( ( Counting calories ) ( ( A calorie ) ( ( is ( ( a unit ) ( of ( measurement ( used ( to ( express ( ( the ( energy value ) ) ( of food ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (VBG Counting) (NP (NNS calories))) (NP (DT A) (NN calorie)) (VP (VBZ is) (NP (NP (DT a) (NN unit)) (PP (IN of) (NP (NP (NN measurement)) (VP (VBN used) (S (VP (TO to) (VP (VB express) (NP (NP (DT the) (NN energy) (NN value)) (PP (IN of) (NP (NN food)))))))))))) (. .)))
Counting calories A calorie is a unit of measurement used to express the energy value of food.
(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.