Tanteterri blogged eloquently about the NWCR, and I thank her for it. But my take is a bit different, because I think that even if they were to release all their data to the public, it would still be useless from either a scientific, public health, or personal health viewpoint. While I think they’re all related, I’ll examine this from the personal health perspective. The hypothetical viewpoint is one of the average fat person, who wants to be healthier and thinks that weight loss is the way to do that.
Let’s say that I’ve been thinking of starting a diet, and I hear about the National Weight Control Registry (NWCR). I check out the site (http://www.nwcr.ws), and look at the Success Stories page. I see all sorts of very familiar phrases: “focus more on health” (duh), “works out an hour each day” (yikes!), “avoids fast food” (double duh), “more fruits and vegetables” (shocking! not really), and so on. The same stuff I’ve seen many times before, and in fact I do some of these things already. Lots of people do these things already, but hardly anyone loses weight and keeps it off. So what makes the Success Stories so special?
I check out the first Research Findings page, and see lots of the same dookie: “eat breakfast”, “watch less TV”, “exercise”, etc. The next page under Research Findings lists 31 papers, from 1997 to 2010. Great! Maybe one of these papers will show me some useful information. These papers echo the same advice in the previous pages, but with specifics that I’ll tackle in a minute. Worse yet, none of them show in any reliable way what the chances of losing weight would be for an average fat American.
It slowly dawns on me that the NWCR is just a cherry picking exercise. Rather than make any attempt at determining the effectiveness of weight loss attempts, it simply tabulates the success stories. The best it can do is to try to come up with “success factors”, such as the not-at-all surprising hints listed above. One hour of exercise isn’t a bad idea, and may even be fun. Eating vegetables is also a great thing to do. And it’s no surprise that some people who do these things have lost weight, but the truth is that lots more folks do these same things and don’t lose much (if any) weight.
See, you can’t really isolate success factors by just looking at successes. You have to look at people who succeed and those who fail and see what makes them different, and see if there is anything that those who can’t lose weight can do differently that will help. The NWCR is a list of people who succeed, because, to get on the list, you have to succeed. And if you regain the weight after you join the registry, it seems like you’re dropped from the list, so that all anyone sees is the successes. This whole mess seems to be make work, and the thrust seems to be more about being some sort of honor roll than an honest attempt to help the fatties.
Many of the commenters on Tanteterri’s post have pointed out that the success stories seem to be obsessed with losing weight, and have structured their lives around that. The papers referenced below (all linked on the second Research Findings page on the NWCR site) confirm this. Specifically, McGuire 1998 concludes that the successful losers consume 1400 calories a day (1700 for men based on another paper) and burn twice that per week in exercise (This is the level of intake that drove men crazy in the World War II-era Ancel Keys study http://www.healthyweight.net/wgtloss1.html#2). Another paper says, essentially, don’t get depression. (I think I’d be depressed if I had to be on half-rations.)
I think that this specific information is buried so deeply because most people would not want to do this. Thus, the useless happy-crappy (as Tanteterri calls it) is in the easy-to-find pages.
BACKGROUND (You don’t have to read this part)
I clicked on the first few papers:
1. Klem 1997: Gives how many lost weight, for how long, and for how much in the NWCR so far, but presents no data on how likely it is for the average fat person to lose weight permanently (5+ years). It simply shows that some people can lose weight.
2. Shick 1998: Shows that very low calorie (and low fat) diets may be needed for permanent weight loss, 1300 calories/day for women and 1700 calories/day for men, less than the famous World War II Ancel Keys study that literally drove men crazy on an 1800 calorie/day (half rations) diet. Not based on NWCR data.
3. McGuire 1998: Reiterates need for very low cal (1400 kcal/day, converted from kJ/day), low fat diet, and high level of exercise (2800 calorie/week expenditure, converted from kJ/week, roughly equivalent to running a marathon every week). Not based on NWCR data.
4. Klem 1998: Based on same NWCR group as Klem 1997, and reports that their weight loss successes do not suffer adverse psychological symptoms. Meaningless for the general population because it’s not a random sample, just cherry-picked success stories. Moody or distressed while on a diet? Your fault!
5. McGuire 1999: Finds that those with unintentional weight loss don’t engage in healthy behaviors, compared to intentional losers. Not based on NWCR data; in fact, based on phone interviews (self-reported information).
6. Wyatt 1999: Based on a sampling of NWCR, shows that weight loss is not always accompanied by a reduction in resting metabolic rate, while admitting that other research says that it usually is.
7. 2nd McGuire 1999: I’ll just quote the last sentence of the abstract: “This study suggests that several years of successful weight maintenance increase the probability of future weight maintenance and that weight regain is due at least in part to failure to maintain behavior changes.” Ya think? Some of the things that the fatties got wrong: depression, binge eating, etc. In other words, shame on you for having mental illness!
8. 3rd McGuire 1999: Again looking at what long term weight losers do differently, concluding that “weight-loss maintainers use more behavioral strategies” and they stick with their diet and exercise regiments. Double duh. Another phone survey not based on NWCR data.