Meat and fish are important animal-derived foods that have been recognized for their high nutritional density, biological value, and contribution to human growth, repair, and maintenance of body tissues. They provide a concentrated source of complete proteins, essential fatty acids, vitamins, minerals, and other bioactive compounds that play significant physiological roles in metabolism and health. The composition and nutritive value of meat and fish can vary depending on species, age, diet, cut, processing, and cooking method, yet both foods remain major components in balanced diets across different cultures. The composition of meat primarily consists of water, proteins, fat, minerals, and small quantities of carbohydrates. On average, fresh meat contains approximately 65–75% water, 15–20% protein, 2–15% fat, and about 1% minerals. The amount of fat varies significantly between red meat such as beef and lamb and leaner meats like poultry. Meat proteins are of high biological value because they contain all essential amino acids in appropriate proportions necessary for cellular growth and tissue repair. Myofibrillar proteins such as actin and myosin contribute largely to muscle contraction and structure, while sarcoplasmic proteins include enzymes and pigments such as myoglobin responsible for the red color of meat. Proteins in connective tissues, such as collagen and elastin, influence texture and tenderness and change during heat treatment when collagen converts into gelatin, improving digestibility. The fat component in meat is mainly composed of triglycerides stored around muscles and between fibers. Meat fat contains both saturated and unsaturated fatty acids. The proportion varies depending on animal species and feeding practices. Beef and lamb contain more saturated fats, while pork and poultry have comparatively higher monounsaturated fats. Cholesterol is present but in moderate quantities and plays essential biological roles such as hormone synthesis. Meat also contains small amounts of phospholipids that are structurally important for cell membranes and rich in polyunsaturated fatty acids. Carbohydrates in meat are minimal, usually below 1%, primarily in the form of glycogen, which breaks down after slaughter. Although present in small amounts, glycogen contributes to the development of flavor and tenderness during meat ageing. Meat provides essential minerals including iron, zinc, phosphorus, selenium, and potassium. The iron in meat is largely heme iron, which is highly bioavailable and more efficiently absorbed by the human body compared to non-heme iron from plant sources. Vitamins