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Exploiting Social Networks to Tackle Obesity

Readers of these pages will probably recall the work by Christakis and Fowler demonstrating the “contagious” spread of obesity in a large social network (NEJM 2007).

In a paper appearing in this month’s issue of OBESITY, David Bahr and colleagues from Denver, Colorado, USA, use computer simulation to determine if these findings can be exploited to reverse the obesity epidemic by intervening in social networks.

The paper makes a fascinating read, although the key message is very sobering (despite the rather optimistic interpretation by the authors).

In essence, the simulations suggest that because clusters dominate individual behaviours, once a large cluster of obese individuals has formed it becomes self-sustaining, because an individual in the middle of the cluster (e.g., social network of obese friends) will have a very difficult time sustaining weight loss. The surrounding sea of obesity ensures that even a temporary loss of weight in a few individuals is rapidly reversed, a result that remarkable resembles what is frequently observed in weight loss intervention studies.

Rather than recruiting friends to help with weight loss, the simulations suggest that it may be a better strategy to recruit friends of friends, who help establish contacts to members of other networks.

From a population perspective, one of the more effective strategies could be to target well-connected individuals on the edge of a cluster (i.e., those whose social network contains individuals of more than one BMI cluster). In contrast, targeting poorly connected individuals in a tight network of other obese individuals is likely doomed to failure.

Unfortunately, given the high prevalence of obesity in the US (not so different from that in Canada), the majority of the population already lives in social networks that are obese rather than normal weight. Therefore, finding a critical mass of key “agents of change” will pose challenging, even if the simulations show that these key individuals only have to make up around 1% of the population across BMI ranges.

While all of this sounds great in theory, the paper of course is based on computer simulations – whether or not this knowledge can actually be exploited in real life remains to be seen.

Given my natural skepticism, I am certainly not holding my breath.

Hamilton, Ontario


  1. Makes me wonder if “virtual” social media may have somewhat different dynamics, since they are not confined by the limitations of a physical environment, crossing over to those who may share a goal rather than sharing a geographic location. That may add a healthy diversity.

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  2. Do you think being inside of this community will assist in obtaining funding? 90 % of people feel obesity is laziness, unhealthy living ,weakness ,lifestyle and NO WILLPOWER.
    2,ooo Americans will be diagnosed with Sugar Diabetes on this day. 30,000 U S TODDLERS have got to find social networks that are not OBESE. I am obese and I am fed up with weight bias ,stigma and discrimination ,at the hands of a MEDICAL community . People reach out to me by the hour to say they are fed up as well.
    Shared Accountability will broaden the scope of the issue . I think we need to look at the comminity of food enviroments. Bad Foods are destroying health but it is the obese person that gets all of the negative attention.
    You are most welcomed to visit my web site. You will not be dismissed or EXPLOITED . Just valued ,that might be a new feeling for many.

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  3. In my parents’ day, most – or very many – people smoked.
    Now, most people don’t smoke.
    What changed? People realized smoking was a health hazard.
    It took a lot to fight big tobacco companies and their use of the addictive nature of nicotine to keep people hooked.
    But when people realized the damage caused by smoking they were willing to give up their rituals, their social habits, the comraderie of sharing cigarettes, the sophistication of the smoking shown in films, the association with freedom and machismo or femininity shown in smoking ads, and they even gave up their nicotine addiction.
    Some people still smoke, and get huffy if they meet “discrimination” against their “right” to smoke, but the social norm now is anti-smoking.

    If a social network cluster analysis had been done on smoking decades ago, I’ll bet it would have been similar to today’s obesity clusters, and yet – change happened.

    What worked?
    The health hazards were publicized – very graphically, including photos of damaged lungs, throats, and mouths.
    The alternative was clear – don’t smoke.
    The tobacco companies lost advertising and the ability to manipulate opinion.

    What could work to combat obesity?

    Publicize the health hazards, very graphically – for example all those problems mentioned in yesterday’s blog on Quebec’s program. Use x-rays and mri’s of damaged organs, life expectancy projections, photos of other diseases caused, mobility problems, damaged knees, etc, etc.
    (Just don’t use the usual unflattering photos of obese people which which run in the background of news reports. The people are made to look unattractive and obesity is made to look like a cosmetic problem.)

    Make the alternative clear.
    As you mentioned in a recent blog, doctors in Alberta counsel patients with very complicated obesity problems. A plan to prevent ordinary people from getting fat should be quite possible. The medical people involved in treating obesity in Canada could take the responsibility of making an obesity prevention plan widely known – in fact, make sure it’s everywhere – on tv, in news papers, on line.
    (Following the plan may not be easy, but neither was “stop smoking”, and people did that.)

