Spider-Man has gone in the opposite direction with some artists. If you look at how Ultimate Peter Parker is drawn for example, he looks much scrawnier than the teenaged Peter of the 616. Even the adult 616 Peter is sometimes drawn skinnier in modern comics than he was as a teenager in the '60s.
Yeah, they've been emphasizing his youth lately. As a result, he's gone from looking 170 or so, to looking maybe 135.
I wouldn't say that applies currently. Mile Morales has filled the niche of young Spider-Man, while Peter is being allowed to mature as a veteran superhero (he's officially been Spider-Man for 13 years now), who teaches rookie mutants at Xavier Academy while heading a billion dollar, global tech firm. Also, Peter isn't being drawn that skinny in AMAZING at the moment.
I've seen some very scrawny depictions of him during the last 20 years though. In particular, I was struck by the way John Romita Jr. went from drawing Peter like this...
... to this. Not sure why he made that change, as Spidey looks abnormally thin in the latter image, like someone with an illness or eating disorder.
I prefer a more classic depiction. Here's how John Romita Sr. drew Spidey next to the Avengers. Smaller than the male Avengers, but still strong and athletic-looking in his own right.