This project has a parallel randomized controlled experimental design since within the methodology there will be a control of the conditions under study, that is, the selection of subjects, the way the treatment will be administered, the way in which the observations will be obtained, the use of instruments to perform the measurements and the interpretation of the criteria will be implemented in a homogeneous manner.

Convenience sampling was used to obtain the subjects for the study, the sample size was 34 bariatric patients from a private bariatric center in Tijuana, Baja California, Mexico.

Participants were randomly assigned to one of two groups. The group understudy or experimental or the control group on the waitlist; that is, no researcher or study participant made the decision of treatment that participants receive. The intervention consists of two psychoeducative sessions and five cognitive dissonance sessions. All participants will receive the same multivitamin for the duration of the study. Validated tests for adherence, medication knowledge, self-care, self-efficacy, and psychopathological symptoms were applied to both groups. Additionally, a blood sample was collected for the determination of Hemoglobin, Iron, Copper, Zinc, Calcium, Phosphate, Vitamin D, and Folate. Measurements using tests and blood samples will be made before and after receiving the intervention [pre and post-test]. For results analysis, Repeated measures ANOVA will be used, the study population shall be stratified into subgroups, by type of bariatric surgery, age, and sex; this in order to restrict comparisons to participants who are part of the same subgroup.

The aim of the study is to assess the impact of an intervention based on the cognitive dissonance theory to promote adherence to the bariatric multivitamin.

The hypothesis of the study is: Participants exposed to Festinger's theory-based intervention will exhibit changes in their attitude and behavior towards multivitamin intake as a product of cognitive dissonance.

According to the World Health Organization (WHO), in 2016, 650 million people around the world were already obese, for their part in 2013 the Organization for Economic Cooperation and Development (OCDE) indicated that globally Mexico and the United States had the highest rate of overweight and obesity in adults. Mexico is the second country, after the United States, with the highest obesity, almost one third of Mexican adults (32.4%) suffered from obesity in that year, a significant increase from 24% in 2000.

According to the National Health and Nutrition Survey the states of northern Mexico, as is the case of Baja California, occupy the first places of obesity index nationwide. Morbid Obesity (MO) poses a high health risk in those who suffer from it, as multiple complications arise from it, therefore it is of uttermost importance that this disease is successfully treated and controlled, however, conventional weight loss therapeutics guided by the implementation of behavioral therapy, physical activity, low calorie diet and drug treatment , has shown short-term unsuccessful results. A treatment alternative is Bariatric Surgery (BS) which, according to recommendations issued in 1991 by the U.S. National Institutes of Health (NIH), is considered the treatment of choice for this pathology. While BS has proven to be a successful treatment for long-term sustained weight loss, it is accompanied by major complications such as micronutrient deficiency, which is attributed to intrinsic and extrinsic factors, intrinsic factors refer to deficiencies recorded prior to BS and are related to MO or to the surgical technique itself that induces changes in metabolism in addition to reducing the ability to food in the stomach, limit digestion and cause malabsorption. For their part, extrinsic factors correspond to the lack of adherence in terms of diet and prescribed multivitamin supplementation.

Lack of adherence is related to the level of knowledge about the supplementation and behavior of the morbid patient on decision-making, as they tend to present negative thoughts about the prescribed treatment that are usually accompanied by lack of ability to make changes in both attitude and behavior, which will hardly change even after surgery; this is consistent with the results reported in various studies that indicate that the main behavioral factors of non-adherence to treatment in this population are the low self-efficacy and attitudes that the patient adopts towards treatment on self-care, as well as low self-esteem and distortion of self-concept.

As described, BS can be considered a process of adaptation that can pose a challenge for those who experience it as the person must be aware of the impact of surgery on the body in order to effectively adhere to the agreed treatment plan, making decisions in conjunction with health professionals in order to reduce risk factors , focusing therefore on prevention and timely intervention of them.

In this sense, psychology turns out to be a science that allows to develop instruments that evaluate the congruence between attitudes, thought and behavior, as well as the creation of strategies that promote health promoting the congruence between attitude and behavior. Leon Festinger in 1957 proposed the theory of Cognitive Dissonance, which states that people tend to change their attitudes and behaviors or justify them as a result of the divergence of two cognitions manifested at the same time; according to this theory, the individual strives to achieve consistency within himself. Opinions and attitudes tend to be present in groups that are internally consistent.

Population:

POST-operated Bariatric Surgery patients

Sample:

Post-Bariatric Surgery patients who permanently radiate in the Tijuana Co.

Sampling type:

In the first time, non-probabilistic, convenience sampling for the selection of participants and in a second time for randomization stratification will be performed.

