At least once a week someone contacts me to tell me that the National Weight Control Registry Proves that long term weight loss is possible for those who “try hard enough”. Let’s take a closer look at the NWCR and these claims of success.
First of all, who started it? Rena Wring, Ph.D who is the Director fo the Weight Control and Diabetes Research Center at the Miriam Hospital and James Hill, Ph.D. who is the Director of the Center for Human Nutrition, and has his own diet program and diet book. To sum up, it was started by people who make their money researching, discussing, and selling weight loss.
What are they? They call themselves “the largest prospective investigation of long-term successful weight loss maintenance.” Let’s look at that:
In order to be a “success” on the registry one must lose 30 pounds – which they consider a “significant amount of weight” regardless of the starting weight of the participant, and keep it off for one year – which they consider a “long period of time.” It’s worth noting that most people gain their weight back in years 2-5, so – following in the footsteps of most studies funded by the diet industry – the NWCR has given themselves a four year efficacy cushion.
How many “successes” do they have? There seems to be some confusion about that. Not only don’t they give an exact figure, but the “Success” page currently says “more than 5,000” while the home page says “over 10,000.” Remember that this is a site that wants us to count on it for research accuracy.
Now let’s get some perspective. Let’s take the high number and round up – we’ll say that they have 11,000 “successes” since 1994 when they started. In order to get a sense of proportion, how many diets have there been since 1994? I found estimates from 45 million to 80 million. Let’s take the lowest number and go with 45 million. So since 1994 that would be 810,000,000 diets. And 11,000 of them have succeeded. A .001% success rate. Now, even if the estimate is off by half and there were only 405,000,000 diets, that is still a .002% success rate.
But wait, you say… That’s not fair since many of those 810 million diets were undertaken by the same people (since dieting hardly ever works long-term.) Fair enough. Let’s say that the exact same 45,000,000 people went on diets every year – so we’ll assume that there have only been 45 million total dieters since 1994. And 11,000 successes. Now we’re up to a whopping .02% success rate. Stop the presses.
So they are studying, at best, .02% of dieters with a four year efficacy cushion to find out how to diet successfully, and then we’re supposed to put our health on the line to mimic them. That’s like studying people who survived skydiving accidents where the parachutes didn’t open and then, armed with that information, jumping out of an airplane with no parachute. Or, statistically, studying powerball winners to see how to become a mulit-millionaire and then, armed with that information, quitting your job to play powerball full time.
Still, for the record let’s look at what they find are the “secrets” to “successful, long-term” weight loss:
- 98% of Registry participants report that they modified their food intake in some way to lose weight.
- 94% increased their physical activity, with the most frequently reported form of activity being walking.
Those who maintain weight loss:
- 78% eat breakfast every day.
- 75% weigh themselves at least once a week.
- 62% watch less than 10 hours of TV per week.
- 90% exercise, on average, about 1 hour per day
My question is this – how many of the between 44,989,000 and 809,989,000 failed dieters did these things as well? How many of those who regained the weight were doing these things? How many fat people do these things? Unless we know that, this information is completely useless. If all powerball players eat breakfast, would eating breakfast make your odds of winning powerball better?
Imagine if I got together everyone who had survived a skydiving accident when their parachute didn’t open and started looking for things they have in common. Even if every single one of them wore a green shirt and had oatmeal for breakfast, it’s ridiculous to suggest that wearing a green shirt and eating oatmeal will allow you to survive a skydiving accident. If it were true, would you sign up for Ragen’s school of skydiving without a parachute, free green shirt and oatmeal with every jump. When your sample is the statistical anomaly your research is useless, and when all you’re looking for is random coincidence among a select group of participants you probably shouldn’t call what you do research at all.
I don’t want to just point out a problem without offering a solutions so I would like to suggest an alternative. First, as always, nobody is required to care about health and health is intensely personal, but for those who are interested in pursuing health: According to a study by the Albert Einstein School of Medicine “51.3% of overweight adults and 31.7% of obese adults were metabolically healthy.’ So I propose we study the 51.3% and 31.7% of metabolically healthy fat people to see if we can find some information about being healthy and fat, rather than study .001% – .02% of “successful dieters” to see if we can figure out how to
jump out of a plane without a parachute make everyone thin (especially since there are no statistically significant studies that show that people who maintain weight loss are healthier.)
Wait – we already have a number of studies that show that healthy habits lead to similar outcomes regardless of weight, remind me why the NWCR has any kind of relevancy at all?
I know that the often repeated 95% failure rate of dieting is controversial and maybe this is why: The National Weight Control Registry would need 2,239,000 (if we go with 45,000,000) or 40,486,600 (if we go with 810,000,000) more success stories just to get to a 5% success rate, and let’s not forget that it is the “LARGEST prospective investigation of long-term successful weight loss maintenance.” and only has, at best, 11,000 successes.
Finally, many of the people in the NWCR who have discussed their lives participate in eating and exercise behavior that qualifies as disordered. So again, this isn’t a train I’m excited about jumping on.
People survive falling from a plane without a parachute, people win powerball, and people succeed at long-term weight loss. But I’m going to wear a parachute, continue working, and not diet – because I’m a fan of math and logic. Of course everyone gets to choose for themselves.
EDIT: I wrote this piece originally on 12/27/12. As of 3/26/14 the WCR is still only claiming to have found 10,000 successes, there have been an estimated 90,000,000+ additional attempts.
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