Which of the following is a rich source of energy?

Energy in the human diet is primarily derived from three macronutrients: carbohydrates, proteins, and lipids (fats). While all three provide energy, their energy density varies significantly. Carbohydrates and proteins each provide approximately 4 kilocalories (kcal) per gram [t1, t4, t6]. In contrast, lipids are the most concentrated and rich source of energy, providing approximately 9 kilocalories per gram [t1, t2, t5]. This makes lipids more than twice as energy-dense as the other macronutrients [t1, t5]. Vitamins, categorized as micronutrients, do not provide any energy or fuel in the form of calories; they are instead required in small amounts for vital physiological processes and metabolic regulation [t3, t4]. Therefore, among the given options, lipids are the richest source of energy per unit mass.

Sources

1. [1] https://www.cfs.gov.hk/english/multimedia/multimedia_pub/multimedia_pub_fsf_29_02.html
2. [2] https://www.ncbi.nlm.nih.gov/books/NBK218769/