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.
Wondering how to define “weight maintenance?” Researchers do too
BY ANGELA BALDO – MARCH 16, 2010
POSTED IN: ANGELA BALDO, AUTHORS, LIFE POST FAT PANTS, UNDERSTANDING MAINTENANCE RESEARCH, WHAT IS MAINTENANCE?
Maintenance isn’t always what you think it is, scientifically. What you see in all the success stories is skinny people, folks that lost weight and presumably stayed there. But the research doesn’t necessarily define maintenance that way, or even stick to one prevailing idea.
So if you’re confused about what’s actually “maintaining,” don’t worry. What we’re trying to say is, “Look, not only do you not have a universal definition of maintenance, nobody does.”
One of the problems with interpreting the scientific literature in weight management is that the working definitions of “successful maintenance” may not match our own notions. And even worse, the definitions are not consistent from one study to the next, even sometimes in papers from the same research group!
No matter the differences, every definition contains two basic parameters:
- The amount of weight lost
- The amount of time the weight was kept off
From a range of scientific studies, here are a few different interpretations:
Keeping at least 5% of their body weight off for 15 years
Keeping 30 lbs. off for a minimum of one year
Staying within 5 lbs of goal weight for one year
Keeping off at least 10% of the starting body weight for one year
Maintenance can be measured in terms of the original maximum weight or the lowest weight ever achieved, or both. I selected a few studies from my collection to provide some examples. The 2000 paper I mentioned in my previous column defined successful maintenance as keeping at least 5 percent of weight off for 15 years. As I mentioned earlier, roughly 6 percent of the subjects accomplished that. The data from this study span 1975 – 1990.
In 1993, the National Weight Control Registry (NWCR) began with a different definition. To participate in the program, you must keep 30 lbs. off for a minimum of a year. To participate in the Registry at all, that’s still true today.
But even then, individual studies from the NWCR use different definitions of “success.” A 1999 NWCR paper defined “successful maintenance” as staying within 5 lbs of goal weight for one year. This is what I think of when I say “maintenance,” and I’m fairly certain it’s a common idea.
This changed in 2001. Since then, NWCR publications frequently define successful weight loss maintenance as keeping off at least 10% of the starting body weight. This amount of weight lost will not usually take someone from obese to non-obese status.
They use this definition because it’s rare for many obese people to achieve a healthy BMI, what they called “weight normalization” in this paper.
So the NWCR scaled back the definition to mean a loss that is more modest in terms of actual pounds (10%) but still significant in terms of health benefits.
With the definition also comes the caveat that research draws a distinction between whether the maintenance was intentional or the result of illness.
Without a consistent definition of maintenance in the scientific literature, it makes determining your own idea of maintenance that much more confusing. Some studies consider the lowest weight within any time point between the lowest weight and now, even if it has been regained. Others consider regain between the lowest weight and now as unsuccessful maintenance, even if the subject lost the weight again later. When you actually take the second data point is significant with a process like weight management, where fluctuations are common.
Even with all of the differences between our personal definitions of “successful” maintenance and between those in various scientific studies, these are the best data we have, so we will use them. When I summarize papers in this column I will attempt to clarify the specific working definition of maintenance for each study.
But the bottom line is you’re weight’s always going to creep up. You just have to keep pushing it down. We have to do the best we can with whatever information is available. Strategies that help people keep 10 percent of their weight off presumably will help me keep 54 percent of my weight off. At least that’s my hope.
More blog posts about maintenance definitions:
Familiar faces from Biggest Loser illustrate how wildly maintenance definitions vary
Weight Maintenance Definitions, Revisited