Kidney Diet Tips

Food Facts Friday: Watermelon

Summer is a season to find the small pleasures in life. One of those pleasures for me is having watermelon on the back deck in the warm sunshine. It’s a feeling of summer. Tasting the sweetness of the melon as the juices dribble down my arm brings back wonderful childhood memories.

Being a dietitian, I get many questions about watermelon and whether or not it is safe to include on a kidney diet. Watermelon is a good source of vitamin C, beta carotene and lycopene. It is very low in sodium and phosphorus. That sounds good, doesn’t it? So what are the concerns?  

There are three components of watermelon that are of particular interest for someone following a kidney diet: portion size, potassium and fluid.

Portion Size

The typical portion size of watermelon is a medium wedge which equals about 3 cups. For someone following a fluid and potassium restricted kidney diet, a wedge of watermelon contains too much fluid and potassium. Therefore, dietitians recommend a 1 cup serving. It may not sound like a lot, however cutting the fruit into bite size pieces or cutting the portion into small triangular shape pieces makes that 1 cup look like a whole lot more!

Potassium in Watermelon

Many fruits and vegetables contain potassium, therefore monitoring the number of daily portions and the portion size is essential for controlling potassium intake. Most melons are much higher in potassium than watermelon. For example, one cup of cantaloupe contains 425 mg potassium. One cup of watermelon contains only 180 mg potassium. That is why watermelon is usually the only melon included in a low-potassium kidney diet. Use the Food Analyzer to look up potassium content of other melons to compare.

Portion size is also important when it comes to potassium. A “normal size” wedge of a 10 pound watermelon (1/16th of a melon) contains 320 mg potassium. Being mindful of the 1 cup portion size that provides a reasonable amount of potassium means a person on a kidney diet can enjoy the sweet taste of summer!

Fluid in Watermelon

It’s easy to exceed your fluid goals, especially in the summertime! Watermelon is 92% liquid with 1 wedge of watermelon having close to 3 cup of fluid. For those following a fluid restriction, watermelon is limited to 1 cup for this reason.

Planning a portion of watermelon into your kidney diet is possible with awareness of the correct portion size to help keep potassium and fluid at an acceptable level. Check with your dietitian if you have questions about including watermelon in your diet.

Watermelon Recipes

Check out these kidney-friendly watermelon recipes:

Additional Kidney Diet Resources

Visit and explore these diet and nutrition resources:

This article is for informational purposes only and is not a substitute for medical advice or treatment. Consult your physician and dietitian regarding your specific diagnosis, treatment, diet and health questions.

Stephanie Suhai, MS, RD

Stephanie Suhai, MS, RD

Stephanie Suhai, MS, RD has been a dietitian for 10 years, working in acute care, sub-acute rehab, and long term care and now works in dialysis with both hemodialysis and peritoneal dialysis patients. She holds a passion for clinical nutrition research, counseling and education. In her free time she enjoys traveling, reading, staying active and spending time with her family.