Counting calories: yes or no?

Hand eating cake

There's no shortage of advice when it comes to diet and weight loss; in fact, it's an industry that was recently valued at £2 billion in the UK alone. From diets that claim to help you shift multiple pounds in one week, to the pills and potions that promise to get you the body you want, there seems to be a helping hand at every corner, waiting to take your money. So, what actually works?