Whether it's gruelling gym classes or green juices galore, they're loud, proud, and letting you know about their new regime whether you've expressed any semblance of interest or not (usually, not).
You love them, but if they tell you one more time how many calories are in your pizza, or that you should go for a run before that cookie, you'll strangle them. Sound familiar? You'll enjoy this...
'Do you even know how many calories are in that latte you're drinking?'
No. I don't. And frankly, I couldn't give a toss.
'Can I just have a bite of that?'
If you want this meal, ORDER IT instead of sneaking your fork onto my plate.
'I've eaten nothing but vegetables for three days.'
I've eaten nothing but chocolate bars and mashed potato, but you don't see me bragging about it.
'You're so lucky that you're comfortable in your own body.'
Code for: 'You're so lucky you don't care that your bum needs its own postcode.'
'Putting sugar in your body is basically just poison.'
Mmm, delicious, delicious poison.
'Do you want to go for a run and earn that slice of cake?'
Um, actually, I want to sit in my chair, eat the cake, and then maybe have a nap.
'I can't eat anything with meat, dairy, gluten or wheat.'
You must be a HOOT at dinner parties.
'Other people have lost four stone in two weeks on this plan!'
And presumably died immediately afterwards, because that couldn't be more unhealthy if it tried.
'I brought low calorie wine!'
Oh, goody. 4% vinegar.
'My Fitness Pal is my new best friend.'
Nice to know we can be replaced BY AN APP.
'Ooh, better post a picture of my salad on Facebook!'
Yeah, I'm sure it'll get just as many likes as my burger.
'God, I look so fat today.'
Here's a rod so you can fish for more compliments.
'You should totally diet with me.'
Mmm, because you're making it look like SO much fun.
Where to next?