What you get for 400 calories

5oz lean grilled fillet steak, oven chips and salad
402 calories, 14g fat
Steak and chips doesn't have to be fattening. Just trim off all the fat and keep an eye on portion sizes for a healthy and slimline dinner.

Pack of Walkers Big Eat crisps, 41p, and a glass of wine
Total: 408 calories, 18g fat
Here's the reason why an attack of the late evening munchies can be so damaging. Just one glass of wine and a 55g bag of crisps will cost you the calories of a proper meal. 289 calories come just from the crisps.

Baked potato with canned salmon and watercress
394 calories, 8g fat
Rich in omega-3 oils for a healthy heart and brain. But don't top with mayo, it's high enough in calories without that.

Sainsbury's Be Good to Yourself Lasagne
422 calories, 8g fat, £1.49
Not all ready meals are a diet disaster, but you'll generally have to choose the lower fat ones to get a meal for 400 calories or less. Add lots of salad or boiled or steamed veg to make it healthy.