I think you just have to bluntly approach him. He’s old enough that beating around the bush isn’t likely to get you anywhere.

I wonder if your son still lives at home and what type of relationship you have with him ?
I’m a vegetarian myself since I was 11yrs old (now 54yrs old) and when I was young it caused a lot of joking and I was not taken serious in our family. Till the day of today my parents and sisters don’t understand my different opinion about food. When I was younger I felt misunderstood and always had the feeling I had to defend myself. Three of my kids are vegetarian and one of them has also a sensitivity to diary products, so is pretty much vegan (she eats however eggs and honey). A vegetarian diet is quite healthy, a vegan diet requires a bit more attention in regards to intake of all vitamins and minerals, but can still be a healthy lifestyle. I wouldn’t be to concerned about the amount he eats. Now a days many people over consume and it’s proven to be healthier to be a bit more moderate.
In regards to hygiene, some vegans ddon’t like to use body care products with chemicals and harsh soaps and believe that removing of the natural body oils isn’t a good choice. It might be good to check out with your son what his thoughts are about this. A nice and pure alternative can be soap nuts ( you can wash your body, hair, kitchen and laundry with it).
Given his age (he is an adult) I would just have a chat with him to find out what his thoughts are (not to teach him or directly speak out your concerns).

Maybe write him a letter since it can be hard to talk face to face especially to an adult, but be prepared to realize vegan is actually far healthier than what most people are eating, that eating “little” (calorie restriction) is actually proven to increase life expectancy.. so dietwise he is doing all the right things for a long healthy fulfilling life.. (might need Vitamin B12 top ups is the only suggestion with non-animal diets). so I wouldn’t be worried about his nutrition at all… and maybe congratulate him for his excellent choices…. but write and tell him your worries if it is important to you. Hygiene is more of an issue and while male standards might be different to yours if he is lice infested, or covered with some bad skin disease etc. then he probably does need some guidance… if he just smells then might not be worth stressing about, but again maybe write since open communication is the goal to aim for with the aim of building relationships (not necessarily changing another person).

If you know any of his friends and can trust their confidentiallity, can you speak to them and see if they have noticed the same issues. They may be able to bring it up in conversation with him. One of them may be more successful and ideas respected more coming from a person nearer his age. I am only stating this as I know other families that have had issues. Even if he was living at home, getting them to remove their sheets from their beds and showering for clothes to go in the washing can be a trial. Been a few disagreements with kids here too.

Your son probably made a choice that meat is not a choice and have chosen to live his own lifestyle which you may not approve of . I am a direct person and being a mother if there is a concern , it should be brought up . Maybe sit down together when you have a chance and normally when I talk to my kids I start of with , I’d like to discuss /talk about something …..

I would come straight out and tell my kids if they had a hygiene problem. We are very close and I feel I can tell them almost anything. I’m sure they would appreciate being told, bad personal hygiene can drive people away

There are so many options for vegans now, with food and with toiletries….. Google is great!

Perhaps he doesn’t eat much because there’s very little there for him to eat? Is he interested in doing his own shopping? There’s a whole world of vegan-friendly products out there now, not like when I was veg at that age. It’s better just to buy whole foods fresh & cheap & make everything from scratch. Does he have any vegan friends? There are some great vegan ‘dining out’ groups now – at least one in every capital city… that should take care of hygiene issues too!

Tell him he will never get a GF if he continues not to shower.

I know someone that doesn’t have good hygiene and when we say something he gets mad so i don’t really have anything useful

he is your Son, just be upfront and honest and tell him he needs to take a tub

I’m sorry he’s 21, let him figure it out for himself

Tricky… he is an adult… maybe just straightforward???

Firstly I don’t believe in being a vegetarian or vegan UNLESS you make sure you are receiving the proper nutrients…… I would approach the topic by showing that your on his side……”So I understand that eating a vegan diet is important, what sort of meals can I cook that you’ll enjoy but also are really healthy” Make it a Mum and son thing, to cook vegan meals that are super healthy. If not force him into a blood test, guarantee his iron will be dangerously low,

perhaps teach him one or two simple yet nutritious meals he can do for himself or give him a gift of some vegan cooking lessons if you don’t want to do the teaching. you can also explain to teacher too if she can touch on the subject of hygiene too.

At 21 years of age you would think he would be trying to impress the people around him! It is time for his personal hygiene to improve & maybe gifts on his birthday & Christmas dealing with good hygiene products will work.

Ask him what he uses as you were thinking about being more animal friendly. Then look up some vegan products yourself and take them to him, saying you e tried them and love them

Not easy, if you find you can’t approach him about it, how about buying him a book or two as a present. There are quite a few good books on the topic, you could also read the book and tell him you thought he might be interested as they’re are some good tips on….and tell him some to get him interested. Just a though.

I think you just need to sit him down and be honest with him i know how hard it is talking to older kids i have an 18 year old son and i just find being honest and open with him is the best way to be.
If i don’t think he’s showering enough or eating the wrong foods i just say so and give him advice on how to change what he’s doing.
Good luck

Mel1 is right. If he is not looking after his hygiene is he also doing the same with food – perhaps being non conscious of all the vitamins he needs that often aren’t readily available in a vegan diet unless you are very aware of exactly what foods you are eating to get enough iron and vitamin b. The hygiene one is tricky. I like another mums idea of approaching it in a joking kind of way but with a semi serious overtone about job prospects and partners etc. it’s hard because he is 21. I hope it’s just a phase. Perhaps show him some litterature from healthy eating sites etc. The better health channel is a great website.