Friday, 15 June 2012

The National Weight Control Registry: the gold standard in bullcrap (Part 1)

 Whenever anybody talks about the futility of trying to lose weight, somebody like That Awful Woman (TAW), who I won’t give more publicity to by naming, will throw the National Weight Control Registry (NWCR) in their face. See, it IS possible to lose weight and keep it off. This is the proof. You’re obviously just not trying hard enough. But as TAW seems to get all her science from the daily news, she could be forgiven for buying into this myth - it has been carefully crafted to make us believe.

Despite reams and reams of evidence (like this and this and this) showing that NO method of weight loss leads to long-term maintenance, the NWCR continues to be held up like a beacon of virtue, giving hope to all of us failed dieters that lifetime change IS possible. Given the smug condescension with which finger-wagging 'well-wishers', who are apparently just concerned about our health, use the NWCR to belittle and castigate us poor greedy lazy fat people, it is worth looking a bit closer at just what is being touted as evidence of successful dieting. How are these people getting it right when everyone else is failing so miserably?

Well that’s an interesting question. In fact, that’s the very reason the NWCR was set up in the first place. Back in the early 90s, researchers from Brown, Colorado and Pittsburgh universities decided to gather together a database of people who had successfully lost weight and kept it off. The idea was to study these people and find out what their secret was. Not a bad idea, really, particularly since back then we didn’t know as much as we do now about how damaging dieting actually is to your health.

The problems started soon after when they couldn’t actually find any. Well, that’s a bit unfair. They found a few. In a country where over 70 million people are thought to be dieting at any one time, they did managed to attract a few hundred who self-reported that they had lost the required minimum of 30 pounds, and kept it off for at least a year. The first major publication from the NWCR team was based on 784 enrolees who met these criteria. 784. The paper was an analysis of what these people were doing that had helped them to qualify for the registry in the first place. In fact, some had far exceeded the minimum criteria. Average weight loss was 30 kg (66 lbs), and average maintenance was 5 years. It is these particular numbers that are most often bandied about as proof of successful dieting. So let’s look at them a little more closely.

First, that minimum 30 lb weight loss is defined as a weight below their lifetime maximum. So if you lost 100 lbs from your lifetime max, and regained 70 lbs, you’d still qualify. Even if you’d done it numerous times before: 91% had previous ‘failed’ weight loss attempts. The ‘average’ amount of weight lost prior to their current success was 565 lbs. And there was a wide range here, with some losing over 1000 lbs before successfully managing to keep off their current minimum of 30. No information on how long previous weight loss ‘successes’ had been maintained. But enough with the cynicism. What were they doing this time that was different?

 Well, 92% were still monitoring their food intake – counting calories, fat grams and so on. The vast majority maintained a low calorie diet, through whatever means. 95% of men were getting between 1100 and 2300 calories, and for women it was between about 800 and 1800 calories a day. The average was 1700 for men and 1300 for women. About half admitted spending more time and energy thinking about food and weight than they did before. They also  definitely got a lot more exercise, on average, 2830 calories per week, or roughly equivalent to walking 28 miles. Again, the range was big, with some doing up to double this. Most continued to monitor their weight regularly, with 38% continuing to weigh daily, and 7% reporting more than once a day. Now I don’t know about you, but if somebody with a ‘normal’ BMI told me they were thinking about their food and weight a lot of the time, eating just 1500 calories, monitoring every bite of food that went into their mouths, walking over 4 miles and weighing themselves at least once a day, I’d be a bit worried about them.

So that’s how the just under 800 success stories qualified for the NWCR. Even ignoring the well-documented harmful effects of weight cycling (yo-yo dieting), and the somewhat dubious ‘health’ behaviours used to maintain their current weight, let’s just assume that this time really was different. Tune in next time for the not-entirely-surprising results of follow-up studies.


  1. Ahhh in my doctoral program we used to refer to statistics like these as sadistics! Thanks for a great post!

  2. Can't wait for the rest of the series!