Watermelon is a source of a compound called citrulline. In a study published in Nutrition and Metabolic Insights, adding watermelon to the diet reduced inflammation in the body and led to weight loss and body fat. A review article published in Clinical and Experimental Pharmacological Physiology found that watermelon consumption may help lower blood sugar. Pumpkin leaves, muskmelon, cucumbers, and gourds are also sources of citrulline.