Supplement 1

Interventions

The three different intervention arms are described below according to the guide and checklist of the Template for Intervention Description and Replication (TIDieR) (Hoffmann et al., 2014).

Watch Your Weight During the Holidays Program: This intervention group included self-monitoring strategies (self-weighing, diet monitoring and physical activity), and nutrition counseling and education. The nutritional consultation and education mainly sought to prevent weight gain during the holidays, by reporting nutritional needs according to their body composition, in addition to the use of digital materials that contained information on low-energy menus, “10 tips to lead a healthy lifestyle and how to self-monitor your weight, diet and physical activity.” In addition, participants in this group received a weighing scale to achieve self-monitoring of body weight from the beginning of the study intervention until the end of the 8-weeks follow-up. Participants who completed the 8-weeks measurements received this weighing scale as gift.

The basis of this strategy was the theory of selfregulation. This theory mentions that the change in behavior occurs when the person monitors the current state of their own actions and compares them with a reference goal or “gold standard” established goal (Boutelle, 2006; Orehek et al., 2017). The difference between the two behaviors involves the participant in a “feedback loop”, which adjusts their behavior to achieve the goal (Boutelle, 2006). When the person perceives that there are differences between the current and desired state, they begin to take actions to reduce them. For this, self-regulation obeys two basic processes: 1) The evaluation process, which occurs when the person makes comparisons, and 2) the locomotion process (actions to move forward) (Orehek et al., 2017). Establishing clear objectives is essential in the approach of self-regulation. Once goals are identified, the ability to track behavior, or self-control, becomes essential, as attention to internal and external cues leads to greater control of behavior. Self-monitoring of food intake, physical activity and weight are ways in which the participant can evaluate their own current behavior and compare it with a standard (Boutelle, 2006).

Systematic reviews show that self-regulation can be an effective strategy in preventing body weight gain. Also, they mention that the best way to impact prevention using this technique is with the implementation of low intensity interventions that incorporate face-to-face and non-face-to-face strategies (self-monitoring of weight and nutritional information) (Lemmens et al., 2008; Hutfless et al., 2013; Lombard et al., 2009).

The intervention took place during the last two weeks of the month of November 2021 until the first two weeks of the month of January 2022. During the intervention period, participants were offered one individual and one group Zoom video call session with a maximum duration of 30 minutes for each session, which were led by two of the members of the study staff (DEGM and TJMC). DEGM and TJMC have a bachelor’s degree in Nutritional Sciences as well as a Master of Health Sciences degree. Between November 17 and 19 the participants were contacted in an individual video call to inform them of their assigned group and to give initial instructions about how to perform their self-monitoring strategies (self-weighing, diet monitoring and physical activity monitoring) and receive information about their nutritional status, in relation to their body composition. Also, in this individual session another individual session with a nutritionist was scheduled for one of the first two weeks of the month of January. In the group video call session (November 26) they were trained and given supplementary material with strategies for self-monitoring (body weight, diet, and physical activity), information on healthy lifestyles, as well as information about the energy contained in festive meals and their equivalent in minutes of physical activity or steps per day (Mason et al., 2018). In the case that any participant missed the group videocall session, a link to a video recording of the group session was sent by message via WhatsApp or e-mail.

It was recommended that participants weigh themselves at least twice a week, as a form of self-monitoring of weight, from the beginning of the intervention. Participants had access to weekly formats with boxes where they could fill in the data obtained for each day of self-monitoring of weight, report their energy restriction and minutes of physical activity. In addition, participants were encouraged to restrict the energy they consumed for at least two days of the week, in order to compensate in case that they overconsumed calories (“posadas” or various social meetings, Christmas, New Years, etc.). For this, the participants were informed about the recommended energy consumption according to their needs and were given printed menus with low calorie diets (1200 - 1600 kcal / day) to follow for at least two days of the week.

In the January individual session with the nutritionist, the participants with overweight were not denied weight loss counseling, if they requested it. This counseling used the same intervention pattern as described above. Both the group and individual sessions were implemented in a video call, using Zoom as a video call platform.

During December 7, 21 and January 4 participants had short contact through messages through WhatsApp, telephone texts, calls or e-mail with DEGM to talk about their adherence to the intervention, possible adverse effects that they were experiencing, or any other topic related to this study.

Relative 5:2 Fasting: Participants in this group received eating recommendations to follow 5:2 intermittent fasting. This intermittent fasting approach has been shown to be a potential strategy to avoid weight gain (Harris et al., 2018).

