Steve Pope wrote:
>
> In rough terms the fraction of people who are succeeding is going to
> be greater than 5% by a factor that's on the order of the typical
> number of attempts in a five-year interval.
>
> What I frequently see is commentators sliding between "95% of
> weight-loss attempts fail" and "95% of persons attempting weight-loss
> fail" but obviously these are two very different statistics.
> If the first number is correct, the second number is very incorrect.

Right. Either 5% of dieters eventually succeed or 5% of diets
eventually succeed. I think it's dieters but I do not have the data to
know that for sure. Lacking the data my guess in one direction is no
better than your guess in the other direction.

> Another thing I see from commentators is discounting successful
> weight loss attempts unless the magnitude of weight lost
> exceeds some value (which is often not stated).
> So a statement such as "95% of persons who attempt sustained weight
> loss of at least 40 pounds fail" could be true, while at the same
> time the statement "95% of persons who attempt sustained weight loss
> of at least 10 pounds fail" could be false.

The case of 10 pounds does matter. Loss is some combination of water
(icludes glycogen carbs stored by dissolving it in water), fat, lean,
bone and so on. Of course the loss that nearly everyone wants is fat.
The problem is water loss is easy to acheive, nearly impossible to
retain and is as much as 10 pounds in some people. When I managed to
estimate my water retention swing during maintenance it appeared to be 6
pounds that randomly comes and goes without any sign of fat lost or
gained. The chosen threshold for sustained loss must be large enough
that it can not be water.

> That is my perspective. I haven't seen anything that contradicts
> the 20% to 30% numbers, but I'm open to seeing such data if
> it exists.

I would love to see data that tells which of our guesses is closer.
Until then we're stuck with our guesses and our guesses disagree.