Calories (kcal)

Calories are a unit of energy used to quantify the fuel provided by macronutrients—carbohydrates, fats, and proteins—during metabolic processes (NIH, 2023). In a biological context, calories are not a specific molecule, receptor, or enzyme, but rather a measure of the chemical energy released through cellular respiration and utilized for physiological work (WHO, 2021). Caloric balance, the ratio of energy intake to energy expenditure, is a critical factor in human health and the primary driver of metabolic disorders such as obesity and type 2 diabetes (StatPearls, 2023). Many therapeutic strategies aim to manage this balance by reducing appetite, increasing satiety, or blocking the absorption of energy-dense molecules like lipids. Because calories represent the net result of various metabolic pathways, they serve as a key metric for assessing the efficacy of weight management and metabolic drugs, even though they do not constitute a druggable target in the traditional sense.

Other names

Energy intakeDietary energyKilocaloriesFood energy

Pharmacological agents do not bind to calories; instead, they modulate physiological processes such as appetite signaling (e.g., GLP-1 receptor agonism), nutrient absorption (e.g., lipase inhibition), or metabolic rate to influence the body's net energy balance (FDA, 2023).