( ( 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 (NP (DT The) (NN energy) (NN content)) (PP (IN of) (NP (NNS foods)))) (VP (VBZ is) (ADVP (RB often)) (VP (VBN expressed) (PP (IN in) (NP (NNS calories))))) (. .)))
The energy content of foods is often expressed in calories.