Abstract Background Infant and young child nutrition is fundamental to individual health and national economic growth. Malnutrition remains a major challenge, particularly in developing countries such as Tanzania. Despite being food-producing regions, Njombe and Iringa continue to experience high rates of undernutrition among children under five, largely due to knowledge gaps and poor feeding practices among caregivers. Aim To co-design age-specific meal plans using locally available foods in Njombe and Iringa, Tanzania. Research seeks to develop culturally, and economically feasible meal plans to improve child nutrition in Tanzania. Methods A five-step Human centered design approach will be employed: (1) Exploration through focus group discussions and key informant interviews to understand caregivers feeding challenges; (2) Co-design to develop meal plans incorporating affordable, locally available; (3) Validation and Refinement through focus group discussion and stakeholder feedback; (4) Implementation with trained Community Health Workers supporting caregivers in the adoption of meal plan; and (5) Evaluation using qualitative and quantitative methods to assess effectiveness and adoption over a one-year period. A total of 208 participants will be purposefully selected. Thematic analysis will be conducted using NVivo 12 software to identify key challenges caregivers face, facilitators, and locally available and affordable foods to be used in co-design of meal plan. Expected results The findings will provide insights about feeding challenges caregivers of under five children faces, meal plan prototypes tested and scaled up if proven successful. Successful implementation of these age specific meal plans, this study anticipates improved caregiver knowledge and practices regarding infant and young child feeding, increased dietary diversity, and enhanced nutritional outcomes among children under five children in Tanzania.

The authors have declared no competing interest.

The author(s) received no specific funding for this work.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Approval reference number include: Ref: AKU/2025/13/fb/02/163 This approval was given by the Aga Khan University Tanzania Ethical Review Committee. Contact is given below. Salama House, 344 Urambo Street, P.O. Box 125, Dar es Salaam, Tanzania Tel: +255 22 215 2293, 22 215 0051, Fax: +255 22 215 0875 Email: iedea@aku.edu www.aku.edu

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In request, the data can be requested through my email: aminieli.usiri@aku.edu