Weight Maintenance Definitions, Revisited
By Angela Baldo– September 19, 2011
We're continuing to find new research on maintenance definitions, but as the search continues, we often find answers just lead to more questions.
A definition can impose order and structure on a vague concept. And yet the research continues to show that pinpointing maintenance is harder than it looks.
Last year I wrote a column about the varying definitions of maintenance used in scientific studies. I followed this up with an illustration using data from contestants on the TV show, “The Biggest Loser.” In the 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 by Stevens et. al., “The definition of weight maintenance,” published in The International Journal of Obesity in 2006. This paper reviews definitions used in the scientific literature and recommends using +/- 3% of body weight. You can download the article for free and read it yourself:
http://www.nature.com/ijo/journal/v3.../0803175a.html
If you’re concerned with maintenance, the 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.
“The Definitions of Maintenance”
International Journal of Obesity, 2006
J Stevens1, K P Truesdale, J E McClain1 and J Cai
http://www.nature.com/ijo/journal/v3.../0803175a.html
Abstract:
There is currently no consensus on the definition of weight maintenance in adults. Issues to consider in setting a standard definition include expert opinion, precedents set in previous studies, public health and clinical applications, comparability across body sizes, measurement error, normal weight fluctuations and biologic relevance. To be useful, this definition should indicate an amount of change less than is clinically relevant, but more than expected from measurement error or fluctuations in fluid balance under normal conditions. It is an advantage for the definition to be graded by body size and to be easily understood by the public as well as scientists. Taking all these factors into consideration, the authors recommend that long-term weight maintenance in adults be defined as a weight change of less than 3%.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 our dataset of Biggest Loser contestantsto 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.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.
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 < 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 consider 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 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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Written by: Angela Baldo on September 19, 2011..
About Angela Baldo
From fatass to badass! Angela is a computational biologist in Upstate NY, who discovered extreme kayaking after her 180-pound weight loss. Now she holds her own on the rivers with men 20 years her junior. .No Comments
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