Yep it's best to spread it out during the day as keeps your metabolism working. 600 cals for a dinner is quite a lot when you look what you can have, my dinner don't often go near 600 anyway, so 900 wouldn't be needed. Just have a look for the low fat low cal options in the supermarket, either making the meals yourself or the ready meals. You'll be surprised how much you can have. Like tonight I'm going to make a meal for the family of grilled pork chops with boiled potatoes and veg. Mine won't be over 370 cals.