Do we have to change everything?
From the Rudd Sound Bites blog, an interesting entry on the numerous diet books that have been bestsellers throughout the years. People continually hold out hope that this book, this plan, this guru will have all the answers and so they keep buying diet book after diet book. What prompted this entry though was a link to this editorial by Dr. Martijn Katan. The editorial is ostensibly a response to this study published in the NEJM that found little difference in the efficacy of diets with differing macronutrient compositions (of course, as Dr. Katan points out, in actuality people didn’t manage to stick with their assigned ratios that well.) The editorial doesn’t just address some of the problems with adherence in this particular study though, but the problem of adherence and efficacy in basically all studies of dietary treatment for obesity.
It is obvious by now that weight losses among participants in diet trials will at best average 3 to 4 kg after 2 to 4 years and that they will be less among people who are poor or uneducated, groups that are hit hardest by obesity. We do not need another diet trial; we need a change of paradigm.
Or as the Rudd Blog put it
I’d like to see a book on the NYT best seller list called Throw Away Every Diet Book You Own Because IT’S NOT YOU; It’s Your Environment. There would be chapters on how your workplace, school, neighborhood, and home all contribute to your weight struggles, with challenges such as hidden stairways, omnipresent vending machines, industry-sponsored school events and supplies, televisions everywhere, and more.
This idea in particular is sticking in my brain a bit now due to the fact that I’ve been working on a post about the research into the genetics of obesity. I don’t know if I’ll ever post it*, but one of the interesting outcomes of a lot of research is that genes seem to affect our food choices more than our metabolisms. Or as one paper put it:
While there is widespread acceptance that hereditary factors might predispose to human obesity, it is frequently assumed that such factors would influence metabolic rate or the selective partitioning of excess calories into fat. However, it is notable that, thus far, all monogenic defects causing human obesity actually disrupt hypothalamic pathways and have a profound effect on satiety and food intake. To conclude, the evidence we have to date suggests that the major impact of genes on human obesity is just as likely (or perhaps more likely) to directly impact on hunger, satiety and food intake rather than metabolic rate or nutrient partitioning. At the risk of oversimplification, it seems that from an aetiological/genetic standpoint, human obesity appears less a metabolic than a neuro-behavioural disease.
So the concern is whether or not any dietary intervention can work for more than a small percentage of individuals in an obesogenic environment. Now, to be fair, and without basically copying the entirety of my post on fat and genetics, so far every gene they’ve found to be associated with being fat only has a very small affect – a few kg difference in weight at the very most. For a polygenic trait though it may be that there are many of these small-effect genes or it could be that environment is the ‘trigger’ so to speak, I don’t know.
Both the Rudd Center blog and Dr. Kaplan’s editorial think the solution lies in changing our environment.
From the Rudd Center blog;
..there would also be steps you could take to alter your environment, like making healthy foods most accessible in your home, joining your school’s wellness council to advocate for changes, limiting the number of televisions in your house, lobbying for improved sidewalks in your neighborhood…. Of course some aspects of the environment are a lot easier to change than others, but the point is that diets often fail because of the environmental obstacles that exist. We need environments that support our healthy aspirations, not hinder them. Perhaps if we all redirected our energy from following fad diets to changing our environments, we’d actually get somewhere.
Dr Kaplan points to an effort to curb the increase in overweight children pioneered by a community in France:
Everyone from the mayor to shop owners, schoolteachers, doctors, pharmacists, caterers, restaurant owners, sports associations, the media, scientists, and various branches of town government joined in an effort to encourage children to eat better and move around more. The towns built sporting facilities and playgrounds,
mapped out walking itineraries, and hired sports instructors. Families were offered cooking workshops, and families at risk were offered individual counseling.
Though this was not a formal randomized trial, the results were remarkable. By 2005 the prevalence
of overweight in children had fallen to 8.8%, whereas it had risen to 17.8% in the neighboring comparison towns, in line with the national trend.
I don’t know what I think about any of this. I think improving sidewalks (and neighborhood safety), making fruits and vegetables cheaper, and giving kids ample PE and recess time are good things no matter what their effect on weight happens to be. I hate to think any of these kinds of improvements might be tied to programs whose ‘success’ is measured by decrease in BMI. I also don’t know if this country could ever get away from its fetish for personal responsibility enough to get behind big changes in how we eat and move.
From a personal standpoint though, I do feel like in order to lose weight in a fairly sane and healthy way, I’ve had to change the way I live. Not just add a bit of exercise or eat a little different, but an almost entire paradigm shift in how I move and eat. It’s hard to explain, but the idea that the food and movement environment has to change in order for a lot of people to lose weight really resonated with me.
* I hesitate with any big science posts. I’m not an expert after all** and I’m almost pathologically afraid of not getting something right and giving out wrong information.
**Not that this stops anyone else on the internet from vomiting out all sorts of bullshit when it comes to diet, health and exercise, of course.