( ( calorie ( ( A unit ) ( of ( measure ( of ( ( the amount ) ( of energy ) ) ) ) ) ) ) ( ( a food ) ( ( will ( produce ( when ( it ( is consumed ) ) ) ) ) . ) ) )
(ROOT (S (S (VP (VB calorie) (NP (NP (DT A) (NN unit)) (PP (IN of) (NP (NP (NN measure)) (PP (IN of) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN energy)))))))))) (NP (DT a) (NN food)) (VP (MD will) (VP (VB produce) (SBAR (WHADVP (WRB when)) (S (NP (PRP it)) (VP (VBZ is) (VP (VBN consumed))))))) (. .)))
calorie A unit of measure of the amount of energy a food will produce when it is consumed.
(ROOT (S (NP (DT A) (NN calorie)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB express) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN energy)))) (PP (IN in) (NP (NN food)))))))) (. .)))
A calorie is used to express the amount of energy in food.