Intermittent energy fasting has two popular variants: 5:2 intermittent fasting and alternate days of fasting. One of the most common strategies is 5:2 intermittent fasting, which involves 5 days of regular food consumption (with ad libitum consumption patterns) exchanged with 2 consecutive or non-consecutive fasting days per week -maximum energy consumption of 500 kcal for women and 600 kcal for men- with a period without energy intake of 12 to 21 hours per day (Harris et al., 2018; Cioffi et al., 2018). In the context of the country where the intervention will take place, a fast, for most people, means not consuming the first meal of the day (breakfast or meal eaten before noon). This intervention group was named Relative Fasting 5:2 (referring to 5:2 intermittent energy fasting), and the participants in this group were able to decide whether their fast was before or after noon.

In studies of the management of obesity, it has been observed that using 5:2 intermittent energy fasting gives a weight loss similar to that obtained with conventional caloric restriction (hypocaloric diets) (Cioffi et al., 2018). In a metaanalysis of studies where intermittent fasting is compared with a group without weight loss treatment, a difference in body weight loss of 4.14 kg ± 2.16 kg (P <0.001) is obtained (Harris et al., 2018).

The mechanism of action of intermittent fasting for weight loss is not only in the pronounced energy restriction on days with calorie restriction, but is also found in the production of ketone bodies in the liver from fatty acids as a result of spending more than 10 hours without energy intake (de Cabo y Mattson, 2019). These ketone bodies are not only used for energy production purposes for some tissues and organs, but also act as powerful signaling agents in cells and functions of different organs. It is believed that one of the functions of ketones is to regulate appetite. However, the mechanism of action remains uncertain (de Cabo y Mattson, 2019; Liu et al., 2020).

This intervention group included one individual session between November 17 and 19 and a group video call session on November 26, with a maximum duration of 30 minutes each. The sessions were led by the same two members of the study committee (DEGM and TJMC).

As in the aforementioned group, during the first individual video call session, participants scheduled an additional individual meeting with a nutritionist for between January 3 and 14.

In the group session the participants received information on how to perform the 5:2 relative fasting. They were given low-calorie menus of 550 kcal and 660 kcal, for women and men respectively, which were to be applied on fasting days, as has been done in similar studies (Cioffi et al., 2018). The composition of the macronutrients in the diet were in accordance with the recommendations of a healthy diet (Great Britain Panel on Dietary Reference, 1991). The fasting was held twice a week and on the remaining five days, the participants did not have any type of energy restriction (it was ad libitum). They only received the general recommendation to adhere to a healthy dietary pattern.

As in the previous intervention group, the individual video call session with the nutritionist followed the group approach (Relative Fasting 5:2). Participants with overweight were not denied weight loss counseling at these sessions if requested. In cases where guidance was requested, it followed the same themes as this intervention group. Both the group and individual sessions were implemented in a video call, using Zoom as the video call platform.

Like the previous group, participants in this group received three short contacts through WhatsApp messages, telephone texts, calls or e-mail with DEGM to talk about their adherence to the intervention, possible adverse effects that they were experiencing, or any other topic related to this study. These short contacts were scheduled for December 8, 22, and January 5.

Control group (minimal intervention): Participants in this group received online information and a PDF file brochure during an individual video call session at the beginning of the 8-week period (from DEGM). This information was about leading a healthy lifestyle. In addition, the brochure contained information on healthy eating based on the Mexican Standard for health promotion and education for healthy eating in Mexico (NOM-043-SSA2-2012) (Norma Oficial Mexicana, 2013). Apart from this, participants in this group did not receive any contact with interventionists in our study. The only additional contact they had with a member of the project committee (DEGM) was to schedule the measurements corresponding to 8 weeks.

Explanation for choosing the comparator

Due to our interest in evaluating the effect, feasibility, and acceptability of two interventions that had not been previously evaluated in terms of their intensity, components and population, the control group received a much less intensive intervention, but with positive components for the health of the participants. In several previous studies in the area, very low intensity interventions have been used as comparators (Mason et al., 2018; Kaviani et al., 2019; Hirsh et al., 2019).

General proceedings and recommendations

The three individual measurement sessions were in person at the Nutrition Health Promotion Center located on the ground floor of the 7J building of the School of Nutritional Sciences of the University of Sonora.

In all interventions, participants were recommended to perform at least 150 minutes of physical activity a week. During the 8-week period, participants in any of the intervention groups were told to avoid following interventions with an effect on body weight unrelated to those in their study group. In case of presenting conditions during the intervention period that required immediate action on body weight, they were not contraindicated but participants were requested to declare them to the project committee. However, during the same 8-week period, they were able to exercise or improve their diet on their own initiative if they so wished (without support from healthcare providers, health professionals, nutritional coaches, personal trainers, etc.). Once the period of measurements at 8 weeks of the participants in each intervention group had concluded, the participants were able to perform any other change or activity with an effect on body weight that could benefit their health. These changes or activities other than the interventions delivered could be made accompanied or not by a health care professional.

