Picture this: It’s a beautiful fall day, and you and a friend just finished a nice three-mile run. You’re about to sink your teeth into a juicy, sweet slice of watermelon…when your friend mentioned she heard watermelon might make you gain weight. You immediately pause and wonder – is this true? Is watermelon fattening?
Let’s find out…
Disclosure: This post is sponsored by the National Watermelon Promotion Board. As always, all opinions are my own.
So is watermelon fattening?…
Let me give you the very quick answer – heck no!
I’ll explain all the science in more detail below, but that’s the short and sweet version.
We’re bombarded with messages about nutrition these days, often from sources that are not actually experts in nutrition. Well-meaning folks see that watermelon has sugar an immediately assume it’s not a good choice. What they fail to do is take into account all the other beneficial components of watermelon (and fruit in general) – and actually dig into the research on this.
1. Fruit, Sugar, and Weight
To start, let’s consider the big picture topic of fruit, sugar, and weight.
Sugar is often villainized in the media as the cause of many health problems. While I completely agree that we need to limit added sugar in the diet, natural sugar in fruit comes packaged with many beneficial components. Depending on the fruit, this can include vitamins, minerals, fiber, phytochemicals, antioxidants, and more.
As an RD, I firmly believe in the benefits of eating whole fruits (and that they outweigh any sugar concerns).
But of course, that’s just my opinion. What does the research say?
- A 2017 review article found that eating whole fruit was actually associated with a reduced risk of long-term weight gain among middle aged adults. They postulated that eating whole fruits may be linked to a lower overall energy intake (perhaps due to satiety from the fruit).
- A 2009 study examined the effects of fruit intake on a subsequent meal. Eating an apple 15 minutes prior to a meal led to a lower overall energy intake (including both the apple and the meal) compared to the control group eating just the meal.
- A 2019 study found that fruit and vegetable intake helped mitigate genetic predispositions to long-term weight gain.
- Another 2019 study looked at Korean adults, and found that eating whole fruit at least one time/day was associated with reduced prevalence of obesity and high blood pressure compared with eating fruit less than one time per week.
- And lastly, another 2019 review article came to this conclusion: “Whole, fresh fruit probably does not contribute to obesity and may have a place in the prevention and management of excess adiposity.” (Side note: adiposity = fat tissue). They noted that this was supported by both single bout randomized control trials, trials that have lasted 3-24 weeks, as well as long term observational trials.
Hopefully this makes it clear that a large body of research out there does not connect fruit to weight gain; on the contrary it indicates that whole fruit may actually have some protective effects.
2. Glycemic Index, Watermelon, and Weight
But what about watermelon itself? Is watermelon fattening even if fruit as a category isn’t – maybe because of glycemic index concerns?
Nope! Watermelon is not fattening, just like other fruits are not fattening.
One of the reasons watermelon has been called out in the past is due to it’s glycemic index. Glycemic index (GI) is a measure of the relative rise in blood sugar from a certain type of food – or in other words, how quickly that food will break down into sugar in the blood. Some professionals postulate that a high GI diet may lead to weight gain.
Watermelon has a glycemic index of 72 (out of 100), which is considered high. That sounds bad, right?
Here’s the thing – a normal portion size of watermelon does not actually contain massive amounts of carbohydrate. So the glycemic load (GL) – the measurement that takes into account standard portion sizes of carb-rich foods and their effect on blood sugar – is actually relatively low.
Not only is the glycemic load for watermelon low, but there’s also been new research questioning whether GI or GL even matters for body weight among healthy adults.
For example, one study notes “Cross-sectional data are inconsistent both in the direction and strength of association between GI or GL and body weight, and this being the case, do not support a strong role of dietary GI or GL on body weight.”
Now that doesn’t mean we should ignore blood sugar impacts of food. But there’s probably far more that goes into overall diet quality and its relation to weight than solely looking at glycemic impact. And even within that space, it’s better to look at glycemic load which takes into account the standard serving of a food.
When we do that, it’s clear we don’t have to worry about watermelon.
3. Watermelon & Weight Research
Now there hasn’t been much research looking at only watermelon (as opposed to fruit in general) and weight gain/loss. It’s a super niche topic. But there’s one very interesting study released in early 2019 that I think will help ease your mind.
This study looked specifically at watermelon and several health-related measures. They gathered up a group of overweight and obese men and women, and divided them into two groups – one group snacked on 2 cups of watermelon, and the other snacked on vanilla wafer cookies.
