Objective To provide a diet management system scheme for sub-obese people and improve their self-efficacy cognition and self-behavior ability in diet management. Methods According to the FBM behavior analysis framework, the diet management behavior of sub-obese people was divided into three stages. From the generation of diet management consciousness, the generation of diet management behavior and the maintenance of diet management behavior, we can gain insight into the behavioral pain points and specific needs of sub-obese people. Then, from three aspects: enhancing users’ motivation, improving users’ ability and increasing trigger mechanism, the framework of diet management persuasion strategy for sub-obese people is constructed, and on this basis, the system design scheme is put forward. Conclusion The dietary management behavior based on persuasion theory, through introducing the dietary management product system, is beneficial to improve the cognition of self-dietary management of sub-obese groups and guide them to realize the benign transformation of dietary behavior.