This study investigates the association between body mass index (BMI) and the risk, age of onset, and overall survival of patients with pancreatic cancer. The study included 841 patients with pancreatic adenocarcinoma and 754 healthy controls frequency matched by age, race, and sex. Individuals who were overweight (BMI 25-29.9) from ages 14 to 39 years or obese (BMI ≥30) from ages 20 to 49 years had an increased risk of pancreatic cancer, independent of diabetes status. The association was stronger in men and ever smokers. Being overweight or obese from ages 20 to 49 years was associated with an earlier onset of pancreatic cancer by 2 to 6 years. Obesity at older ages was associated with reduced overall survival in patients with pancreatic cancer. The findings suggest that excess body weight, particularly in early adulthood, is a significant risk factor for pancreatic cancer and influences disease progression and survival.This study investigates the association between body mass index (BMI) and the risk, age of onset, and overall survival of patients with pancreatic cancer. The study included 841 patients with pancreatic adenocarcinoma and 754 healthy controls frequency matched by age, race, and sex. Individuals who were overweight (BMI 25-29.9) from ages 14 to 39 years or obese (BMI ≥30) from ages 20 to 49 years had an increased risk of pancreatic cancer, independent of diabetes status. The association was stronger in men and ever smokers. Being overweight or obese from ages 20 to 49 years was associated with an earlier onset of pancreatic cancer by 2 to 6 years. Obesity at older ages was associated with reduced overall survival in patients with pancreatic cancer. The findings suggest that excess body weight, particularly in early adulthood, is a significant risk factor for pancreatic cancer and influences disease progression and survival.