why do fish and birds have less calories than cows and pigs?

Question

why do fish and birds have less calories than cows and pigs?

In: Biology

Answer 1

Calories come from 3 different substances. Fat, protein, and carbs. Both protein and carbs contain 4 calories per gram and fat contains 9 calories per gram. You can do the math yourself using a nutrition facts label (though nutrition labels have some rounding rules that could have your math off by 2-5 calories).

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So to answer the question, fish and birds are typically less fatty than beef and pork and thus have fewer calories per gram.