Boats Fast and Slow

The Fast Can’t Last Weight Loss Myth

One deeply entrenched weight loss myth is that if it’s fast, it won’t last. In the words of CDC, “people who lose weight gradually and steadily (about 1 to 2 pounds per week) are more successful at keeping weight off.” It turns out that this advice is an article of faith that doesn’t hold up to scientific scrutiny. A new randomized, controlled study published in Obesity finds that with comparable amounts of weight loss, the rate of weight loss, fast or slow, has no effect on the risk of weight regain.

This finding should be no surprise. Three years ago the “fast can’t last” myth was one of seven myths identified by Casazza et al in a review of myths, presumptions, and facts about obesity published by the New England Journal of Medicine.

For the present study, people with BMI between 28 and 35 were randomized to treatment with either a low calorie diet for twelve weeks or a very low calorie diet for five weeks. After four weeks of subsequent dietary support aimed at helping the subjects stabilize their weight, they were followed for another nine months with no dietary intervention. The two groups initially lost similar amounts of weight. And nine months later, weight regain was indistinguishable between the two groups. The authors note that their finding “directly contradicts the current dietary guidelines of several countries, which recommend a more gradual weight loss approach for prevention of weight regain.”

Tortoise and the Hare, Illustration by Jean GrandvilleThree years ago, Casazza et al got right to the point:

Although it is not clear why some obese persons have a greater initial weight loss than others do, a recommendation to lose weight more slowly might interfere with the ultimate success of weight-loss efforts.

The myth of superiority for slow but steady weight loss is no more scientific than Aesop’s fable of the tortoise and the hare. Let’s keep the fable for bedtime stories and drop the myth from guidance about health and wellness.

Click here for the study in Obesity and here for the analysis of obesity myths, presumptions, and facts in NEJM.

Boats Fast and Slow, photograph © Jan Christopher Chua / flickr

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January 29, 2016

6 Responses to “The Fast Can’t Last Weight Loss Myth”

  1. January 29, 2016 at 10:22 am, Todd I. Stark said:

    I suspect that there are a few sources for this idea, some more reasonable or reliable than others. Perhaps the most reasonable in my mind is compensation for short term efforts that people cannot sustain. The idea is that if someone is doing something that brings their weight down very rapidly, there is: (1) a very good chance that they are doing something they cannot do for very long, and (2) it is also independently likely that they will not be prepared to maintain their weight loss by switching to some different strategy at some point.

    So regardless of whether there is a necessary direct relation between weight loss rate and long term success, the guideline reflects in part the need to consider what you will need to do in the long term rather than just the short term.

    If it turns out, as it seems to according to this editorial, that rate does not have a necessary relation to success, then we still need to be careful about the time frame consideration.

    Things that help us trade off enthusiasm for early gains are not always transferrable to long term success, and it probably will help to make people more aware of that regardless of the strategies they chose to improve their health or appearance.

    • January 29, 2016 at 12:54 pm, Ted said:

      Good analysis, Todd. The short term rate of loss does not matter in either direction. So the energy should not go into persuading someone that either fast or slow weight loss is better. The energy should go into the long term outcome of maintaining a healthy weight, which is, all too often, ignored.

  2. January 30, 2016 at 4:26 pm, Allen Browne said:

    Obesity is a chronic, incurable disease.

    • January 30, 2016 at 5:13 pm, Ted said:

      That’s largely true today, Allen. I would only add that with good evidence-based care, it is manageable. Since you are a provider of such care, you know this better than I do. Thanks for the work you do.

  3. February 01, 2016 at 7:55 am, Allen Browne said:

    The tools are certainly on the horizon – if not staring us in the face. The problem is how to get them to the providers and the patients, Thanks for the work you do.

    • February 01, 2016 at 11:01 am, Ted said:

      Thank you, Allen.