The first challenge here may be that your friend is feeling a little miffed that you have changed.
Change is not only hard when it affects us personally, it can also be hard for your friends to accept.
They may even be feeling a bit jealous that you are managing to make a healthy choice when they have not.
I encountered quite a bit of resistance from some of my friends, others were interested and wanted to know more.
If the host is not a close friend, be sure to let them know in advance what you are and are not happy to eat.
Be flexible, let them know that you do not expect them to cook to meet just your requirements, that you are happy to skip the dishes that do not suit you, but that you would like them to let you know which dishes are OK for you and which are not.
Think back to when you were first changing your diet and how difficult it seemed to be to know what to eat.
If your host is a meat eater, they may have no idea how to put together a vegetarian meal.
With closer friends, you may need to be firm.
Close friends may try to get around you with such statements as "it's only got a bit of cream/meat/cheese in it, will that be ok?" Politely, but firmly, say no.
Tell them you are happy to skip the main dish and have the side dishes, salad and bread.
Offer to bring something that can be warmed up, to substitute as your main dish.
This also offers a bit of a talking point as others will want to know what you are eating and why, and many people are interested to know about eating healthily, just be careful not to overdo the advice unless it has been requested! The other potential stumbling block is when your host realises at the last moment that her carefully prepared vegetable soup was actually cooked using a meat stock.
She probably didn't even think about it, as this is what she always does.
You have a choice, decide to eat it, or just have a nice fresh bread roll while the others eat the soup.
I would go for the bread roll option, if you waver this time, the next time she will think you will waver for something else.
If you just eat the bread roll, she will remember that and the next time will think through her ingredients more carefully.
Last summer I met up with an aunt who I had not seen for 40 years.
My son and I stayed with her.
On the first evening we ate out, so I ordered a vegetarian option on the menu, without mentioning being vegetarian.
On the second evening she said she would like to cook a meal for us all, so I told her that would be lovely, but that I did not eat meat.
No problem, she said, she was vegetarian too! She also told me that my grandfather had been a vegetarian, something I was totally unaware of until then.
The other side of the dinner party dilemma is what to do when you have invited friends to come to your place for dinner.
It is up to you of course, but I like to introduce my friends to my best vegetarian recipes.
It is an opportunity to show them that vegetarian food can be very tasty as well as healthy and nutritious.
One of my favourite lunches to prepare for friends is a simple platter of vegetables and dips, with some lovely fresh seeded wholemeal bread rolls, followed by fresh fruit.
It is no fuss, simple and delicious and let's your friends see that what you like to eat is not weird! It is good to put something a little unusual out too, perhaps some freshly cooked beetroot, some seeds you have sprouted yourself, some sauerkraut, coriander or other fresh herbs, or a lentil dip.
This will let your friends know that there are new things to explore in a vegetarian diet.
Once you start on your healthy eating you will be amazed how many options there are and what a huge range of recipes are available for you to try.
When people ask what I eat, I always say if you eat all the things you are supposed to eat in a day to stay healthy, you won't have room for anything else! Happy healthy eating!