The US National Weight Control Registry (NWCR) is an ongoing registry of individuals successful at maintaining weight loss. Participation is voluntary and individuals have to have maintaine a weight loss of at least 13.6 kg (30 lb) for a minimum of 1 year to qualify.
Registrants are invited annually to respond to a battery of questionnaires in which they self-report various aspects of their lifestyle and health conditions.
In a recent paper in OBESITY, Lorraine Ogden and colleagues from the University of Colorado, present the results of a multivariate latent class cluster analysis in an attempt to identify unique clusters of individuals within the NWCR with regard to their experiences, strategies, and attitudes with respect to weight loss and weight loss maintenance.
Based on the analyses of 2,228 participants enrolled between 1998 and 2002, the researchers found four distinct clusters:
Cluster 1 (50.5%): represents a weight-stable, healthy, exercise conscious group who are very satisfied with their current weight.
Cluster 2 (26.9%): has continuously struggled with weight since childhood; they rely on the greatest number of resources and strategies to lose and maintain weight, and report higher levels of stress and depression.
Cluster 3 (12.7%): represents a group successful at weight reduction on the first attempt; they were least likely to be overweight as children, are maintaining the longest duration of weight loss, and report the least difficulty maintaining weight.
Cluster 4 (9.9%): represents a group less likely to use exercise to control weight; they tend to be older, eat fewer meals, and report more health problems.
So what can we learn from this analysis?
As a clinician, I don’t worry about Cluster 1 too much – these folks are healthy, exercise conscious, and apparently happy – they seem to be at their ‘best weight’ – good for them!
I am also less concerned about Cluster 3 – they apparently had no problem losing weight (which they mostly gained as adults) and don’t seem to have a big problem keeping it off. Unfortunately, they are only about a tenth of the folks in the NWCR, but nevertheless, good for them too! Like those in Cluster 1, they’ve achieved their ‘best weight’.
The people I do worry about, however, are the folks in Clusters 2 and 4. Together, they make up almost 40% of the maintainers, but are clearly struggling, using a lot of support, and have more mental or medical problems – these are the folks who, by definition, are now probably below their ‘best weight’.
But what else can we learn from these findings? Unfortunately, not much.
This is because the study largely tells us ‘what’ people are doing and not ‘why’ they do what they do.
So yes, some people who are healthy, exercise conscious, and generally happy can keep their weight off. But the question really is how or why they become exercise conscious and what exactly makes them happy. Only if I understand the answer to those two questions will I have found a strategy that may work for others – it is probably not simply enough to tell everyone to become exercise conscious and happy (and also, it helps if you happen to be healthy!).
Does it help me to know that even if you don’t exercise and happen to be depressed, you can still keep weight off, but you’ll require a lot of support and may end up quite stressed about it? Perhaps.
Or, if you’re older and have more health problems, your best bet is to simply eat fewer meals? (Now I worry)
While this information may be helpful in a conceptual sort of way, what is really lacking is any insight into the actual biology of what is going on.
Do successful weight maintainers have different genes, less leptin suppression, a less active hedonic system, a lesser starvation response, or simply a more active prefrontal cortex?
What I really want to know is how the biology and/or psychology of ‘maintainers’ differs from that of most people?
Or do they simply have more time on their hands and better support systems and biology doesn’t really matter?
As I’ve said before – studying the ‘whats’ is nice but what we really need to understand are the ‘whys’.
Ogden LG, Stroebele N, Wyatt HR, Catenacci VA, Peters JC, Stuht J, Wing RR, & Hill JO (2012). Cluster analysis of the National Weight Control Registry to identify distinct subgroups maintaining successful weight loss. Obesity (Silver Spring, Md.) PMID: 22469954