Well, I've got to back up everything Aris says.
First, you cannot criticize me for telling someone that they are overweight when they are in fact overweight. IT'S MY JOB. I'm a doctor. I'm allowed to be "rude" about such things. If you are fat, I will tell you that you are fat. I am fat. I struggle with it. (My personal demon is portion sizes.) But, like anyone else without some sort of metabolic derangement, if I can muster enough willpower I can lose ALL of my excess weight. I've done it- I have restricted myself to very low caloric intake and lost ridiculous amounts of weight very quickly- probably too quickly. (Fifteen pounds in a month is too quickly.) That was hubris, I admit, and I was quite uncomfortable while doing it.
That said, while I do tell my patients that they are fat if they are fat, I do not walk up to random obese pedestrians within my field of view and accost them. As Aris says, you never know their situation. And, frankly, it is none of my business. If they ASK me about their weight then all bets are off, though, and I will not shirk from telling someone that they need to lose weight out of some sense of "politeness." I'm pretty tactful, though, and in general can critique without being offensive.
The MetLife height/weight tables are a useful approximation, but they have their limits. For example, if you are a body-builder who is very muscular and has a very low body fat you will almost certainly chart as "obese" on the MetLife tables. Lean body mass (or, secondarily, body fat percentage) is a better metric, but is difficult to measure accurately. So, Sarah, you might be doing very well, in truth, if you are conditioning the way that you say that you are.
I wholeheartedly support all opposition to the current "Oprah-fied" trend in society to consider obesity as normal. I've done >100 bariatric surgeries and let me assure you NONE of those people were physiologically incapable of losing weight. They were PSYCHOLOGICALLY incapable of losing weight. If they had a physiologic problem then I would not have done the surgery- I would instead have treated their hypothyroidism or whatever it was. Almost all of these poeple blamed their "glands", but had normal TSH on the labs.
It sucks, but the truth is that with enough willpower you can lose weight. (Sorry, Sarah. Love you.) Watch one episode of "The Biggest Loser" if you want proof. (I am not endorsing such extreme weight loss, but it does support my point.)
I will back Sarah up, though, when she says that it can be hard. But, well, sometimes you have to work for it if you really want something, y'know? And some people DO certainly have to work harder than others- people's metabolisms DO differ. The Vermont prison study proved that pretty conclusively.* It is especially hard, as she says, to both condition and lose weight at the same time. I generally focus on one at a time. (I'm currently in "lose weight" mode, counting calories, and I've lost five pounds in the past month. I know from experience that it will then be much easier for me to work out intensively, and re-condition.)
And western diets suck. That makes it all even more difficult, I know.
And, as far as how pack weight differs from excess body weight- my mind boggles trying to fugure out how pack weight is worse on the knees (or whatever) than excess body weight. Maybe there is some ergonomic reason, but it must be pretty small.
Still, I advocate expanding HYOH into the rest of you life on this one- if someone is a bit of a gourmand (like Sarah?) and decides that eating well keeps them happy, and they are willing to tote a few extra pounds, well, then they are happy, aren't they? Granted, it would be even better if they were a gourmand who was willing to work extra hard to keep the weight off (again, like Sarah?). And I will certainly advise them to lose the weight if they exceed "overweight" and nudge into "obesity." But I'm not one to deny another person happiness if I can help it. A few extra pounds is -realtively- harmless, as long as they don't keep accumulating, or cause secondary problems like hypertension, diabetes, or whatever.
But some people are simply screwed by their basal metabolism, and will have to work much harder to keep from becoming obese. It isn't fair, but then life isn't fair, is it?
By the way, how much fat or carbs (or whatever) that you eat has very little effect. All you have to do is worry about calories in versus calories out. (And, of course, be sure you're getting enough vitamins and protein and whatnot.) The exception is the Adkins diet which I think actually does work due to the ketogenic effect, but it isn't very healthy, and is actually harder than just counting calories.
Caories-in/Calories-out. Say it with me…
P.S. I'm just mentioning you specifically because of things you have posted in this thread, Sarah. Obviously, I have never met you, and I'm not trying to present my little comments as facts or criticisms. I'm just trying to better explain what I'm saying.
Love your book, by the way. It certainly changed the way I pack food for the trail.
* The Vermont prison study worked thusly: The investigators offered prisoners better food than normal prison fare in exchange for participating in the study. The deal was, they had to eat exactly the amount of calories the investigators assigned to them. They found that some individuals could maintain their body weight even if they took in huge amounts of calories a day, whereas others would put on weight at 2000 calories a day. (Caveat- I think these were all males, though they were all screened for metabolic derangements first.)
So, there is quite a bit of variance even among normal individuals.