Anyone telling you how to lose weight should have at least tried their methods on themselves.
If they don't have good before and after pictures, they're full of shit.
On the other hand, don't take advice from someone who's obviously in good shape and always has been. They have no idea what the problem even is.
It's a bit like sports coaching. If I want to learn how to play tennis, I'd be an idiot to take advice from someone who's not very good at tennis.
But it would also likely be a bad idea for me to take advice from someone who's really good! (as in top five thousand good). Those people were naturally talented youngsters, and were shown what to do so early they have no idea how they do it.
The best coaches are almost always clever people who aren't particularly naturally talented, learned as adults, and became as good as their physical abilities would allow by thinking about what to do and how to do it.
And even those people have an awful lot of work to do before they can coach people who have problems they themselves never had, or who've learned things in a different order to them.
It'll be the same for weight loss, you mark my words.
Don't take advice from the thin, don't take advice from the fat. Take advice from people who were fat and are now thin. What they did has worked in at least one case.
And just like with sports, when people who you have reason to believe know what they're talking about give you advice, you owe them and yourself to try it once. Once.
If it doesn't obviously work and obviously instantly improve things, then it's either bollocks, or you've misunderstood, or it's good advice for someone else.
A great teacher will not give such advice, because he will be able to see what you personally need to do just by looking and thinking, and he will make sure you understand what he's asking you to do and why.
A good teacher will react to the failure of their advice by trying something else, or saying the same thing in different ways until it does work.
A rubbish teacher who is wasting your time and should not be teaching will react to the failure of their advice by doubling down and telling you to try harder.
Trying harder never works
The first commandment is 'build form'. Until you're doing it right, trying harder is futile, and it often makes things worse.
lol, pic related?
I agree with the sports analogy, because it allows for enough nuance.
I think it's possible to be a great coach without being a great player, but you better be able to show results in players then. Many great coaches used to be great players. Some weren't. But it seems to help.
It seems clear that taking dribbling or dunking advice from Michael Jordan is not going to be helpful to most people. "Just go around the other players and put it in!"
I'm still 238.5lbs (as of this morning) and I'm doling out dieting advice. What you could say is: I've made great progress (54lbs or 10 jeans sizes down) but I'm not fully there yet. It's definitely worked, and maybe it stopped working for a bit, and hopefully now it's working again. It also seems to work, at least initially, in pretty much everybody who tries it, though some have trouble pulling it off.
But if I'm still obese in 5 years, or 3, you better ask what's going on.