Mariah Carey showed off her sexy new figure in a red hot dress at the Noble Gift Gala at the very posh Dorchester Hotel in London. The star lost about 30 kg in the last seven months, and she looked festive and fabulous in a red floor length dress.  She was the guest of honour at the event and received the 2011 Noble Gift Humanitarian Award for her efforts in helping disadvantaged children. Following her impressive weight loss, Mariah has been named as the new ambassador for diet company Jenny Craig. She began her diet with a 1500 calorie a day special menu and exercises three times a week. "When I started, I got really strict with myself," she told Us magazine. "Losing weight is about eating what you like, just in the appropriate portion sizes, I wouldn't say it was really hard, but it required focus and determination."