Criteria for discontinuing the intervention

Those participants who presented a medical condition or received any treatment that had significant implications on body weight during the protocol, who received any intervention outside the protocol during the 8 weeks of the Holidays, or who decided to abandon the intervention or withdrew their informed consent were discontinued from the intervention.

Program cost

Participants did not pay for the program. Patient materials for intervention sessions or individualized nutrition sessions when applicable were provided free of charge. Participants were only responsible for buying the foods for their diet.

Measurements of the study variables

For all face-to-face measurements, COVID-19 recommendations for medical appointments were followed. For this scenario, WHO suggested collecting all possible data by telephone or other non-face-to-face means. If a visit was necessary, it was recommended to have disinfectant gel, medical or surgical masks for all study participants, respect the distance between people, take care of ventilation and avoid agglomerations (Organización Mundial de la Salud, 2020).

Following the above recommendations, participants were measured for primary and secondary variables using a combination of face-to-face measurements and online forms during the first two weeks of November for baseline measurements. Afterwards, the variables were measured again, following the same recommendations, at the end of the 8 weeks intervention. These measurements were conducted during the last two weeks of January.

For each of the measurements, the participants were required to fast for 8 to 12 hours and to have at least 2 hours without water intake, for body composition and body size measurements, preferably with empty intestines and bladder. In addition, participants were instructed to not perform vigorous physical activity during the 24 hours prior to measurements.

Data collection methods

The study measurements took place during the initial phase, and at 8 weeks at the Nutrition Health Promotion Center (assessed by TJMC) and the Clinical Biochemistry Laboratory of the University of Sonora (obtained by ALMP), by outcome assessors from our research team (blinded to group assignment). Due to the pandemic of COVID-19, the measurements body weight, body size, blood pressure, and collection of the blood sample took place in the Nutrition Health Promotion Center and the Biochemistry Laboratory of the University of Sonora, following the above WHO recommendations for face-to-face medical appointments. The paper forms for health-related quality of life, scales of satisfaction, adherence to intervention and sociodemographic information were obtained in the outdoors space near the Nutrition Health Promotion Center.

Primary measurement

Body weight. It was measured with a digital SECA scale, model 284 (Seca Gmbh & Co. Hammer Steindamm 9-25, Germany, capacity 300 ± 0.05 kg) following a standard technique (Cameron N, 2004).

Secondary measurements

Body fat. Was estimated with a SECA MBCA electrical bioimpedance equipment (Medical Body Composition Analyzer, SECA gmbh & Co. Kg Hammer Steindamm 9-25).

Body size measurements. Height was measured with a SECA stadiometer, model 284 (Seca Gmbh & Co. Hammer Steindamm 9-25, Germany, Capacity 30-220 cm). The waist circumference was measured at the umbilical level with a fiberglass anthropometric tape (GÜLICK, 0 to 150 cm) (Cameron N, 2004).

Blood pressure. Measurement was performed in duplicate using a digital sphygmomanometer (Omrom, model HEM907XL) following the technique proposed by the American College of Cardiology (ACC) / American Heart Association (AHA) (Whelton et al., 2017).

Analysis of biochemical parameters. The biochemical parameters to be measured were the following: fasting glucose, total cholesterol, LDL cholesterol, HDL, triglycerides. The biochemical parameters tests of the study were conducted in the Laboratory of Clinical Biochemistry of Medicine of the University of Sonora using standardized techniques (RANDOX®, Crumlin, UK).

Health-related quality of life. It was evaluated with the SF-36 survey (Zúniga et al., 1999).

Percentage of retention / attrition of participants. The retention percentage was obtained by dividing the people who attended for the 8-week measures among those who started the intervention multiplied by 100. The dropout percentage was obtained by the difference in the number of subjects who started and finished the intervention divided by the number of subjects who started the intervention.

Other measurements

Sociodemographic variables. Sociodemographic variables measured included: age, gender, employment and marital status, educational level and approximate monthly household income. These were measured using a questionnaire through a video call.

Annex 1 references

Boutelle, K. 2006. Weighing the evidence: Benefits of regular weight monitoring for weight control. Journal of Nutrition Education and Behavior. 38, 131.

