Background: General obesity and abdominal obesity is an established risk factor of gastroesophageal reflux disease (GERD). However, the influence of weight or waist change on improvement of GERD is unclear. Our aim was to investigate if weight loss or waist reduction improves GERD symptoms and esophagitis. Methods: A retrospective longitudinal study of 15295 subjects who underwent gastroscopy for a health checkup and reported GERD symptoms between 2011 and 2013, and repeated a checkup until 2014 was conducted. The improvement of GERD symptoms and esophagitis according to weight loss (-2, -0.5 to -2kg/m(2) in body mass index [BMI]), waist reduction (-5, -0.1 to -0.5cm) and baseline BMI/waist circumference (WC) categories was assessed using logistic regression. Key Results: Weight loss or waist reduction was associated with improvement in GERD symptoms only in subjects with general or abdominal obesity. Among subjects with general obesity (BMI 25kg/m(2)) and decreased 2kg/m(2) in BMI, the adjusted odds ratio (OR) of improvement in GERD symptoms was 2.34 (95% confidence interval [CI] 1.70-2.83). Among subjects with abdominal obesity (WC 90cm) and decreased 5cm in WC, the corresponding OR was 2.16 (95% CI 1.56-2.90). There was no association between weight loss or waist reduction and improvement in esophagitis. Conclusions & Inferences: Weight loss or waist reduction was associated with improvement in GERD symptoms only in subjects with general or abdominal obesity. Weight loss or waist reduction will be an important treatment option in obese patients.