What is fatty tissue called?

Fatty tissue is called adipose tissue, a specialized connective tissue that stores energy as fat (triglycerides), provides insulation against heat loss, cushions and protects organs, and secretes hormones regulating metabolism and appetite.

Adipose tissue consists of cells called adipocytes (fat cells) that store triglycerides in large lipid droplets, making fat cells appear large and round with the nucleus pushed to one edge. Between adipocytes exists extracellular matrix containing blood vessels (supplying nutrients and removing metabolic waste) and nerve fibers. Adipose tissue exists in two main forms with different characteristics and functions. White adipose tissue represents the most abundant type, appearing yellowish-white and serving primarily for energy storage—it accumulates under skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow, and in other locations. White adipose tissue also secretes hormones including leptin (regulating appetite and metabolism), adiponectin (enhancing insulin sensitivity), and various inflammatory signaling molecules. Brown adipose tissue, more common in infants but present in small amounts in adults (particularly around neck and upper back), contains numerous mitochondria giving it brown color and specializes in heat generation through a process called thermogenesis, burning stored fat to produce warmth without shivering. Recent research identified "beige" adipose tissue, which can develop from white adipose tissue and exhibit some brown adipose tissue characteristics. Adipose tissue distribution affects health—excess visceral fat (around organs) increases risks for diabetes, cardiovascular disease, and metabolic syndrome more than subcutaneous fat. Healthy adipose tissue is essential, providing energy reserves, thermal insulation, and hormone production, but excessive accumulation or very low levels both pose health risks. Understanding adipose tissue helps inform healthy weight management, recognizing that moderate, well-distributed body fat supports health while excessive or deficient levels require intervention.