This review discusses the effects of dietary fiber and its components on metabolic health. Dietary fiber and whole grains contain bioactive components such as resistant starches, vitamins, minerals, phytochemicals, and antioxidants. Epidemiological and clinical studies show that higher dietary fiber intake is inversely related to obesity, type 2 diabetes, cancer, and cardiovascular disease. Dietary fiber is defined as edible plant parts or similar carbohydrates resistant to digestion in the small intestine. It can be separated into fractions like arabinoxylan, inulin, pectin, bran, cellulose, β-glucan, and resistant starch. These components may help reduce disease risk through mechanisms such as intestinal viscosity changes, nutrient absorption, short-chain fatty acid production, and gut hormone regulation. However, study inconsistencies exist, so this review examines the latest data on dietary fiber and metabolic health. Dietary fiber is classified as non-structural carbohydrates (NSP) or structural carbohydrates (NSP). The American Association of Cereal Chemists defines dietary fiber as carbohydrate polymers with more than three monomeric units not digested in the small intestine. The World Health Organization and Food and Agriculture Organization agree with this definition but with slight variations. Dietary fiber includes non-starch polysaccharides, oligosaccharides, and resistant starches. Dietary fiber may help reduce obesity by decreasing energy absorption, increasing satiety, and reducing calorie intake. It may also help prevent type 2 diabetes by improving glucose metabolism, reducing postprandial glucose levels, and increasing insulin sensitivity. Soluble and insoluble fibers have different effects on weight management and diabetes risk. Soluble fiber may lower glucose and insulin levels, while insoluble fiber may reduce nutrient absorption and increase passage rate through the gastrointestinal tract. Key dietary fiber components include arabinoxylan, inulin, β-glucan, pectin, bran, cellulose, and resistant starch. Arabinoxylan may improve glucose tolerance by increasing intestinal viscosity. Inulin may improve mineral absorption and reduce cholesterol levels. β-glucan may lower cholesterol and improve glucose metabolism. Pectin may reduce cholesterol and improve gut health. Bran may lower cholesterol and improve glucose control. Cellulose may reduce calorie intake and improve glucose metabolism. Resistant starch may lower glucose and insulin levels. Overall, dietary fiber and its components may have beneficial effects on metabolic health, but more research is needed to fully understand their mechanisms and optimal use.This review discusses the effects of dietary fiber and its components on metabolic health. Dietary fiber and whole grains contain bioactive components such as resistant starches, vitamins, minerals, phytochemicals, and antioxidants. Epidemiological and clinical studies show that higher dietary fiber intake is inversely related to obesity, type 2 diabetes, cancer, and cardiovascular disease. Dietary fiber is defined as edible plant parts or similar carbohydrates resistant to digestion in the small intestine. It can be separated into fractions like arabinoxylan, inulin, pectin, bran, cellulose, β-glucan, and resistant starch. These components may help reduce disease risk through mechanisms such as intestinal viscosity changes, nutrient absorption, short-chain fatty acid production, and gut hormone regulation. However, study inconsistencies exist, so this review examines the latest data on dietary fiber and metabolic health. Dietary fiber is classified as non-structural carbohydrates (NSP) or structural carbohydrates (NSP). The American Association of Cereal Chemists defines dietary fiber as carbohydrate polymers with more than three monomeric units not digested in the small intestine. The World Health Organization and Food and Agriculture Organization agree with this definition but with slight variations. Dietary fiber includes non-starch polysaccharides, oligosaccharides, and resistant starches. Dietary fiber may help reduce obesity by decreasing energy absorption, increasing satiety, and reducing calorie intake. It may also help prevent type 2 diabetes by improving glucose metabolism, reducing postprandial glucose levels, and increasing insulin sensitivity. Soluble and insoluble fibers have different effects on weight management and diabetes risk. Soluble fiber may lower glucose and insulin levels, while insoluble fiber may reduce nutrient absorption and increase passage rate through the gastrointestinal tract. Key dietary fiber components include arabinoxylan, inulin, β-glucan, pectin, bran, cellulose, and resistant starch. Arabinoxylan may improve glucose tolerance by increasing intestinal viscosity. Inulin may improve mineral absorption and reduce cholesterol levels. β-glucan may lower cholesterol and improve glucose metabolism. Pectin may reduce cholesterol and improve gut health. Bran may lower cholesterol and improve glucose control. Cellulose may reduce calorie intake and improve glucose metabolism. Resistant starch may lower glucose and insulin levels. Overall, dietary fiber and its components may have beneficial effects on metabolic health, but more research is needed to fully understand their mechanisms and optimal use.