Continuing in my discussion of obesity myths, presumptions and facts published recently in the New England Journal of Medicine, we turn our attention to obesity presumption #4:
“Weight cycling (i.e., yo-yo dieting) is associated with increased mortality.”
This presumption is based on the observation that,
“In observational studies, mortality rates have been lower among persons with stable weight than among those with unstable weight.”
Again, we are reminded that correlations do not prove causality and it is easy to imagine all kinds of confounders and other factors that could lead to finding such a correlation.
But, not only, is this a finding that has has not been confirmed in several more recent large epidemiological studies, as the authors point out, there is also little support for this idea from experimental animal studies – intentional weight cycling has simply not been shown to shorten life spans.
Indeed, regular readers may recall my more recent post showing that that short-term weight cycling does not appear to have consistent adverse metabolic effects.
However, as I have pointed out, irrespective of whether or not yo-yo dieting shortens your life span or increases your risk for cardiovascular risk factors, the emotional impact of repeatedly losing weight only to put it on again may not exactly be conducive to good mental health and quality of life.
It is certainly easy enough to see why people who manage to maintain their weight constant, rather than losing weight just to regain it, may well end up being healthier (and happier?) in the long run.