To date, the prevalence of Hypertension (HPT) is getting increase worldwide. This situation is contributed mostly by the Lower-Income Countries (LIC) and Lower-Middle-Income Countries (LMICs) include Asians. Elevated Blood Pressure (EBP) in the early phase is often unrealized before developing to HPT, leading to several diseases in terms of cardiovascular diseases (CVDs). In preventing EBP, the European Society of Cardiology in 2017 classifies blood pressure into three groups; normal, pre-hypertension, and hypertensive crisis. People in the normal phase with the high-normal line are classified into EBP. If this group is determined and controlled, they will further keep in normal blood pressure. Contrarily, they are experiencing the next phase of HPT.

Like other Asian countries, Indonesia was experiencing an extreme prevalence of HPT, and Aceh, which is one of the provinces in Indonesia has a very high prevalence of HPT as well (20% increment from 2013-2018), is estimated to equal to the EBP prevalence. Despite many promotive and preventive interventions confirmed to decrease HPT, early screening has been convinced to recover the HPT in Indonesia. However, the HPT prevalence was examined steadily increasing. Intermittent fasting (IF) is recognized as a new method in decreasing metabolic factors based on several types of research currently. Therefore, the investigators are studying the effectiveness of intermittent fasting on people with EBP. Conducting healthy lifestyle intervention that is inexpensive, doable, and easily accessible, would be a new method for controlling EBP.

This trial aims to evaluate the effectiveness of three months intermittent fasting intervention followed by three months maintenance phase in stabilizing blood pressure among the EBP group with the high-normal signal. This trial will conducts in Aceh, Indonesia.

Trial procedure

1. In the beginning, the researcher chooses the allocation group for either intervention or control group based on the potential number of workers from each department. Based on that, it was decided that the intervention group is the Governor's office, and the Aceh Besar regency secretariat is the control group.
2. Letters of permission are submitted to both departments and continued by blood pressure screening once it is approved. Hence, the enumerators will screen all the workers. Each eligible participant (EBP 130-139/85-89 mm Hg and BMI ³ 25 kilograms/m2) will be invited to join blood pressure plus nutrition class on the day after, and fulfill the baseline characteristic questionnaire once they sign the informed consent. During the class, the researcher will describe the study procedure, study objective, process, monitoring, follow-up, methodology, risk and benefit, confidentiality, anonymity, and withdrawal from the study in both groups with the different context of intervention. Because of the covid-19 pandemic, all participants are allocated in a few small groups during baseline training.
3. The participants will join complete anthropometric measurements and fulfill questions in the STEP instrument and GPAQ instrument. Four enumerators will assist the participants; however, they will be blinded to intervention assignment.
4. The intervention group will undergo two fasting days and five ad libitum days during the intervention phase and continued to the maintenance phase. Otherwise, the control group will have a usual diet before the trial. Furthermore, both groups will have current exercise.
5. Calculation of the actual sample size to detect effect size in the primary and secondary objectives of the project has been conducted. Sample selection techniques will be described further in the published paper.
6. A mixed linear model will be applied to count the intervention effects (blood pressure, body weight, body mass index, waist circumference, and calorie intake), while a generalized estimating equation (GEE) will be used as well for categorical outcomes. Characteristics at baseline will be summarised by each arm using numbers and percentages, means and standard deviations or medians, and inter-quartile ranges where applicable.

Inclusion Criteria:

1. Adult between 18-60 years with EBP 130-139/85-89 mm Hg;
2. Overweight and obese with BMI above is equal to 25 kilogram/m2;
3. Do not have any gastric diseases or problems with the fasting;
4. Able to read and write;
5. Willing to sign the inform consent

Exclusion Criteria:

1. Disability person;
2. In medication either blood pressure or another disease;
3. Pregnant woman;
4. Employees who will be retired in the intervention duration;
5. Employees who will undergo hajj pilgrimage in the year 2021.