Calories Not Diets
Posted by dlende on March 3, 2009
Have a favorite way to lose weight, one that has worked for you? As long as it involves cutting calories over the long term, then it will probably be effective. That’s the basic lesson from the latest research.
Last week Frank Sacks, a Harvard professor of nutrition, and his colleagues published a major study in the New England Journal of Medicine, Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein and Carbohydrates (full text). A total of 811 participants from Boston and Baton Rouge were divvied up into four diets with different emphases on protein and fat. The participants were then followed over two years. The conclusions, as summarized by Journal Watch, were:
Changes in weight and waist circumference at 6, 12, 18, and 24 months were indistinguishable among groups: At 2 years, only about 15% of each group had lost at least 10% of body weight. Attendance at group counseling sessions strongly predicted successful weight loss.
So there’s the catch! The weight loss was modest. As the Journal Watch title puts it, “Four low-calorie diets yield the same mediocre results. Dieters ate different amounts of protein, fat, and carbohydrate — but, after 2 years, most were still obese.” Still, many people would accept an average loss of 9 pounds and 2 inches less of waistline.
The main implication of this study is that calories matter, not diets. As Frank Sacks emphasized in a great interview on Science Friday, most research on diets has focused on the short-term. But weight loss is a long-term problem – and there calorie restriction is what really adds up. How to achieve that is a major issue, which I considered at length in a previous post on successful weight loss.
In the Science Friday interview Sacks himself ends up advocating a “very common sense approach – to have portion control, to cut out the highest calorie stuff you are eating, and getting some exercise. It’s all an integrated whole.” To that end, Sacks says that individuals should experiment with different diets to see what works for him or her.
On the research side, Sacks bluntly states that “we should move on from trying to figure out which diet is best.” Rather, we should examine why individuals vary so much in their response to weight loss programs. “The difference in individual response just overwhelms any possible dietary difference.”
It was this focus on the individual, not the diet, that struck me most in the New York Times write-up of Sacks et al.’s research, Study Zeroes In on Calories, Not Diet, for Loss. Sacks repeats his individual mantra, “The effect of individual behavior is humongous. We had some people losing 50 pounds and some people gaining five pounds. That’s what we don’t have a clue about. I think in the future, researchers should focus less on the actual diet but on finding what is really the biggest governor of success in these individuals.”
But how do we conceive of the individual? That is a crucial point. The present approach is to focus on willpower and finding the right diet – the lone individual finding the perfect set of techniques. It’s very Western and very Protestant, and bears little relation to how people actually function. Dr Sacks almost gets this, saying that the real question for researchers is, “What are the biological, psychological or social factors that influence whether a person can stick to any diet?”
I say almost, because Sacks still thinks of “factors” as separate from people and as somehow slotting into nice academic categories of biological, psychological and social. It works well for academia, but not in the real world. At least it’s better than popular paleofantasies about the perfect diet, but it doesn’t quite get to the interacting systems and ethnographic realities that play such a role in eating and obesity.
Indeed, Sacks says that while colleagues advocate policy changes, he believes we should try education and displays of calorie counts as a way to deal with obesity in the Science Friday interview. Here he reverts back to a rational individual-perfect technique model, and forgets the lesson from this study – individual variation matters. So education won’t work for everyone. Particularly with eating, education does not address the many social and emotional reasons that people eat, often times more than they are burning (can we say, comfort food!). It also does not address the context of eating – of how culture and inequality shape eating and individual lives.
Here is where I found the accompanying New England Journal of Medicine editorial quite revealing. Martijn Katan goes beyond just discussing the Sacks et al. study in the context of the present literature.
Katan writes, “Thus, even these highly motivated, intelligent participants who were coached by expert professionals could not achieve the weight losses needed to reverse the obesity epidemic. The results would probably have been worse among poor, uneducated subjects. Evidently, individual treatment is powerless against an environment that offers so many high-calorie foods and labor-saving devices. 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.”
Katan proposes a community solution:
A community-based effort to prevent overweight in schoolchildren began in two small towns in France in 2000. 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. This total-community approach is now being extended to 200 towns in Europe, under the name EPODE (Ensemble, prévenons l’obésité des enfants [Together, let's prevent obesity in children]).
A total community approach, with a focus on diets as integrated wholes and individuals as biological, psychological and cultural, would definitely mark a paradigm change. And that’s the kind of paradigm change we want to push here at Neuroanthropology! This point was captured by one caller to Science Friday who said, “Everything we put in our mouths is a part of our diet,” while highlighting a change in lifestyle as the main reason why she recently lost a significant amount of weight.
As one example, the integrated view of lifestyles is one reason that exercise is also not the be-all end-all of the obesity problem. As recent research indicates, level of exercise might not even make a major difference in population-level weight. In his interview, Sacks indicated that exercise played a minor role in weight loss, as it can be difficult to maintain vigorous exercise “day in and day out” and that most people tend to eat back the calories they burn off. But he did say that exercise can play a central role in maintaining a lower weight – 100 calories burned off a day are still a 100 calories burned off.
A range of factors that intersect with a range of individuals will help achieve the overall reduction and maintenance effort. The EPODE program in France does that, as described at length in this piece Thin Living. EPODE achieves success because it is an integrated effort, as Katan described. But outcomes matter as much as efforts. So what is one particular outcome that has made a difference?
Here’s the line that stands out for me, “The results showed that not only had the children acquired a better knowledge of nutrition but they had also significantly modified their eating habits. For example, the number of families that ate chips once a week fell from 56% to 39% (www.epode.fr). Obesity in children did not increase during 1992 to 2000; in the rest of the region, childhood obesity doubled.”
Knowledge, habits, and community effort – sounds like anthropologies in action.