Haemodialysis (HD) is the most commonly used method among renal replacement therapy options in patients with End Stage Renal Failure. Although one of the most important factors affecting the success of this treatment is compliance with fluid restriction, the rates of non-compliance with fluid control vary between 10-74%. It is understood from the literature that fluid restriction is one of the most difficult areas in compliance with HD treatment. Interdialytic weight gain is the most widely accepted method to assess compliance with fluid control by measuring the amount of fluid accumulated in the body. Thus, studies on this subject have shown that excessive interdialytic weight gain is a common problem in HD patients. It is known that excessive interdialytic weight gain increases the risk of morbidity and mortality in HD patients. The main factors causing interdialytic weight gain are fluid and salt intake between two HD sessions is appears to be. Therefore, it is stated that the easiest solution to control excessive interdialytic weight gain is to reduce fluid and salt intake. However, studies have reported that HD patients have difficulty in adapting to a salt-restricted diet, and in this case, they increase their fluid consumption. Therefore, it is of vital importance that public health nurses carry out interventions to ensure HD patients' compliance with fluid and salt control. In the literature review conducted with this perspective, studies were encountered in which results were obtained that m-health interventions provided a decrease in interdialytic weight gain averages and sodium intake. In this direction, a HafifMod programme based on the use of mobile health technologies was created. The aim of the study is to examine the effect of the LightMod programme for fluid and salt control guided by the Health Belief Model on interdialytic weight gain in routine haemodialysis patients.

Methods such as patient education and self-monitoring have been reported to be effective in ensuring compliance of haemodialysis patients with dietary and fluid restrictions. Methods accepted to be effective in ensuring compliance with fluid restriction include measuring the amount of fluid intake throughout the day, sharing the fluid to be taken during the day, and avoiding salty foods in patients' diets. It is stated that m-Health applications such as recording diet and fluid intake for monitoring and evaluation of nutrition are very useful for self-diet management of dialysis patients. At the same time, it is stated that the training approach based on the delivery of training modules created for the management of chronic diseases through mobile technological tools such as tablet computers has potential benefits.

It is thought that individual beliefs, values and attitudes have a significant impact on the health behaviors of routine HD patients to adapt to fluid and salt restriction.Therefore, interventions within the framework of the HafifMod programme, which will be prepared in line with the Health Belief Model, may be effective in developing positive beliefs, attitudes and behaviours towards fluid and salt control in routine HD patients.

The study is a quasi-randomised active controlled experimental study with single blind (participant) structure. The population of the study consisted of patients receiving routine haemodialysis treatment in the HD unit of Akdeniz University Hospital. According to the days of treatment, there are two separate groups receiving HD treatment 'Monday-Wednesday-Friday' or 'Tuesday-Thursday-Saturday'. As a result of the draw of lots, the groups were divided into two (intervention and active control) according to the days of treatment.Each group is planned to have an equal number of 17 participants. A quasi-randomised controlled study was designed in which sample selection would be made by random sampling method among the intervention and active control groups. This design was based on the principles of the TREND (Transparent Reporting of Evaluation with Nonrandomised Designs) guideline, which is recommended for the design and reporting of quasi-experimental studies.

HafifMod Programme consists of a modular training application and a mobile application offered to HD patients.The implementation period of the HafifMod programme consists of a 3-month period.Repeated measurements will be made for the intervention and active control groups, and a total of four tests will be performed at the 1st, 4th, 8th and 12th weeks.Modular training will be continued for a total of 5 weeks. Patient follow-up will be performed in the remaining weeks. Interdialytic weight gain and monthly serum sodium levels will be monitored at the beginning of each dialysis session. In addition, pre-test and post-test measurements will be performed using the Fluid Control in Haemodialysis Patients Scale and the Beliefs about Dietary Compliance Scale.

Inclusion Criteria:

• Those who gained more than 3% of their dry weight in at least one of the interdialytic weight gains covering the four-week period before the start of the study,
• Those who have received routine HD treatment for at least three months,
• Those whose dry weight has been determined,
• Smartphone users,
• Those who do not have severe visual and hearing impairment that would constitute an obstacle to the research,
• Those who are place, time and person oriented,
• Outpatients receiving HD treatment,
• Those with a routine HD program of 3 days and 4 hours a week,
• Those who do not have a psychiatric disorder that would constitute an obstacle to the research.

Exclusion Criteria:

• Those receiving home hemodialysis treatment,
• Those in the home hemodialysis training process,
• Those with plans to make changes to the dialysis center in the next three months from the start of the study,
• Patients who do not undergo ultrafiltration because their urine volume is sufficient.

It will not be shared for the purpose of confidentiality and protection of personal data.