"The lack of the specific pronoun "ele" makes "it" a better choice than "he"."
Is this something specific of Portuguese? I haven't noticed any differences in the omission of the subject between Italian and Spanish (my native language), but maybe it is different for Portuguese?
On the subject of "é" vs "está": pesado may be a transient state. In Spanish "está pesado" is not incorrect at all (refering to a person) - it's just a polite way of saying someone is fat. It would be useful if someone could confirm if this is a correct use in Portuguese or could be a "false friend".
You need the personal pronoun to tell you it's a person. Without it you assume someone's talking about an "it".
"Estar pesado" is indeed a euphemistic way of phrasing "estar gordo" (fat). Again, because you're using "estar", a transient state is implied, just like in Spanish.
- "Eu estou mais pesado depois desse ótimo jantar". ("I'm heavier/fatter after this/that great dinner", implies a simple change of weight).
- "Eu sempre fui um homem pesado" ("I've always been a heavy/fat man", implies a state of being, something that has become a part of you and how you define yourself).
I don't wanna overconfuse you, but at least over here someone would be able to use "estar" with height, a height long as they're undergoing that change (and highlighting it):
- Estou mais alto do que quando era criança (I'm taller than when I was a child).
Because height becomes relatively more fixed than weight as you enter adulthood, it easily becomes a part of you, a state of being [tall, short, or something in between].
P.S.: It's important to stress that children and old people are also "tall/short" (in comparison with other members of the same group), and this state of being is always marked with "ser".