Should I tackle my son over drinking so much diet soda?

My first thought is that you won't help your son by trying to stop him doing something that he seems to be doing for his own reasons. If he's depressed, maybe this helps him cope with his feelings, so telling him you think he's drinking too much soda isn't very helpful from his perspective. It sounds like you realise you are expecting too much from him.

As a son, he wants so much to make you proud and feel your love, so if he can't live up to what you want of him, that will be very painful for him.

So take a look at your expectations, and try to separate out what are your needs--such as for him to be healthy and happy--and what might be his need for you to love him and express that love when he is unhealthy and unhappy. This might help you decide what is "appropriate" (or helpful), and what is not.

You don't say how old your son is, so it is hard for me to advise other than to caution about your current line of thought, but in general I'd look for a way to support him and co-operate to help him get *his* needs met. As a parent this is difficult, especially when you feel responsible and often powerless when a son is in adolescence. You need to find what is an appropriate balance between setting boundaries (which varies according to his age) and allowing him to make decisions for himself, and to make and deal with the consequences of his actions.

I suggest this is very difficult, and that there is no correct answer, just the best you can do as his father at the time. What matters most is that you care and that he experiences that you care, even though he may not thank you for it.

It is also ok to ignore my cautioning and suggestions, and to trust your own judgement, so long as you take responsibility for those choices and the consequences (e.g. rather than blaming him should you or he fail in your own eyes). He'll learn a lot from a father who can do that, or can at least try!

There's something very special about the love between a father and son so its great to receive a question from a father who is so caring and wants to help his son. I wish you and your son the very best.