( ( ( The amount ) ( of ( energy ( in food ) ) ) ) ( ( is ( measured ( in calories ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (PP (IN in) (NP (NN food)))))) (VP (VBZ is) (VP (VBN measured) (PP (IN in) (NP (NNS calories))))) (. .)))
The amount of energy in food is measured in calories.
(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.