Kalingda (Citrullus colocynthis), locally known as Mateera or Kalingda in the Indian arid zones, is a drought-hardy, underutilized cucurbit with immense nutritional, medicinal, and ecological value. Traditionally cultivated in harsh desert climates with minimal inputs, this ancient crop offers a rich source of edible seeds known for their high oil and protein content. The fruit rind also serves as nutritious livestock fodder, aiding in sustainable resource use. As modern diets narrow and climate-resilient food sources gain global attention, Kalingda emerges as a vital fasting superfood—nutrient-dense, culturally significant, and ideal for low-calorie, high-impact dietary regimens. Its bioactive compounds, adaptogenic potential, and heritage use in dryland mixed farming systems align it with the emerging paradigm of food security, resilience, and health during fasting periods. This chapter explores the botany, nutritional profile, traditional uses, and modern research advances on Kalingda, making a compelling case for its inclusion in the global repertoire of sustainable superfoods.