And you’ve probably just identified some examples of where the correlation is not 100%!
You mention you don’t eat particularly healthy food, yet you are not overweight … strong correlation between eating unhealthy food and being overweight!!!
I always think it is amusing with people talking about fitness and weight, and how a person who is overweight puffs whilst going upstairs - you would too if you were carrying a backpack of that weight. That person might not be less fit than you but we see the external signs we believe shows unfitness and make a judgement.
Humans are also very good at being “fit” for certain tasks … carrying a baby is one which is really interesting … parents develop and then lose this capacity … your housecleaner is very fit and very much “in shape” for housecleaning … maybe not for going to the gym though!!
Though this question really was answered in the first reply - more calories in than out.
No offense, but I don’t think that’s a very good example. If somebody is huffing and puffing BECAUSE they’re carrying around a lot of extra body weight, then I think that’s a situation wherein the external signs do indeed show a lack of fitness.
Mind you, I understand that someone can be fit despite some extra body fat. One of my favorite fitness instructors is by no means skinny, but she has plenty of strength and stamina. She herself will gladly admit that she has some excess pounds, but she’s in really good shape.
If someone has trouble climbing stairs, though? I think it’d be kinda foolish to say, “Oh, she’s only huffing and puffing because of all that extra fat. She’s actually quite fit.”
I recently helped my mother move. It was a very large and difficult move, with lots of heavy pieces of furniture and at least 9 tall, fully stocked bookcases (plus several unsorted piles of books for which there was no room), and the destination apartment was a third floor walkup.
We were all mightily impressed with the strength, skill, and endurance of the movers. They spent a good five hours simply on the back end of the move, lugging very heavy things up stairs with, as far as I could tell, no meaningful breaks. By most objective measures, they were in fantastic shape. And no doubt they do this sort of thing several times a week. And yet, they looked like a normal cross-section of Americans: a couple were slender and buff, most had a good-sized paunch, and a couple of them were simply overweight. One guy in particular had to be at least 320 pounds, quite fat, and yet he worked just as hard and as long as anyone.
So yeah, clearly strength/stamina and being slender are only indirectly correlated, and even someone who’s extremely capable physically will be fat if they eat enough.
A friend of mine is a big gal and has been for as long as I’ve known her. She’s 5’10" and I’ve seen her range anywhere from 225 - 350ish pounds. No matter her weight she is fit for her size. Her stamina is incredible and I’ve seen her carry stuff that has impressed me quite a bit.
You can’t always tell by looking at someone what they are capable of.
This is true. Fat or not, if someone is ‘in shape’ they are able to perform physically at their current weight. Underweight people like me can be quite fit and strong, and overweight, fat, even extremely obese people can be as well. I work in a blue-collar industry and men with challenging and physical jobs (carpentry, plumbing, masonry) are very often extremely overweight, but still have impressive strength and endurance for the what they to do - plenty of lean guys with impressive gym muscles would be exhausted by what they do each day. If you train, your strength and stamina will improve, weight is inconsequential to this (although often people will see some weight changes when they take up a new training regimen, even if they aren’t focusing on diet).
Even without exercising fat people develop heavier bone, and muscles, that enable them to perform physical tasks - a very fat person, although they usually have very high body fat compared to thinner people, has developed enough lean mass to be capable of supporting the extra fat. A person of 350 lbs climbing stairs just can’t be compared to a person of 200 lbs carrying a 150 lb load up the stairs.