Thin privilege is your GP not believing, despite having all your records, that the reason you are the weight you are is more than 6 years of psych drugs, many of which are now the subjects of law suits due to their contribution to obscenely high levels of cholesterol and diabetes. Thin privilege is the ER doc lecturing you on the need for proper diet and exercise, even though you are only in the hospital because of a migraine. Thin privilege is doctors being unwilling to gather all relevant information before passing judgement.