    Make sure food companies act like food companies (That is, provide food people need to be healthy) instead of tobacco companies (see Weighty Matters blog on how food companies negatively influence the Canada Food Guide)

    If social attitudes and behavior regarding smoking changed, I think there’s hope to change the behavior that makes people obese. People aren’t totally isolated in their own little clusters. If bad outcomes of a behavior are known and graphic, if there’s a clear alternative to avoid those bad outcomes, and if business isn’t allowed to bamboozle people to cover up negative effects of their products, then some people will change, and then the social clusters can start to foster the new behaviors.

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  4. Regarding Ann Hastings’ comment above.
    Smoking is a behavior, which while multi-factoral, is one behavior that can, in most cases, be stopped.
    Obesity is not a behavior. Nor is it even always a series of behaviors. The comparison between smoking and obesity does not work on many levels.
    Obese people already feel discriminated against and stigmatized. Our “larger numbers” have actually not worked to make us feel more socially secure, rather, each obese person is somehow blamed for the obesity epidemic.
    If you want to take a similar tack to the one taken to reduce smoking rates, targeting physical activity with multi-pronged intervetions and campaigns — there is plenty of evidence that being physically inactive at any size, no matter how small, is harmful to health — as well as promoting a healthy diet in a multi-leveled way — will lead to improved health whether or not it results in less obesity. If reducing obesity is your goal — good luck, I believe the unintended consequences will be at least as expensive as doing nothing.
    If improving health is the goal (which I believe it needs to be) then the question is: What can we do to insure the best health of the population, including people who are obese? By focusing on what individuals can change, such as health behaviors, rather than the outcome of obesity, the entire health of the population can be improved. This means devoting resources (time and money) to insuring everyone has access to and time and support for being active and getting a good diet.
    I believe our resources are better used to promote health rather than resorting to scare tactics.
    I know it’s an “n” of one, but I USED to smoke. Desipite being well educated, relatively fit, eating my fruits and vegetables and whole grains, I’m still very fat. I engage in multiple behaviors and avoid many others every day in order to have the best health I can.
    I am in agreement with the idea of holding food companies accountable. I think there needs to be a big shift in the advertising and pricing of foods that don’t contribute to health.
    I don’t know a single obese person who isn’t acutely aware of the health risks associated with being obese. If your target audience is those who are not (yet), I think you would still find a high level of knowledge and attitudes that demonstrate awareness of the risks associated with obesity. People already do select and keep relationships based on size and behaviors.
    I think there is hope to improve health, and I don’t think it comes by making obesity the focus.

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  5. First, congratulations on stopping smoking. I’ve never smoked myself, but Ive seen the gumption it takes for people to quit.
    Second, kudos for being fit and following healthy behaviors.

    Yes, you’re right – smoking is a behavior and obesity is a condition of the body, so my comparison is a bit apples vs oranges.

    It would be more accurate to compare lung disease to obesity, and smoking to the behaviors of improper eating, inactivity, and other possible factors.

    (By obesity, I do not mean just being on the heavy side of the normal weight range, or a bit over that and in need of loosing a couple of pounds for optimal health. One can quibble about what exact BMI or waist circumference or other measure is the cutoff line, however aside from that there is a point a which obesity itself IS a disease, it’s not merely a risk factor for other diseases.)

    I think it is an oxymoron to say one is “healthy and obese”, just as it’s an oxymoron to say one is “healthy and diabetic” or “healthy and has kidney disease”.

    In all of those cases, I think it would be true to say “I have a disease. However, I am doing everything I can to follow healthy practices in my eating, my activities and my lifestyle. I am living as healthy a life as possible while dealing with this diabetes/obesity/kidney disease. I am doing everything I can to prevent this disease from leading to further problems”

    Obesity is a disease. It cripples people. It distorts metabolism. Dealing with obesity means getting medical treatment.
    Just like a diabetic or someone with kidney disease, someone suffering from obesity can’t just follow a normal person’s “healthy diet”. These diseases call for a diet specifically designed for the particular metabolic problems caused by the disease.

    (From my layman’s view: an obesity treatment diet program may include things like: eat a lot fewer calories than normally recommended and do so forever; while loosing weight eat more protein than normally recommended; eat on an exact schedule and each time eat some protein and some carbs; take specific supplements as determined by medical monitoring etc, etc, My point is that a medical diet for obesity is more like a treatment regimen than the way most healthy people eat, and it’s pretty hard to go it alone.)

