Jennifer Aniston loves it. Gwyneth Paltrow can't get enough of it. High in protein, gluten-free, packed with amino acids, fibre, magnesium, calcium, Vitamin B6 and Omega 3s, and with a low GI that keeps you fuller for longer, quinoa is the fitness food for 2013 that everyone's talking about (the UN has even declared it the International Year of Quinoa!).