This review article explores the role of branched-chain amino acids (BCAAs) in metabolic health and disease. It highlights the beneficial effects of dietary restriction on longevity and metabolic health, particularly the reduction in protein intake. The article discusses the metabolic pathways of BCAAs, including their degradation by branched-chain aminotransferase (BCAT) and branched-chain keto acid dehydrogenase (BCKDH), and the regulation of these pathways by transcription factors such as Krüppel-like factor 15 (KLF15) and peroxisome proliferator-activated receptor (PPAR) γ. The review also examines the impact of BCAA catabolism on various tissues, including skeletal muscle, liver, adipose tissue, and the brain, and its implications for diseases such as maple syrup urine disease, heart disease, obesity, insulin resistance, and diabetes. Additionally, the article explores the potential benefits of BCAA-restricted diets in improving metabolic health and promoting healthspan, with a focus on the sex-specific effects and the role of individual BCAAs. The findings suggest that BCAA metabolism plays a crucial role in maintaining metabolic homeostasis and influencing lifespan and healthspan.This review article explores the role of branched-chain amino acids (BCAAs) in metabolic health and disease. It highlights the beneficial effects of dietary restriction on longevity and metabolic health, particularly the reduction in protein intake. The article discusses the metabolic pathways of BCAAs, including their degradation by branched-chain aminotransferase (BCAT) and branched-chain keto acid dehydrogenase (BCKDH), and the regulation of these pathways by transcription factors such as Krüppel-like factor 15 (KLF15) and peroxisome proliferator-activated receptor (PPAR) γ. The review also examines the impact of BCAA catabolism on various tissues, including skeletal muscle, liver, adipose tissue, and the brain, and its implications for diseases such as maple syrup urine disease, heart disease, obesity, insulin resistance, and diabetes. Additionally, the article explores the potential benefits of BCAA-restricted diets in improving metabolic health and promoting healthspan, with a focus on the sex-specific effects and the role of individual BCAAs. The findings suggest that BCAA metabolism plays a crucial role in maintaining metabolic homeostasis and influencing lifespan and healthspan.