Those who say you need to exercise as well are right - dieting by itself may produce initial results but you'll struggle to keep it off. Combining it with exercise will result in more long term results. In fact, you don't necessarily need to diet at all, just eat sensibly (that means cutting down on the chocolates I'm afraid!). And Keep your matabilism high by eating small amounts at regular periods throughout the day, rather than having just three large meals.

As for diet pills, they rarely work so I wouldn't bother with them.