The phrase 'You Are What You EAT' is a proverb that has been around since the early 1900s. It is used to emphasize the importance of eating healthy and nutritious foods in order to maintain a healthy lifestyle. The crossword solution for this phrase is 'EAT', which is a three letter word. This phrase is often used to remind people that what they EAT has an effect on their overall health and wellbeing.