Cioffi, I., Evangelista, A., Ponzo, V., Ciccone, G., Soldati, L., Santarpia, L., Contaldo, F., Pasanisi, F., Ghigo, E. and Bo, S. 2018. Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: A systematic review and meta-analysis of randomized controlled trials. Journal of Translational Medicine. 16, 371-371.

De Cabo, R. and Mattson, M. P. 2019. Effects of intermittent fasting on health, aging, and disease. The New England Journal of Medicine. 381, 2541-2551.

Great Britain Panel on Dietary Reference. 1991. Dietary reference values for food energy and nutrients for the united kingdom: Report of the panel on dietary reference values of the committee on medical aspects of food policy. Reports of Health and Social Subjects.

Harris, L., Hamilton, S., Azevedo, L. B., Olajide, J., De Brun, C., Waller, G., Whittaker, V., Sharp, T., Lean, M., Hankey, C. and Ells, L. 2018. Intermittent fasting interventions for treatment of overweight and obesity in adults: A systematic review and meta-analysis. JBI Database for Systematic Reviews and Implementation Reports. 16, 507-547.

Hauspie R. C., Cameron N, and Molinari L. 2004. Methods in human growth research. Cambridge University Press.

Hirsh, S. P., Pons, M., Joyal, S. V. and Swick, A. G. 2019. Avoiding holiday seasonal weight gain with nutrient-supported intermittent energy restriction: A pilot study. Journal of nutritional science. 8, e11-e11.

Hoffmann, T. C., Glasziou, P. P., Boutron, I., Milne, R., Perera, R., Moher, D., Altman, D. G., Barbour, V., Macdonald, H., Johnston, M., Lamb, S. E., Dixon-Woods, M., Mcculloch, P., Wyatt, J. C., Chan, A.-W. and Michie, S. 2014. Better reporting of interventions: Template for intervention description and replication (tidier) checklist and guide. The BMJ. 348, g1687.

Hutfless, S., Gudzune, K. A., Maruthur, N., Wilson, R. F., Bleich, S. N., Lau, B. D., Fawole, O. A., Anderson, C. a. M. and Segal, J. 2013. Strategies to prevent weight gain in adults: A systematic review. American Journal of Preventive Medicine. 45, e41-e51.

Kaviani, S., Vandellen, M. and Cooper, J. A. 2019. Daily selfweighing to prevent holiday-associated weight gain in adults. Obesity. 27, 908-916.

Lemmens, V. E. P. P., Oenema, A., Klepp, K. I., Henriksen, H. B. and Brug, J. 2008. A systematic review of the evidence regarding efficacy of obesity prevention interventions among adults. Obesity Reviews. 9, 446-455.

Liu, K., Liu, B. and Heilbronn, L. K. 2020. Intermittent fasting: What questions should we be asking? Physiology & Behavior. 218, 112827.

Lombard, C. B., Deeks, A. A. and Teede, H. J. 2009. A systematic review of interventions aimed at the prevention of weight gain in adults. Public Health Nutrition. 12, 2236-2246.

Mason, F., Farley, A., Pallan, M., Sitch, A., Easter, C. and Daley, A. J. 2018. Effectiveness of a brief behavioural intervention to prevent weight gain over the christmas holiday period: Randomised controlled trial. The BMJ. 363, k4867.

Norma Oficial Mexicana 2013. NOM-043-SSA2-2012, Servicios básicos de salud promoción y educación para la salud en materia alimentaria. Criterios para brindar orientación.

Orehek, E., Vazeou-Nieuwenhuis, A., Quick, E. and Weaverling, G. C. 2017. Attachment and self-regulation. Personality and Social Psychology Bulletin. 43, 365-380.

Organización Mundial de la Salud 2020. Brote de enfermedad por coronavirus (covid-19): Orientaciones para el público.

Whelton, P. K., Carey, R. M., Aronow, W. S., Casey, D. E., Collins, K. J., Dennison Himmelfarb, C., Depalma, S. M., Gidding, S., Jamerson, K. A., Jones, D. W., Maclaughlin, E. J., Muntner, P., Ovbiagele, B., Smith, S. C., Spencer, C. C., Stafford, R. S., Taler, S. J., Thomas, R. J., Williams, K. A., Williamson, J. D. and Wright, J. T. 2017. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/ APHA/ASH/ASPC/NMA/PCNA Guideline for the prevention, detection, evaluation, and management of high blood pressure in adults. Hypertension. 71, e13-e115.

Zúniga, M. A., Carrillo-Jiménez, G. T., Fos, P. J., Gandek, B. and Medina-Moreno, M. R. 1999. Evaluación del estado de salud con la encuesta sf-36: Resultados preliminares en méxico. Salud Pública de México. 41, 110-118.