Bariatrician: A physician practicing bariatrics, the field of medicine concerned with weight loss. Also called a bariatric physician. The terms are used interchangeably. The American Society of Bariatric Physicians states that: "These guidelines provide suggestions for the work-up and follow-up of the bariatric patient. They are not intended to replace, and indeed cannot replace, the bariatrician's judgment regarding a particular patient's treatment."