Watermelon is very healthy with many antioxidants like lycopene and vitamin C. It is good in summer. Its anti-oxidants are important to neutralize the aggressive free radicals. It has more lycopene than tomato. It is important to prevent cancer.
The nutrients in 100 g edible watermelon include:

• Water – 90.3 g
• Protein – 0.6 g
• Fat – 0.2 g
• Carbohydrates – 8.3 g
• Salicylic acid 2.4 mg
• Fibre – 0.2 g
• Minerals - 0.4 g – sodium 1 mg, potassium 115 mg, magnesium 9 mg, calcium 7 mg, iron 225 micro g, copper 30 micro g, zinc 85 micro g, iodide 1 micro g
• Vitamins - vitamins A, B1, B6, nicotine amide, pantothenic acid, folic acid, vitamin C – 6 mg, vitamin K.

If you want to reduce your weight it is very good. It is a fruit for everybody.