Diarrhoea and other digestive problems: An excellent source of water, watermelon is an equally great source of dietary fibre. However, eating large quantities may cause digestive problems like diarrhoea, bloating, flatulence, gas, etc. This fruit contains sorbitol, a sugar compound, which is known to encourage watery stools and gastrict problems. Also the lycopene content, which is a pigmented antioxidant that gives the watermelon its bright colour is known to create such health issues.