Abstract: Background and Objective: The prevalence of under nutrition is relatively higher than malnutrition. Under nutrition is a combination between inadequate nutrition intakes and infectious diseases. Problems of under nutrition could overcome through the provision of a proper diet to increase weight. WHO has recommended F-100 formula as complementary feeding for a quick weight gain in toddlers suffering from acute malnutrition. The aim of this study was to know the influence of consumption F-100 that be applied by adding carbohydrate food from local ingredient modifications as complementary feeding for underweight toddlers. Materials and Methods: This research adopt quasi experimental pre-post test with control group design. It was conducted in 3 districts in South Tangerang Regency, Banten, Indonesia. They were divided into 2 groups having 40 toddlers as a treatment/experimental group and 33 toddlers as a control group. Data processing and data analysis were carried out using paired t-test and changes in treatment and control groups were tested using t-test independent. Results: The results showed that they were different with weight changes (p = 0.00), height changes (p = 0.00) and Z-score index W/A (p = 0.15), W/H (p = 0.01) and H/A (p =0.02) between the treatment group and the control group. Conclusion: F-100 (liquid) or modified F-100 with locally made flour used as a complementary feeding for solving the acute malnutrition in children.