A 35-year-old man is evaluated for a 2-month history of upper abdominal discomfort after eating. He has recently returned from working in a rural area of a developing country. He takes no medications. There is no family history of esophageal or gastric cancer.

On physical examination, vital signs are normal. BMI is 40. Centripetal obesity is noted, but abdominal examination findings are otherwise normal.

Laboratory studies reveal a hemoglobin level of 15 g/dL (150 g/L).

Which of the following is the most appropriate management?