Unpacking the National WEight Control Registry

The Myth of Lasting Weight Loss

Whenever I state that weight loss is unsustainable, I find myself prefacing it with, “for the vast majority of people.” Because there’s always someone who brings up an anecdote—maybe a sister’s roommate’s mother-in-law who lost 50 pounds and kept it off for 20 years.

It goes without saying. that there is no such thing as absolutes when it comes to the human body. Yes, exceptions exist, but they’re rare, and they don’t negate the fact that weight loss is generally unsustainable for most.

Over the years, several of my harshest critics mention the National Weight Control Registry (NWCR) as a counterpoint. For those that don’t know, this is a registry of more than 10,000 people who’ve lost a significant amount of weight and allegedly kept it off.

The registry was established in 1993 by researchers Rena Wing and James O’Hill, and it relies entirely on self-reported data. Participants join by filling out a form on the website. Before you ask, there is no cost to join the registry and neither is compensation provided.

If you think you’re eligible, you are asked to fill out questionnaires about how much weight you’ve lost, weight-maintenance behaviors, and other factors. This is followed by annual questionnaires. To be clear, no one actually follows up with participants in person.

Bias and Limitations of the National Weight Control Registry

There is only one medical doctor attached to the NWCR team. Holly R. Wyatt, M.D, is Assistant Professor in the Endocrinology department at the University of Colorado and Denver Health Sciences Center.

At the time of publishing, Dr Wyatt has received funding from the weight-loss drug company Novo Nordisk to the tune of $662,000 since 2018 according to Open Payments Data. This brings up questions about bias in the registry, as financial ties to the weight-loss industry might influence the way its data is interpreted. Since Open Paments Data is only available for healthcare providers as opposed to all researchers, it has not been possible to investigate this further.

The registry data has some clear limitations. For starters, it’s overwhelmingly white (about 95%) and mostly female (80%), which isn’t representative of the general population it serves. Plus, most of the data is self-reported, so people could be overestimating or underestimating their weight changes depending on what they remember or how they feel.

The registry also requires participants to have lost at least 30 pounds, and claims that the average weight loss maintained is about 66 pounds for an average of five and a half years. However this is based on the participatn’s reported “highest weight” as opposed to the weight they are when joining the registry.

One of the big issues with interpreting the registry data is that it includes a broad range of weight-loss maintenance times, from one year to as long as 66 years. We know that short-term maintenance is easier, so it’s not clear how many participants maintained weight loss for just a year or two before regaining it. This makes it hard to draw conclusions about what “long-term” weight loss really looks like.

When Disordered Eating Becomes 'Weight Maintenance'

Research based on the NWCR also highlights some potentially harmful behaviors. A 2001 study found that people who maintain weight loss long-term tend to follow low-fat diets (common advice back then), weigh themselves frequently, and keep track of their food intake. They also engage in very high levels of physical activity—well beyond typical health guidelines.

These behaviors overlap with typical characteristics of disordered eating, but in the context of the registry, they’re framed as positive. This raises some ethical concerns. When a thin person weighs themselves regularly, keeps track of everything they are eating, and exercises religiously, we start to worry. Doctors call these behaviours red flags.

Yet when a Fat person does it, it’s called “weight maintenance” and we’re no longer concerned about the consequences. According to the website, 90% of registry participants report exercising around an hour per day, which far exceeds general health guidelines of 150-180 minutes per week.

This level of exercise is closer to over-exercising, which has been associated with health risks like high blood pressure, cardiac remodeling, sudden cardiac death, and atrial fibrillation. There is also no mention of the psychological or social consequences of these types of behaviour.

Now, the registry does show that the longer people maintain weight loss, the easier it becomes to sustain. However, even within the registry, weight regain is common. In a 2003 prospective study of 2,400 registry participants, two-thirds regained weight within the first year. Only 11% of them managed to get back to baseline by the end of the two year study.

Those who regained at least 5% of their weight were classified as “relapsers.” Among those who relapsed, only 5% managed to get back to their lowest weight by the second year. suggesting that even in this supposedly “successful” group, regain is frequent.

The authors of the study do not believe that these  findings should “over-shadow the overall success of the participants in this sample.” But if two thirds of participants were weight restoring over a two-year period back in 2003, I’m curious to know where they are now.

Two Clusters, Two Realities: A Genetic and Social Divide

Another interesting study from 2012 analysed NWCR participants by clusters. The first group, labelled “typical” NWCR participants, included mostly white, well-educated, married individuals who did not experience fatness until adulthood.

The second group, which struggled more with weight cycling and poorer health, was more representative of the broader fat community: they often experienced fatness from a young age, came from families with at least one fat parent, and had a higher lifetime BMI.

There were almost twice as many participants in cluster one than there were in cluster two, and I can’t say this came as much of a surprise. Only half of those in cluster one had at least one Fat parent, as opposed to two thirds in cluster two. Since weight has a strong genetic component (up to 70% heritability), it is not surprising that those who struggle the most are fighting their genetics. Hence fewer are included in the registry.

Then there’s weight cycling, a topic I will be returning to over and over again in my No Weigh Program and book. Since three quarter of Cluster 2 were considered Fat by the time they finished school, it is reasonable to assume that they started dieting at an earlier age. Since weight cycling is highly predictive of long term weight gain, it stands to reason that this group would struggle to maintain weight loss.

In summary, the NWCR’s data are limited, outdated, and often flawed, with only a few studies published in the last decade. The registry’s composition is narrow, largely representing white, well-educated, higher-income individuals, which does not reflect the wider Fat community.

The reliance on self-reported data and the lack of transparency makes it hard to gauge the true effectiveness and sustainability of the weight loss experiences represented. The NWCR might be celebrated in some circles, but its findings, context, and limitations raise questions worth considering.

For further analysis and critique of the NWCR, check out this article published in 2005 by a group of health-at-every-size (HAES) professionals.

Two Clusters, Two Realities: A Genetic and Social Divide

 

The NWCR’s data may offer a glimpse into the experiences of a select group of people, but its limitations are glaring.  Its findings often perpetuate harmful narratives about weight loss, ignoring the broader picture and the well-documented risks of disordered behaviors.

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