Any one know a really good diete that my parents wont notice?

They hate dietes but I want to lose at least 10 punds by the 20th(camping trip and rodeo, swimming pool birthday ect.)Any good wieght loss products ect?Also does any one have a reccomendation for skin creams to reduce the apearence of cellulitus?I need help ASAP!!!Also how old do you have to be in order to hire a trainer, and about how much in canadian $ does it cost, also for gym memeberships?