It's important to distinguish weight loss from fat loss. We want the latter - the former in itself is not particularly desirable (except perhaps for ice fishing).
- When I exercise, I tend to build muscle (and sore legs).
- When I eat less, I tend to lose some weight.
- When I exercise but eat more, weight goes up - because I'm gaining muscle.
So far, so good. But the above is completely meaningless. What really matters is:
- If I'm exercising a lot and eating reasonably, my weight goes up, BUT my %BF (percent body fat) goes down, because I'm gaining more muscle than fat.
- If I'm doing low-intensity exercise and eating sparingly, my weight goes down, but my %BF remains stable.
- If I exercise like crazy and eat very little, my weight goes down and my % BF goes down. This happens rarely because it requires inhuman willpower.
The point of this (admittedly anecdotal) chart is that weight change and %BF change are NOT correlated. In particular, the way one achieves a low body fat is:
1. Increase muscle, lowering %BF.
2. Lower overall weight, causing net fat loss AND muscle loss, probably increasing %BF slightly.
3. GOTO 1.
If you lose more %BF on step 1 than you gained on step 2, you win. This zig-zag is what body builders do, because it's nearly the only method that works. And step 2 is very diet-sensitive, and rather finicky.
And that is why the article sounded stupid to me. The study, in particular, of women who exercised intensively compared to those who didn't. I hope they measured % body fat in that study, because it's the only thing that matters when talking about obesity.
When the article says something like "Everybody lost a bit of weight, but some of the exercisers gained weight! So exercise doesn't make you thin." That's crap. "Lean" is a measure of % body fat, not total body mass. The exercisers probably decreased %BF if their weight remained stable. In other words, they probably look better now than they did.