( Calories ( ( ( The energy ) ( in food ) ) ( ( is ( called calories ) ) . ) ) )
(ROOT (S (ADVP (RB Calories)) (NP (NP (DT The) (NN energy)) (PP (IN in) (NP (NN food)))) (VP (VBZ is) (VP (VBN called) (NP (NNS calories)))) (. .)))
Calories The energy in food is called 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.