The people participating in the study could eat their snack at any time of the day, and it could be alone or with other foods – the only instruction was they were supposed to eat it daily.
After 4 weeks of this, the groups took a short break (a “washout period” of 2-4 weeks) then returned to complete 4 weeks eating the other snack that they didn’t originally have.
Both snacks had 92 calories each. Carbohydrates were relatively similar between the watermelon and cookies at 23 grams (1 g fiber) and 18 grams (0 g fiber), respectively. Watermelon was higher in sugar compared to the cookies (17 g vs 9 g).
Ready for the results? These are pretty cool:
After four weeks of the watermelon intervention, body weight and BMI were significantly lower – but after four weeks of cookies, they were significantly higher. Four weeks of cookies led to higher blood pressure and body fat as well (no change in the watermelon intervention).
The study also showed that the watermelon led to longer periods of feeling full and satisfied after eating the snack.
So even though the calories in the snack were the same, and the watermelon actually had more sugar – it led to greater immediate satiety ratings, as well as weight loss after the month-long intervention.
Pass me that watermelon, will ya?!
4. Watermelon, Weight & Overall Health
At this point, hopefully you’re confident in the fact that eating fruit – including watermelon – will not make you fat. In reality, it’s a nutritious part of a balanced diet!
Here are a few benefits to eating watermelon:
- Watermelon is 92% water, which supports hydration for your body. Some research – like this study and this one – suggest that water intake may actually be linked to lower body weight or weight loss. It’s plausible that high-fluid foods like watermelon may play a role in this too (but not conclusive of course).
- It’s a lycopene leader, packing in more of this powerful antioxidant than other fresh fruits or vegetables. Lycopene may play a role in cancer prevention and protecting the body from the sun’s UV rays.
- Watermelon is also a good source of Vitamin C, helping maintain immune health, as well as Vitamin A, which is key for eyesight.
5. How to Include Watermelon in Your Diet
If you’re ready to stock up on watermelon now, consider these fun and delicious ways to add it to your diet:
- Put together this stunning watermelon and chocolate dessert board for your next holiday party! It’s gorgeous, delicious, and nutritious.
- Freeze watermelon now so you can add chunks to smoothies in the wintertime! You might love my watermelon cucumber smoothie for a refreshing and hydrating drink.
- Try this watermelon rind bruschetta for a unique appetizer for your upcoming holiday parties!
- Are you working out a lot? Try my watermelon homemade sports drink for a simple, natural way to fuel yourself.
- Make these sour watermelon lime protein gummies for a healthy homemade candy – great for you or the kids!
I hope this article helped you understand why watermelon is not fattening, and encourages you to add some of this juicy, sweet treat to your meals! For more recipe ideas, be sure to visit the Watermelon Board website.
Share: Did this help clear up the age-old question about watermelon being fattening? What’s your favorite way to enjoy watermelon?
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Well, I was never worried about watermelon being fattening LOL It is such a great fruit, but I don’t think to eat much of it in the winter…. it’s probably still available in the stores, but I never think to even look for it. Thanks for all this great info!
Sure thing! I’m glad you were never worried LOL – some people do really get concerned about it!
I know our store carries watermelon year round – not always the big ones but we always have the minis. Might be good to keep an eye out for!
I was never under the impression that watermelon wat fattening. I like watermelon in the summer when it’s super hot out!
Me too – nothing better on a hot day than a juicy slice!!
Watermelon is one of the best parts of summer! I believe all fruits are good for you
Yessss! Totally agree with you my friend!
I adore watermelon and never would have considered it to be fattening. This is super helpful info.
I’m so glad most of you reading this never fell into this trap! You’d be surprised how often I hear it!
I think this kind of misinformation comes from people wanting to emulate someone else’s diet regimen because they think it’ll magically transform them. Tom Brady & Giselle Bundchen do not eat fruit because of its sugar content; they are in fantastic physical condition because of their fitness regimen (and good genes), not because they don’t eat fruit.
I think the best example of why it’s a bad idea to assume a famous athlete’s diet will work for you is that of high-profile Kenyan runners. Their diet is almost entirely carbohydrate based (mid-80%), but what’s shocking is that 20% of their calories come from the sugar they put in their tea. No one should assume they could magically transform their athleticism by consuming lots of plain white sugar. It works for the Kenyan runners because their diets are otherwise very healthy & because they’re already elite athletes.
