Hi, welcome
Being overweight myself I've got what I think is a measured view on this topic.
Obesity means a combination of lack of will power, hereditary factors, temptation and a cyclic rotation of all factors. It's not complicated, it just near impossible to overcome without medical and/or surgical intervention.
Most certainly a GP visit can be more than beneficial. I would also suggest that talking won't help in fact such is this impossible fight within him, he could easily begin resenting you.
There has been many breakthroughs recently in the medical world you could investigate. In the meantime "let's go for a walk" would be much more preferable than "that's junk food".
Finally, like giving up an addiction, you'll have to wait for it to arrive, you can't rush it. Hence the medical options are more realistic.
Good luck.
TonyWK
