienced by parents of enterally fed children. Child Care Health Devel 2004; 30(5):507-13.

Dr. Sue also serves as peer reviewer of potential original research publications for the following medical journals:

The Journal of Clinical Endocrinology & Metabolism
British Medical Journal
International Journal of Obesity
The Scandinavian Journal of Clinical & Laboratory Investigation
Student British Medical Journal