The feasibility study was conducted using a mixed-methods single group, pre and post-test design (Quasi experiment) approach. The investigator assessed if a weight reduction program using WhatsApp and peer support would work well enough to conduct a larger study. The investigator conducted the study in an urban slum (Azam Basti) in Karachi, Pakistan and enrolled 50 participants, along with participant nominated peers from the same family. Initial eligibility was assessed over the phone. Those who met the initial eligibility were visited to assess eligibility in terms of BMI (23 kg/m2 and above). Height was measured in centimeters (cm) and weight in kilograms (kgs) using a digital weighing scale. Both values were entered into the web-based calculator to calculate BMI. Participants with a BMI of 23 kg/m2 and above were enrolled and written informed consent was obtained. The participants then nominated one peer from the family. Peer eligibility was assessed and written informed consent was obtained. Once the participants and peers were enrolled in the study, the baseline assessments were completed. During the baseline assessments, participants were interviewed for sociodemographic and health-related information, 24-hour dietary recall, and Global Physical Activity Questionnaire (GPAQ). Peers were also interviewed for sociodemographic information. After the baseline assessment, the participants and peers received lifestyle modification education through WhatsApp voice calls for three days and then once monthly for one year delivered by a trained nutritionist. The intervention was delivered mostly in groups. The peer-supported lifestyle modification intervention was developed with the aim of helping participants adopt healthier lifestyles by making dietary changes, increasing physical activity, and achieving a weight loss goal of 5% of their initial body weight. Additionally, the intervention aimed to prevent weight gain among participants. The participants were followed-up for one year. Participants weight (kg), diet through 24-hour dietary recall, and physical activity through Global Physical Activity Questionnaire (GPAQ) were assessed every month. Social support questionnaire was also asked from participants at 3, 6, 9, and 12 months. The investigator also conducted in-depth interviews at the end of the study with study participants and peers to understand the barriers, facilitators, and experiences of the lifestyle modification intervention program.

Inclusion Criteria for Participants:

• Males and females
• Aged 20 to 60 years
• Had access to smartphones and an internet connection
• Agreed to nominate one peer from their family
• Provide written informed consent

Exclusion Criteria for Participants:

• Pregnancy
• Chronic conditions, disability, and other health-related issues that require special treatment and dietary and physical activity restrictions

Eligibility Criteria for Peers:

• Males and females
• Aged 20 years and above
• Willing to attend online training sessions
• Agreed to help participants with lifestyle modification adherence throughout the study
• Provide written informed consent