Which subfield of psychology would most likely promote research identifying the psychological, biological, and social factors that encourage good eating habits?

Answer: Health psychology

Explanation: Health psychology is a study intended at employing a psychological approach in the study, prevention and management of a person's physical health and well being. Health psychology is aimed at understanding how biological, psychological, social, behavioral and cultural factors contributes to a person physical health and disorder

In summary, health psychology encourages consumption of nutrients rich meals, smoking cessation, Regular exercise, good eating habit, good stress management and other contributing factors to good physical health.