Friday, January 29, 2016

Rate of weight loss is not a good predictor of long term success

The Problem of Obesity:  Personal efforts to combat it

Rate of weight loss and its relationship to long term success

Linked below is just the latest among 4 studies I've reviewed from about 2000 to the present that appear to support the conclusion that the rate of weight loss does _not_ have an intrinsic effect on long term maintenance success.  That is important to know especially because a number of sources, some of them authoritative, promote that heuristic, such as claiming that people should lose weight at a particular gradual rate in order to maintain loss.  Fitness programs sometimes promote the reverse idea, that people can only succeed if they see dramatic results to encourage them. 

However the research seems so far to be telling us that rate has no intrinsic relationship to maintenance success in either direction. 

Collectively to me these studies don't seem to say that fast is better, and they don't seem to say that slow is better. 

I think it means that your choice of strategy if you are deliberately trying to lose and maintain weight for some reason should not be based upon rate by itself.   The heuristics of "gradual is better" or "fast is better" are very weak and should be rejected and replaced with more specific strategies that apply either more generally to people, or which have been calibrated more specifically for your own situation.  Haphazard use of the rate heuristic in isolation is implied by these studies to be very likely unhelpful.

Instead we should think about whether we are able to sustain the changes needed to lose the weight long enough to achieve our objectives, and consider how we are going to make the transition to maintaining a different body composition. 

Are we relying entirely on our enthusiasm to lose weight to trade off effort for early success, for example.  That's where fast early success can fail us, as our enthusiasm wears off and we find the things we were doing initially are becoming more difficult.

Conversely are we relying entirely on the assumption that gradual change is easy and sustainable?  This is shown to not neccessarily be the case.  People often find gradual change increasingly difficult to sustain eventually just as they find rapid chagne increasingly difficult to sustain. 

It isn't the rate itself that makes a difference, that impression seems to be partly a matter of us spreading weakly investigated but intuitively appealing information, and perhaps the compelling nature of the metaphor of rate and effort over time, where we tend to imagine something like trying to run up a hill and then falling back down vs. travelling over a gentle slope.  That metaphor breaks down apparently when it comes to weight maintenance over time.

(Vink et al., 2016)

Previous work with similar results:

(Nackers, Ross, and Perri , 2010)

(Das, Saltzman, Gilhooly, et. Al, 2009)

(Astrup and Rossner, 2000)