600 calories of vegetarian fare.
We're on a 5-2 diet. You eat whatever you want for 5 days, interspersed with 2 'semi-fasting' days of 600 calories. Supposed to have all sorts of benefits, like lowering long-term blood glucose levels, and others, and losing weight (well, you're having a few thousand calories less per week, so it would).
It's easier than most diets as you know that tomorrow you can EAT, so you've only got to put up with this for a day. And no, you don't jump out of bed the next morning and have an enormous breakfast! Well, we don't.
Watch it if you're in doubt or on the sort of medications that need larger quantities of food - ask a doctor or trusted nurse.
Got the idea from a Horizon programme on BBC a few weeks back.
A.