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Weight Maintenance Definitions, Revisited

Tuesday, June 12, 2012

While Russ gets the wekeepitoff.com site back up and running, I'm going to repost my columns from there on my blog here so I can refer to them when I need to.

Last year I wrote a column about the varying definitions of maintenance used in scientific studies. www.sparkpeople.com/mypa
ge_public_journal_individu
al.asp?blog_id=4323116


I followed this up with an illustration using data from contestants on the TV show, "The Biggest Loser."
www.sparkpeople.com/mypa
ge_public_journal_individu
al.asp?blog_id=4326080
In this second column I arrived at a definition of maintenance as "staying under a BMI of 30, assuming normal body composition."

I recently discovered a research article published in 2006 that reviews definitions used in the scientific literature and recommends using +/- 3% of body weight. (free to download, here: www.nature.com/ijo/journ
al/v30/n3/full/0803175a.html
)

If you're concerned with maintenance, this paper is well worth reading. The most interesting parts are Tables 1 and 2 which summarize the definitions of maintenance in scientific studies and the "Discussion and recommendations" section near the end.

The authors end up defining a working maintenance range as +/- 3% of a designated body weight.

Here is how they arrived at that number:
1) It needs to be expressed in % of weight because taller / heavier people experience greater weight fluctuations than shorter / smaller people and it has to work no matter how tall you are.
2) It needs to be smaller than clinically-relevant weight changes (generally accepted to be 5% or more of body weight). This is because if your weight changes enough to have an effect on your health, then you're not maintaining; you're either losing or gaining.
3) It needs to be bigger than usual weight measurement error due to hydration levels, etc. (generally 1-2% of body weight). We want the number to reflect actual weight changes, not random measurement error.

How you define the "designated body weight" is important, of course. As the authors point out in the "Biologic relevance" section, if you maintain an obese weight you might still have negative health consequences.

Let's use the same dataset of Biggest Loser contestants to see how this definition looks. We will arbitrarily define the "designated body weight" as the weight at finale, just to see how people might compare:
docs.google.com/spreadsh
eet/pub?hl=en_US&hl=en_US&
key=0Ah4KrA4GkhKgdC1JLXNFM
jBhZEtOOGNrRi1RZUh3b0E&output=html


I've added a column "% Change from Finale Weight" and sorted from smallest to largest. People who reported a "Current Weight" (on 12/1/2009) within +/- 3% of their finale weight are highlighted in blue in this column.

The four that had remained within the 3% margin were Estella Hayes, Jerry Skeabeck, Nichole Machalik, and Ali Vincent. They also happen to be four of the six folks who stayed within 5 lbs of their finale weight.

Here is where it gets interesting, though. Would you consider Jerry Skeabeck a successful maintainer? He lost 119 lbs and got to a BMI of 38 (severely obese). By some definitions (mine included, BMI under 30) he isn't actually DONE losing the weight, and therefore can't be considered "in maintenance" in the first place.

On the other hand Mark Kruger kept his BMI under 30 but gained back 21.15% of his weight. Would he NOT be considered a successful maintainer? I would argue that he has been successful at keeping his weight in a relatively healthy range, even if he did regain 33 lbs.

Obviously finale weight is not a great definition of "designated body weight" if you want to include BMI or other weight-associated health scales. And it is probably a poor "designated body weight" anyway, as the contestants were competing in weight loss for money and can make a legitimate case for needing to lose as much as possible for the finale without expecting to actually live at that weight afterward.

In the end I think I still like my current definition the most (stay under a BMI of 30). But that is how it should be, I suppose, since it's my life I'm managing. Each of us has to come up with a definition we think is valid and that we can live with. And then stick with it.

The most important is -- what’s yours?
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  Member Comments About This Blog Post:

VHALKYRIE 6/15/2012 11:25AM

    I guess I think of it in terms of "not regaining what has been lost". Kinda vague, but I tend to set my goals in terms of "precision" rather than "accuracy". For example, I may set my weight goal at 115, but if I stay consistent at 125 +/-2 then I consider myself successfully maintaining, even if I haven't hit my target.

Comment edited on: 6/15/2012 11:28:29 AM

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KAYOTIC 6/15/2012 10:15AM

    I do appreciate all the information you put into these blogs! As for defining "designated body weight" it most likely will be a very individual thing, but personally, after a lot of 'try-outs' at different weight ranges, I'm settled into a range that just feels right personally. And it happens to be in a BMI under 24, so that is "normal" in the classification system. I think as flawed as BMI is, at least it give folks a starting point in picking a goal, and they can then tailor it to their own liking once they get closer to that goal.

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BREWMASTERBILL 6/13/2012 7:17AM

    I guess I haven't thought of it in absolutes. I keep setting small incremental goals. Sometimes it is to gain weight, sometimes to lose it. So long as I'm somewhere between 160 and 190, I think I'm OK. 190 puts me on the cusp of overweight if you use the notoriously flawed BMI. However, at 190, I'd better be very muscular.

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