For weight loss it doesn't really matter. Calories are calories. Eat less calories than you expend and you lose weight.
My PT is a qualified nutritionist.
Will obviously be different for adding lean muscle and increasing weight but I'm not at that stage yet.
Should also caveat this by saying that obviously a healthy diet staying within calories is important however it's good to know that you can have the odd treat here and there and not be tempted to think you've fucked your diet and its game over.
At an estimate I would say I'm eating 3 meals a day and 2 snacks, so 35 'meals a week' and it's healthy for 30 or so. I have 1-2 cheat meals a week and a bag of crisps/dark chocolate every other day which does the job for keeping me motivated to keep going.
Best advice I got was not reaching the 'fuck it' stage after you have a bad meal and continuing it for the next two days. Enjoy the cheat meal and get back on the wagon and go again.