Study will be done by consortium of pediatrician from Indonesia, Japan, and Germany. This team will act as leaders while the field assistant will consist of nutritionist and general practitioner. The chosen primary endpoint is the improvement of weight for age (grams) of the sample after one month of intervention. Participants are weight faltering babies aged 6-12 months at study entry, with the weight increments below P 15th of WHO weight increments tables whose parents agreed to be included in the study by providing written informed consent. The investigators aim to include 2 x 94 babies for a randomized control trial study residing in Makassar, South Sulawesi. They will be selected and enrolled after matching for age and sex. All babies will be examined in for their nutritional status, demographics, medical history, preexisting conditions, medication use, their dietary analysis (by 3-days food recalls), gut microbiota and fecal metabolome. The direct (face to face) monitoring sessions will be conducted at the enrollment, one month, two months and at the end of the study (at the third month) by giving routine clinical care to all enrolled babies, which included physical examination, growth monitoring, health, and nutrition education (counseling on infant and young child feeding practices, personal hygiene, and hand washing). This monitoring session will be held by practitioner and nutritionist. Subjects will be chosen based of the inclusion \& exclusion criteria. There are two research groups. The first group will be given pediatric nutrition care (PNC). In this group parents will receive nutritional advice about how many calories are needed, the type and form of food that can be given so that the baby can gain weight accordingly. In the second group, subject will receive PNC and food for special medically purposes/FSMP that will be given according to daily calorie needs which are determined based on ideal body weight (BB) according to body length. In general, FSMP will be given 3 times a day, according to the needs of each subject. Parents will be taught about preparation of FSMP e.g., dissolving and the correct amount of product (image will be attached in the appendix). FSMP will be given during the research period and will be discontinued when participant do not need it anymore.

Infants whose weight gain is below the 5th percentile of the WHO weight gain table and infants who are already mildly undernourished will be immediately given PNC + FSMP and not included in the PNC group. At the beginning of the study, parents will be asked about the type of food and milk consumed, amount and eating patterns, the incidence of illness such as fever, cough, runny nose, diarrhea, vomiting, sleep, and the general condition of the baby. Research team till measure body weight, length, head circumference and take the feces for microbiota and metabolome examination before intervention. Feces obtained will be stored at temperatures below 5ºC for a maximum of 24 hours. Subjects will be monitored for 4 weeks. In the fourth weeks there will be an examination of body weight, length, episodes of illness and stool collection for the second examination of microbiota and metabolome. At the end of the first month intervention, the investigators will ask the parents for giving permission to draw the blood from their children to see the plasma metabolome.

If within 4 weeks, the baby has gained a good weight gain according to the existing table (above P 15), then the subject does not need to take FSMP again but will continue to be monitored every month to prevent the second growth faltering event. If the baby is initially in the PNC group and does not gain good weight, PNC + FSMP will be given. The intervention and monitoring will be done for a total of 12 weeks. Every week, the total volume that had been consumed will be monitored by the field assistant by phone. Product acceptance questionnaires for the FSMP product will be assessed using a questionnaire during the monitoring visits at visit 1, 2 and 3. The occurrence of adverse events and medication use was recorded throughout the whole study period. All subjects will be provided with BPJS insurance during the study period up to one month after the study is completed.