To tell son it’s too much and affecting his dad’s self esteem.

Double bolt the front and back door so he can't walk in until your up. Also my parents like a lay in, my dad has bilateral lymphoedema, eats a good diet and is v active. But his legs are what they are now and won't change. As your son doesn't appear to want to listen or respect your boundaries then you shall have to enforce them physically, in this case access to the property.

The thing is all the posters on here saying your son just wants his father to look after himself better @myfairladies might be right. Or your son is just very rude and insensitive. Has he got a girlfriend/boyfriend to spend time with instead of you and DH?
I do get a bit a bit fed up with younger people thinking they know what is best for older people. If only you ‘do everything right’ it means an old age free of ill health. Of course we can do things to help ourselves as we age. However all the dieting and exercise in the world doesn’t magically guarantee a healthy old age.

Ha. I've one a bit like this. Very big on diet, health, the environment, and can be quite evangelical if not reined in. My response was to acknowledge I was pleased he had found a lifestyle that worked for him, and that I'm sure there was evidence it was great way to live, but that it was anti social and rude to criticise and shame people who lived differently, and that its known not to be effective in changing people.
Any straying into that territory now is met with "its rude to be critical of us" or similar.
The important thing is not to engage, defend or justify. It just gives them grist for their mill and prolongs the thing. Because unfortunately you'll not 'win' because they're objectively 'right'.

I think you need to role play this with DH to support him to toughen up eg

DH - I need you to drop this, I don't want to change and would prefer a chat without you criticising me.

DS - carries on

DH - I've asked you to stop, if you don't I need you to leave

DS - carries on

DH - I need you to leave, now

DS - looks to you

You - DS, you've been told by me and your dad repeatedly to stop. You need to leave until you can come into our home without constantly criticising us. Walks him to the door.

And yes, lock the door, put the chain on. Pre-warn DS that you will be having a lie in and not available until X time.

Your son’s an arsehole. Get your key back and tell him to knock it off

Why doesn’t your DH just tell him to piss off? Why are you getting involved? I can see why it’s annoying but I think it’s not your battle to fight

I'm not so sure he's a lovely lad.

That you can and should do something about.

When he asks why, you can tell him you’re fed up with him letting himself in too early and banging on about food and driving. You’d rather he texted first.

I think adult children need to understand that their parents have capacity in situations like this and you don't have to agree with all their life choices. You also have agency. I know what it's like to watch a parent on a one way road to ill health but it was never on me to batter them over the head. All I can do is make the best choices I can now in relation to the consequences. It's hard, but that's life. They still have capacity and still make choices I think are detrimental, but it's their life. I can choose the level of my involvement and what would be the point in my involvement being absolutely nothing but constant criticism?

Your DS needs to lay off his Dad but at 55 it's not too late to change his lifestyle and do better, for himself, you and your kids. Reading between the lines it does sound as though your husband needs to make some changes otherwise he will send himself into an early grave.

Children find it exceptionally difficult seeing their parents decline and age, especially prematurely. It sounds like your son is seeing the start of your DH not looking after himself and is worried for the future. Although, he should treat his dad with kindness rather than contempt.

What bits about him are lovely? Because from what you’ve described he seems like a bit of a knob.

Can you leave keys in the door on the inside so he can't get in?

When he complains, you might suggest that if he continues to come round at early o'clock that you'll change the locks and he won't be getting a key.

With respect to your husband's health, if he is willing to improve his health it can be done at his age. My husband has dieted himself out of diabetes and had a blood pressure of 100/80 yesterday at his health check. He was previously morbidly obese and at serious risk of a heart attack or stroke. He's 62. We eat well, just no white carbohydrates, eating between 11 and 7 and he has a 15 minute walk every morning.

Obviously it's up to your husband and he shouldn't feel obliged to do anything he doesn't want to.

It might be misguided concern, but still incredibly rude.

I would consider taking his key back. He does not live there. Tell him he is welcome to come over and you love him, but since he doesn’t respect your boundaries, you want him to call ahead.

I thought you were going to say he's 75, not going to get on a bike now.

But he's 55! That's young. And as others above have said, this sedentary lifestyle will come back to bite him on the bum if he doesn't make some changes.