    The target audience I’d like to see educated isn’t obese people – they need to get medical help. I wouldn’t expect a public health campaign to prescribe a diet for someone on dialysis or an exercise for someone recovering from a bone fracture, and a public health campaign can’t prescribe treatment for obesity. (DIY bariatric surgery, anyone?)

    The target audience would be people of normal weight or close to it.

    The goal would be to prevent those people from getting obesity.

    I’ll accept your contention that most people know about health risks associated with obesity – but I would argue that most people see them as “risks” – long term, possible but not inevitable, vague, and not worth changing a lifestyle for. It took laws and fines to make people wear seat belts because injury was a risk but not certain.

    I don’t think people know that obesity changes metabolism so that loosing excess weight becomes a totally different problem. People think that when they get too fat they’ll just go on another diet and loose the weight. Then they reach their oh-no weight, and it’s too late – their metabolism is shot, they are too big to move enough for significant physical activity, and the weight loss program they thought would solve the problem turns out to be totally ineffective.

    So one goal is to make people aware of the weight version of “Cooked Frog Syndrome”.
    (Put a frog in boiling water and he jumps out; put a frog in cool water, heat it slowly to boiling point and he stays put and gets cooked)
    If a person was struck by a virus that overnight caused his body to bloat to twice its normal size, if he suddenly became incapable of doing many activities and found himself watching from the sidelines, if even basic necessary routines became difficult and exhausting, this would be considered a major medical emergency.
    If the same thing happens over years, the person just slowly lowers expectations of what he can do in life, and he gets cooked.

    You point out that improving physical activity levels and eating healthy diets will improve the health of everybody, including obese people.
    That is certainly a good thing.
    And, if everybody ate a healthy diet and had a healthy activity level, then, if our understanding of weight is correct, (ie it’s determined by diet and activity) then it will be only a matter of time before obesity in the population is practically eliminated – no new cases would occur, even if current cases of obesity were not cured. (There could still be obesity as a side effect of other diseases or of some treatments for other diseases, but those would be comparatively rare.)

    Another goal of a campaign would be to make people aware of calories in food. Sugar is added to all sorts of processed food, fast food puts enough calories in a meal to feed an army, etc etc. The government has given a huge help to people by requiring foods to have nutritional labels – now we need to refine that system to include restaurant meals.
    We need to include calories in the Canada Food Guide as something people need to control. We also need to have people individualize their requirements, as calorie requirements vary amazingly.
    The Canada Food Guide doesn’t help people determine their calorie need (though a little experimenting can figure it out – gain weight -too many calories; loose weight, too few)
    There are too many stealth calories in todays food. Processed and restaurant food can have more or fewer calories than expected, and people can be consuming hundreds more calories than they think they are. Labeling would at least let people know what they’re eating.
    A goal of a public campaign would be to make sure people know about calories, just like people know about vitamin D, for example, including what their personal daily intake should be, and people should be able to use that knowledge because all food should have calorie counts available.

    Food companies often don’t help – consider the TV ad for cheese in which a child won’t eat vegetables unless some “magic” cheese is added. The lessons being taught are: vegetables alone are yucky, and unless you put fat (cheese) on food it’s not good.
    Add some cheese company sales pitch about cheese having calcium, and lots of cheese is sold, and, unless those people eating it count the calories, lots of extra calories are consumed, lots of pounds are gained, and lots of people look at the scales and are dismayed that their healthy choices aren’t so healthy.

    You mentioned overweight and obese people being stigmatized. The implication is “they should have known better than to get fat”. It’s hard to be responsible about eating right when food has been in essence sabotaged with extra fat, and sugar.
    We now are at the point of realizing the effects these products are having on us just as in the 1960’s we realized the effect tobacco was having on us.
    We didn’t have to keep smoking tobacco; we don’t have to keep eating badly.

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  6. Anne Hastings…..excellent point.
    It was when I read an article about diabetes, it convinced me to do something about my Obesity. It is not a cosmetic issue for me. It is kidney failure, blindness, limb amputation, stroke, heart attack issue.

    Dr Sharma and other doctors, are leading the way, it is not healthy to be Obese. But neither is it all the fault of the patient. If the mental part of it is not tackled, we are condemning a generation of people to an early & slow death, not to mention the life unlived.

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  7. Wow! Thank you! I always needed to write on my website something like that. Can I include a fragment of your post to my site?

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