I’m fat and I have hypertension & a strong family history of Type 2 diabetes. I give myself free rein to eat simple carbs during workouts (hello bagels!), but I know it’s in my best interest to avoid processed simple carbohydrate as much as is practicable. Pity, too: I would love nothing better than to dump a tablespoon of honey in every cup of tea I drink.
Oh man, you are SO right. Don’t get me started on Tom and Giselle, LOL.
So interesting about the sugar in tea for Kenyan runners – I didn’t know that!
And I feel ya on the honey – my neighbor has a farm and they do their own honey; I’ve got a couple bottles from her and it’s just SO good. I have to stop myself from just eating it by the spoonful!
i think i was slightly concerned because ive been having the most outlandish watermelon in Greece and every day too…and I’ve been feeling kind of bigger than usual…maybe its the heat (outlandish too) and maybe its the superhydration of this amazing fruit..these specific open air market producers must receive an award or a gold medal for the absolute bestest WATERMELON production….never had anything like them….. .if you’ve never been to Greece, if you’ve only had fruit of NONGREEK origin ..you’ve NEVER had genuine juicy saliva drooling fruit -NO JOKE.
Well I feel like I need a trip to Greece now! 😉
The reason I ask is because I eat a lot of watermelon and for some reason, I’m picking up pounds, not inches but pounds and I was just curious if the watermelon is the cause of this because that’s the only thing that I have added to my diet.
Hi there! There’s no evidence to suggest that watermelon causes weight gain compared to any other food in someone’s diet. If someone was eating more calories than their body needs, it could cause weight gain regardless of the source of those calories. 🙂 Watermelon is fairly low in calories, though, so it could be portion sizes of other foods in the diet – or, on the flip side, if someone was strength training regularly, the scale can shift with building muscle mass. If you’re concerned about your diet, I highly recommend seeing a dietitian that can help you by fully assessing your diet and providing personalized advice.
You need to consider the type of sugar … watermelon is high in fructose – and you can do a search on this, but fructose can only be broken down by the liver. People don’t realize that fructose is a big culprit in the massive fatty liver epidemic that we have in this country. I’m not saying, watermelon is anywhere near being the chief cause of us but it’s something to consider if some of you are gaining weight. As much as I personally love, watermelon, I try not to eat a lot of it and try to pick fruits that are lower in fructose such as cantaloupes.
Hi there! Thanks so much for sharing your thoughts. You bring up a good point, and as an RD, hopefully I can provide some context here. You are definitely correct that excess fructose consumption, particularly from added sugars, is linked to fatty liver. However, 2 cups of watermelon, which is a standard portion size, only contains 10 grams of fructose, and comes packaged with vitamins, minerals, and phytochemicals. You can compare this to a 12-oz can of soda which has 22 grams of fructose and no positive nutrition attributes. Most research out there on MAFLD (formerly known as NAFLD, non alcoholic fatty liver disease) links a consumption of excess added fructose, namely sugar-sweetened beverages, with the condition. For example, Assy et al. (2008) found that 80% of those with fatty liver consumed excessive sugar sweetened beverages (more than 50 grams per day of added sugar) compared to 20% of control subjects. Abid et al. (2009) reached similar conclusions. There was also a great systematic review and meta analysis in Nutrients (Lee et al, 2022), which concluded: “The evidence supports reducing the consumption of SSBs as a source of excess energy, while it does not support avoidance of food sources such as 100% fruit juice, dried fruit, mixed fruit, or plant-based dairy alternative”. Some observational studies have found inverse associations between fruit consumption and MAFLD (granted, they have not teased out individual fruits, and some studies have suggested more than 4 servings of fruit per day may exacerbate issues in those who already have FLD). And newer animal research suggests a specific amino acid in watermelon, L-citrulline, may have a role in inhibiting liver fat accumulation (Kudo et al, 2021). My opinion (as a dietitian looking at the current body of research) is that it is extremely unlikely anyone is over-consuming enough watermelon regularly to be problematic, but rather the common over-consumption of sweetened beverages and baked goods is far more problematic in the context of developing MAFLD. 🙂
Hey Chrissy,
Thanks for that reply ! You are spot on with all the above info. Also, your site is awesome! I can tell you put a lot of your heart into it. It’s a wonderful resource for all of us health conscious folks out there. Many thanks to you !
You’re very welcome! I appreciate you taking the time to leave the kind words 🙂