Sampling site:

One private bariatric center in Tijuana, Baja California, Mexico. Research plan

1. Submission and approval of the research protocol to the bioethics committee of the Faculty of Medicine and Psychology (FMYP) of the Autonomous University of Baja California (UABC)
2. Designing the manuals of psycho-educational intervention and dissonance to promote and improve adherence to the multivitamin prescribed in bariatric patients.
3. Once obtaining the bioethics committee approval, the authorities of a private bariatric center operating patients living in Tijuana were consulted to request their cooperation in conducting the research.

(d) Data collection was carried out through the review of clinical records in accordance with the Mexican Official Norm (NOM) NOM-004-SSA3-2012.

(e) Persons who meet the inclusion criteria were contacted by telephone in order to recruit the participants who were included in the study.

(f) Arrange a face-to-face appointment with the person who decides to participate to sign the document "informed consent (IC)" version 1.0, in order to clarify doubts about the methodology of the project and inform him that his participation is voluntary, that at any time he may withdraw his consent and that the information he provides will be handled confidentially, in accordance with NOM-012-SSA3-2012 on Human Research.

(g) Participants were randomly assigned to the experimental group and control group on the waiting list using the on-line tool GraphPad QuickCalcs.

(h) For the application of the measuring instrument (MI) in order to comply with the recommendations of the WHO derived from the COVID pandemic and maintain social distancing, the MI containing all tests was adapted for a digital application using Google Forms and the group sessions were modified to be video conferences through Google Meet.

(i) For the sessions of cognitive dissonance and psycho-education, Psychology Bachelors were trained and randomly assigned to the cognitive or psycho-educational intervention.

(j) The pre-test and post-test blood samples are taken one day after the application of the MI (before and after the intervention), according to NOM-253-SSA1-2012 for the disposal of human blood.

(k) The determination of biomarkers was carried out according to the NOM-007-SSA3-2011 for the operation of clinical laboratories. The analysis of calcium, phosphorus, and serum iron was carried out within the facilities of the UABC Medical Care and Research Centre (CUMAII) using colorimetric spectrophotometry; The levels of Vit-D and Folate were be analyzed by Enzyme-Linked ImmunoSorbent Assay (ELISA), the quantification of hemoglobin was performed during flow cytometry. For the determination of minerals (zinc and copper) in serum, a collaboration agreement will be held with the Graduate Center of the Tijuana Institute of Technology; the method of analysis will be Mass Spectrometry with Inductively Coupled Plasma (ICP/MS).

(l) The week following sampling, 90-minute online intervention sessions will begin every two weeks for three months. It is important to mention that, before the first online session (second week) the participants of both groups will be given a bariatric multivitamin supplement with 60 chewable tablets, dispensing a new one of the same brand as the first, this in order to cover three months of treatment.

(m) Participants were asked to inform through a phone call to the research team in case of presenting any adverse effects such as nausea, vomit, dizziness, or diarrhea. This will be noted in the corresponding document.

(n) Once the post-test data have been obtained, databases will be developed in the SPSS version 26.0 statistical program for Windows, which will be analyzed by repeated-measures ANOVA in order to evaluate the effect of the intervention on adherence to the Multivitamin evidenced by biomarker levels.

Inclusion Criteria:

• Nationality: Mexican.
• Place of Residence: City of Tijuana.
• Bariatric techniques: Gastric Sleeve or Bypass Roux in Y.
• Time after surgery: at least 6 months.
• Agree to participate voluntarily by leaving it under signature in the informed consent format.

Exclusion Criteria:

• Nationality: foreign
• Patients who do not reside in the city of Tijuana permanently.
• Bariatric techniques other than Gastric Sleeve or Bypass Roux in Y.
• Time: having passed less than 6 months post-operative.
• Patients who have a cognitive disorder that limits learning or attendance at sessions.
• Patients who are suspended by prescription from vitamin consumption.
• Patients with any post-bariatric surgery complications that are under treatment.
• Patients with a history of alcoholism.
• Pregnant patients.
• Patients who practice high-performance exercise.
• Patients who do not consent to participate.

The data obtained from the Measurement Instrument and Micronutrient levels Pre and Post Intervention as well as all the documents and formats used to make this project will be shared with the research teams that contact us via e-mail.

Study data will be available to be requested for five years after the intervention results have been published on an indexed journal.

Researchers that wish to obtain our data must contact us via e-mail and provide evidence of their affiliation and research plan.

Patients will be blindly randomized to one of the two groups and the Cognitive Dissonance doses will be given by two Psychology undergraduate students that are not part of the research team.