So That’s Why the Weight Comes Back!

For anyone who's tried to lose weight and been successful, only to see the pounds creep back on, there finally appears to be a biological reason:  hormonal and energy expenditure changes seen while weight is actively being lost persist over time and predispose toward regaining the pounds.  That's in the New England Journal of Medicine, and as Rick and I agree in the podcast, we're surprised and a just a bit embarrassed, having always chalked up regain to a failure of will. 

Not so, this study of only 34 people illustrates.  Here's what they did:  men and women with a body mass index of between 27 and 40 were recruited via newspaper advertisements.  Those who had other medical conditions or who were taking medications known to affect body weight were excluded.  Subjects were put on a very low-calorie diet for eight weeks and gradually reintroduced to a regular diet.  When the formal dietary intervention period was finished study participants were counseled about food choices and exercise and turned loose.  Follow up continued for another 52 weeks.

A number of blood markers were measured during the study, including hormones related to appetite and feeding.  Energy expenditure following a standardized meal was also evaluated.  Turns out that a bunch of hormones responsible for regulation of appetite were changed during the period of dieting and remained in that altered state through the one year follow-up.  Additionally, baseline energy expenditure was reduced while dieting and remained reduced for the study period.  Well.  Sure looks like our bodies have a compensatory mechanism for avoiding starvation that includes both hormonal changes and energy expenditure alterations that persist for at least a year.  No wonder folks who've lost weight have so much trouble keeping it off!

The authors state and we agree that compensatory mechanisms for avoiding weight loss are great when you're a thin, physically active bushman foraging for food daily, but when you're an office drone with abundant food all around you 24/7 and so many remote controls you may never need to leave your chair, these physiologic systems aren't helping and are undoubtedly contributing to the obesity epidemic.  At least though the study lends credence to that opinion we've heard put forward by so many who are attempting to control their weight that hormones really are involved.

So now what?  As any good study does, this one suggests a number of other questions:  how long do hormonal and energy expenditure changes persist following weight loss?  Can we intervene in changing hormonal levels and does that help in maintaining weight loss?  Is there a lynchpin with regard to managing the whole weight maintenance apparatus?  And so on.  For now, at least, the study offers hope that with increased understanding of the mechanisms effective interventions can be found.

Other topics this week include sleuthing out the cause of hemolytic uremic syndrome in the recent bean sprouts-related E. coli outbreak in Germany, also in NEJM, a lack of benefit seen with screening chest x-rays for reducing lung cancer mortality in JAMA, and bisphenol A and it's impact on behavior in kids in Pediatrics.  Until next week, y'all live well.

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Why The Weight Comes Back? | 2020 WeightLoss.Com
November 28, 2011 at 10:01 am

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roney24 January 13, 2012 at 3:21 pm

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