A middle ground can be reached I am sure. And get that key back!

Agreed.
He isn't trying to help his dad by nagging.

Ask for his key back. He can't just walk in now he no longer lives there, that's just disrespectful. Do you have a key to his place? Do you just walk in his place whenever you want? Your son probably wouldn't like that. Time to have a conversation about boundaries. New rules now he doesn't live with you. No early morning visits before 10/11am, you decide the time. Text to arrange visits both ways. Stop the negativity. Full stop.

Yep I get frustrated when I think my parents aren’t looking after themselves properly. I am kinder now than I was in my 20s but they are now in their 70s - I will still tell my dad he needs to get out for a walk though.

your DH is only 55! If he is already overweight and sedentary, he is going to be really unhealthy in 10 years, and is unlikely to reach old age without serious illness. Your son might actually have a point.

id be encouraging DH to eat better and exercise, at the same time as saying to DS to be a bit kinder with him.

Well that's quite the leap are you ok you seem angry.

You’ve nailed it.

Your son sounds insufferable and as someone else has already mentioned, mid-twenty year olds often are. I must have been very irritating, I knew all sorts apparently. Ahh, youth.

I find the relationship dynamic really interesting here. There's no way I could have mocked my parents for not being out of bed by 9, they'd have sent me away in a box. So, well done for encouraging a relationship that goes in the other direction. But perhaps it's time to be firm. This could be really corrosive and while your son may emerge, blinking and humble, in his thirties and think christ, what a wanker I was, the damage may be done. You and your DH don't need to let this happen to you.

You need to set some boundaries with your son. Tell him what time he can visit from. He shouldn't just drop around and expect you to jump to it. You spend your mornings how you like.

Nip the criticisms in the bud. When he spouts them, call him out however is appropriate. Or just tell him outright that you are not interested in his judgement of you and how you choose to live, so knock it off.

It’s because he knows he’ll have to care for you both when the shit hits the fan due to long term unhealthy habits. He’s in a panic and now he’s independent he knows it will fall to him being local. Which it will.

That's easily solved then! New lock should do it.
Download one song that is perfect for him and others of the same ilk, 'Oh Lord it's hard to be humble when you're perfect in every way'.
Why do adult children think they can behave in a way that were their parents to behave the same way towards them they would be up on their hind legs complaining?

Your son has some big character flaws.
It may be a bit late for you to do anything about it, but as his parent you need to try and correct him.
Sit him down and tell him loud and clear:

. Trying to always 'win' an argument is obnoxious. People don't like it and he needs to learn when to back down and shut up, agree to disagree.

. Checking out the contents of someone else's fridge is unspeakably rude. He does not live in your house any more, he is a guest, so he is not to open your fridge, much less comment on the contents.

. It is rude to turn up at someone's house unannounced early in the morning. All visits must be pre-arranged. Again, it is not his house, he is a guest.

. The key he has is for emergencies only, he should knock on the door and wait for you to answer.

. No-one is more boring than a person banging on about their new diet or new health or exercise regime. Other people are not interested. Tell him to find other topics of conversation.

. It is very rude to comment on other people's weight or health. Even if it is a close family member. Even if it is his dad and he is worried. It is just not his business, he needs to learn manners.

Don't mince your words or pull your punches here. He is bang out of order, and if you don't tell him who will?
If he goes through life like this he will soon have no friends.

This was me and my stepmum. At 55, her lifestyle was that of a 80 years old already. Overweight, smoking, drinking, and no physical or even mental activities at all. My dad was the opposite. The frustration was that I could see the future whilst she refuses to acknowledge it.

We have now reached that future. At 75, she can hardly walk 100 metres. She does nothing all day. She is depressed and frustrated. She is jealous of my dad who can still do everything. She resents it and it sometimes shows in her behaviour towards him.

The worse though is her constant expectation of empathy. Frankly, I find it hard to give it to her. She had everything, and I mean everything given to her to avoid being in the situation she is but she refused it and told us off then for trying to help her.

She made her choices and she needs to own them. It sounds like your son is still desperate to avoid his dad being in that same situation.