( ( ( ( ( ( A ( 100-calorie serving ) ) ( of grapes ) ) , ) ( ( a food ) ( ( ( low ( in ( energy density ) ) ) and ) ( high ( in ( water content ) ) ) ) ) ) , ) ( ( is ( one ( and ( two ( thirds cups ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (DT A) (JJ 100-calorie) (NN serving)) (PP (IN of) (NP (NNS grapes)))) (, ,) (NP (NP (DT a) (NN food)) (ADJP (ADJP (JJ low) (PP (IN in) (NP (NN energy) (NN density)))) (CC and) (ADJP (JJ high) (PP (IN in) (NP (NN water) (NN content)))))) (, ,)) (VP (VBZ is) (NP (CD one) (CC and) (CD two) (NNS thirds) (NNS cups))) (. .)))
A 100-calorie serving of grapes, a food low in energy density and high in water content, is one and two thirds cups.
(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.