[gaius]

1,000 calories, considering the modern possibilities, isn't that much. I mean, that's a bit less than two slices of toast with Nutella.

Yes, it is VERY difficult to out-train a bad diet. There is an example I use with friends, which is if you drink 5 pints of beer, you'll need to run 10 miles to burn that off (really). Have a pizza or a kebab on the way home, another 10 miles. Have a fry-up for breakfast, another 10 miles. So even if you ran a Marathon tomorrow, with your hangover, you've still gained fat from one Friday night. And you're doing again on Saturday night too.

On the subject, of athletes, everyone at the top of any sport is a genetic freak. That's not to disparage the effort they put in. But hey, Michael Phelps didn't get his extraordinarily long armspan from training. He didn't get his flipper-shaped feet from training. He was born with them. And he was born with an extraordinary metabolism too.

[mr_luc]

I agree that it's difficult to out-train a bad diet. But

1) Remember, we're counting the difference between what you need to eat and what you do eat. So although crazily irresponsible people doubtless are regularly eating 5000+ calorie diets, day in and day out, the amount they need to burn off to zero out would then be around 2000+ calories.

2) Impractical is not impossible. Even if you OVEREAT by 3000 calories per day, if you spent all day running and resting/drinking water from running, you could do it.

Exercise CAN make people thin. ;) I'm not saying that for a given someone, you couldn't eat enough to take yourself out of contention, but the answer to "Can exercise make you thin?" is "yes."

What I object to most in the article title is the implication that people are working hard, but somehow wasting their effort.

"Oh, the problem is that you've been getting up an hour early every morning to run and run and run, and have been undoing all of your hard work by eating Hardees Thickburgers 3 times a day!"

If you have the self-discipline to run regularly, you have the self-discipline necessary to complement it with the MINIMUM of dietary caution necessary to let it work for you.

[caffeine]

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.

[gaius]

if you spent all day running and resting/drinking water from running, you could do it.

Well, I am a Marathon runner. I know what burning 3000 extra calories in a day feels like. There is no way I could do that every day, and the average person is a LOT less fit than me.

Exercise is important for many reasons, but fat loss is mostly about the diet.