Proteins provide 4 calories of energy per gram, fats 9 calories, while carbohydrates 4 calories. A roasted chicken multigrain sandwich which contains 42 g protein,7 g fat, and 34 g carbohydrates will provide a total energy (E) computed as follows:
Let E= 42(4)+7(9)+34(4)
E=168+63+136
E=367 calories of energy
