The study examines how nutrient-rich muesli influences stress tolerance and reproductive traits in Drosophila melanogaster. Flies were cultured on wheat cream agar supplemented with 10 g, 20 g, and 30 g of muesli to evaluate their resistance to heat stress. Results indicated that flies fed with 20 g and 30 g muesli showed higher heat resistance compared to those given 10 g muesli, while control flies had the lowest tolerance. Female flies generally exhibited greater heat resistance than males across all diet conditions. Among females, mated individuals performed better than unmated ones, whereas mated males showed slightly improved resistance compared to unmated males. Overall, the findings suggest that increasing muesli concentration enhances heat resistance in Drosophila melanogaster.