The `In Time` actress always gets her legs out when attending glamorous events because they`re her best feature so doesn`t want to cover them up.
She said: "No matter how much I`ve eaten and how little I`ve exercised, my legs will always be tiny and I don`t have any cellulite - yet! So trust me, you`ll never see me in trousers on the red carpet."
Amanda, 25, also says she`s quite sensible with her diet and exercise and doesn`t really deprive herself.
In an interview with Glamour magazine, she said: "When my belly fat goes away I`m happy and I`d love to have a six-pack one day but that would meaning eating a little less pasta. Basically, there`s no big mystery; we`re all smart enough to know what works and what doesn`t."
The blonde beauty also admits she`s becoming more aware with how she`s ageing, saying: "Living in a society where there`s so much attention given to age-defying products, I`m really aware of how my face is changing, even at my age."