It's hard to get enthused about anything when you're depressed.

I smoke pot for depression, but sometimes pot can have the opposite effect from the munchies. I have the bad habit of drinking coffee, smoking cigs, and hopefully (usually, but not lately) smoking pot, and going without food for hours after I first get up, and usually can't make myself eat much till much later.

Of course, the cigs aren't good for appetite. Do you smoke?
Coffee and other stimulants aren't good either.
And too much pot might be a detriment to eating.
Other drugs can hurt your appetite, too.

The big problem with not eating is that it becomes a habit, and your body gets used to it. Try your best to make yourself go ahead and eat. Find something that you really like, and something easy and basic so you don't have to use a lot of effort to fix and cook it. I eat a lot of cheese and bread. I don't put anything else on it, just grab a slice of cheese, 2 slices of bread, and chow down.

Maybe cut back a little on the pot, or make yourself go ahead and eat something before you toke. If you smoke cigs, try to quit or cut down, and you'll probably want to eat to replace the oral fixation and nicotine craving.
If you drink coffee, tea, or othe caffenated drinks, try to cut back.

And take vitamins, particularly B complex, C, and a multi now and then. Down em with some milk, or chocolate milk, or a milk shake. Milk's a great way to drink a little food. A little exercise can help, too. Just a little walk around the hood.

If you still can't eat, and are still depressed, go see a doc, but maybe try a little talk therapy before hitting the pills. See a psychologist (they talk) not a phsychiatrist (they give pills, electro shock, lobotomies, etc.) I'm like you, I don't want to be on some weird chem, and I've avoided anti-deps for over 20 years by using pot. But some folks swear by them, and if nothing else works, they're probably better than dying.

How much is a stone in pounds? (Sorry, ignorant American here.)

Anyway, good luck! And let us know how it goes.