Database: synthea
Question: List out 5 most common conditions for underweight patient.
SQL: SELECT DISTINCT T2.DESCRIPTION, T2.VALUE, T2.UNITS FROM patients AS T1 INNER JOIN observations AS T2 ON T1.patient = T2.PATIENT WHERE T2.DESCRIPTION = 'Body Mass Index' GROUP BY T2.VALUE ORDER BY COUNT(T2.VALUE) LIMIT 5