How do you tell a loved one that they need to loose weight

You can’t. Unless they bring up the subject first however you try to raise the matter you are bound to upset them. No one likes to be criticised and that’s basically what you will be doing. You don’t like the way they are living their life. You don’t like the food they are eating. You don’t like the fact they have put on weight.

Is there an underlying problem or is it simply ignorance (a young person fending for themselves for the first time)? Tackle either those aspects and you’re half way there. But remember the person won’t thank you for your kindly meant advice unless they asked for your help first.

You can't. I told my D how I felt about her weight and lifestyle and pointed out that until she wanted to do it for herself and no-one else it was a lost cause.
She is now trying after many years and a broken marriage which I feel was significant.

Impossible , sorry to be blunt . Unless they ask your opinion about it , even then choose your words carefully . These days with all the TV programmes and stuff on line , in Magazines and Newspapers , the are unlikely to be unaware of their problem .