The World Health Organization has documented the impact that a balanced diet has on disease prevention. Overconsumption of meat can lead to obesity, arteriosclerosis, thrombosis, type 2 diabetes and many life-threatening diseases. A new group of proteins has currently emerged in the scientific community of alternative nutrition called “alternative proteins”. Several interventions have been introduced by a large number of healthcare providers in order to promote and enhance people’s dietary habits. Two of the most prevalent models of health-related behaviour modification are the transtheoretical—stages of change—model (TM) and motivational interviewing (MI). The purpose of this study is to research and examine how the ΤΜ and MI could be effectively implemented in the diet of health professionals through alterations of eating habits. The population of the study is to comprise health professionals from «AΤΤΙΚOΝ» University General Hospital, Athens, Greece. The sample of participants is to be selected by the professional environment of the researcher. Participants, through random selection, are to be divided into two groups: the control group, consisting of 50 individuals, and the intervention group, consisting of 50 individuals. The duration of the study is to be from November 2022 to November 2024. The present study is concerned with productive mixed—quantitative and qualitative—evolutionary research along with the application testing of both the ΤΜ and the MI. It is to be conducted specifically on health professionals via self-administered questionnaires and semi-structured interviews.