I think Michael Winner had the best idea for a diet. He ate the same meals as always, but less of it.
I personally think faddy diets are a waste of time and money.
You will lose more weight if you exercise as well as diet. I realise it's easier said than done at this time of year when the sofa looks so inviting, but only you can supply the will power - no one can help you there.
Don't make the mistake of paying an arm and a leg for gym membership. There are lots of things you can do for free, such as walking, power walking, jogging, cycling etc. There are lots of floor exercises you can do at home, such as sit ups. If you want to tone up your arms/upper body, use things you have in the house, such as tins of food.
Good luck.