Is watermelon good for weight loss?

Not on its own. A 2023 meta-analysis of 9 randomized trials found that watermelon made no significant difference to BMI or body fat, and its abstract gives no size for that result. We found no randomized trial with weight loss as its main goal. The one study that tested whole watermelon as a snack in 33 adults with overweight saw weight fall, and it gave everyone watermelon first instead of randomizing the order.

Unsettled. Whether watermelon helps depends on what it replaces, and that has been tested once, weakly. In the 33 adults, two cups of fresh watermelon a day for four weeks lowered body weight and BMI, while the same calories from low-fat cookies for four weeks raised them. Because every participant had watermelon first and cookies second, the change cannot be separated from the passing of time. The size of the change in kilograms sits in a table we could not extract.

What the trials found

Watermelon trials pooled

The 2023 meta-analysis pooled randomized trials of watermelon published up to March 2022. It found lower systolic blood pressure and LDL cholesterol after watermelon, and no significant difference in BMI or body fat. The abstract gives no size for the BMI result. A 2025 dose-response meta-analysis of 21 randomized trials of L-citrulline, the amino acid watermelon is known for, found no overall effect on body weight, BMI, fat mass, waist size or body fat percentage. That was a supplement, and it closes off the idea that the amino acid does something special for weight.

The snack study

The 33 adults had a BMI of 25 to 40. Beyond the weight result, a single watermelon snack kept hunger lower than an equal-calorie cookie snack at 20, 40, 60 and 90 minutes, on self-rated scales. Being fuller after a snack is a reasonable route to eating less, and the study did not measure what people ate for the rest of the day.

Two trials that point the other way

In a randomized trial of overweight and obese postmenopausal women, six weeks of daily 100 percent watermelon puree lowered a blood marker linked to atherosclerosis by 6 percent, an effect the authors describe as independent of changes in body composition. In 128 women sent home after hospital care for severe pregnancy sickness, adding watermelon to dietary advice led to a median weight gain of 0.55 lb (0.25 kg) at two weeks against a 1.1 lb (0.5 kg) loss with advice alone. There, gaining weight was the aim. Watermelon added to a diet adds food, and it is the swap that might matter.

What is in it

USDA analysis of 8 samples of raw seedless watermelon found about 3.2 oz (91 g) of water and 7.2 g of sugars per 3.5 oz (100 g), with 3.2 g fructose, 1.5 g glucose and 2.5 g sucrose. Mostly water is why it fills a bowl with few calories. The sugars are ordinary fruit sugars.

Who should be careful

Not for everyone. If you have diabetes, watch your portions. The same 2023 meta-analysis of 9 randomized trials found watermelon significantly raised fasting blood sugar. The abstract gives no size for the rise, and the authors call for caution because the trials are few. In 10 healthy volunteers watermelon had a glycemic index of 55, classed as low, measured on a portion carrying 50 g of carbohydrate.

Watermelon has been behind food poisoning. In a 2009 outbreak in New Zealand, 15 cases were seven times more likely than 40 controls to have eaten watermelon, traced to one grower. Among 163 children aged 4 to 17 with allergies seen at a clinic in Sydney, watermelon was the fruit most often behind pollen-food syndrome, an itchy mouth after raw fruit. That was a clinic sample of allergic children, and it does not describe children in general. We found no study of watermelon with medicines, or in pregnancy beyond the pregnancy sickness trial above.

What expert bodies say

We found no statement from the CDC, the NIH or the European Food Safety Authority specific to watermelon and weight. Our search turned up consumer and industry pages, which are not sources.

More on the fruit itself is on the watermelon page.

How we searched

What would change this answer

• A randomized trial of whole watermelon against an equal-calorie snack in adults with overweight, either in parallel groups or with the order properly randomized, measuring weight over at least 12 weeks. None was registered on ClinicalTrials.gov on 7 October 2026.
• The size of the weight change in the existing snack study, which would show whether the effect is worth having even if it holds up.
• A measure of how big the rise in fasting blood sugar was in the pooled trials, which matters more for people with diabetes than for anyone counting calories.

Sources

1. ev-wmwl-01 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 9 RCTs
   However, there was not any significant difference in other outcomes of interest including diastolic blood pressure (DBP), heart rate (HR), BMI, body fat, and serum levels of arginine, insulin, and CRP after watermelon supplementation.
   
   Who: randomized controlled trials of watermelon supplementation, search to March 2022
   Effect: no significant difference in BMI or body fat; SBP, TC and LDL decreased
   Certainty: Abstract without effect sizes for BMI; most RCTs used juice or extract, not whole watermelon, and weight was not the primary aim.
   Diabetes Res Clin Pract, 2023 · checked 2026-10-07 · we read the abstract
2. ev-wmwl-02 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of RCTs · n = 21 RCTs
   Overall, CIT supplementation had no substantial effects on body mass index (BMI), body weight, fat mass (FM), waist circumference (WC), body fat percentage (BFP), and fat-free mass (FFM).
   
   Who: RCTs of L-citrulline supplementation published until March 2025
   Effect: no substantial effect on BMI, body weight, fat mass, waist circumference, body fat percentage, fat-free mass
   Certainty: Citrulline supplement, not watermelon; subgroups (>40 years, >6 g/day) are exploratory.
   Nutrients, 2025 · checked 2026-10-07 · we read the abstract
3. ev-wmwl-03 · Observational data · non-randomized crossover controlled trial (fixed order) · n = 33
   Body weight and BMI values did not differ significantly between the two interventions at baseline, but were significantly lower after four weeks of WM consumption and significantly higher after four weeks of LFC consumption compared with baseline values (Table 1).
   
   Who: overweight or obese adults (BMI 25-40), 2 cups fresh diced watermelon (92 calories) vs isocaloric low-fat cookies daily, 4 weeks each
   Effect: body weight and BMI significantly lower after watermelon and higher after cookies vs baseline; interaction p = 0.005 for body weight
   Certainty: Fixed order (watermelon first), not randomized; the size of the change in kg is only in Table 1, which could not be extracted; there is no funding section in the extracted text.
   Nutrients, 2019 · checked 2026-10-07 · we read the fulltext
4. ev-wmwl-04 · Observational data · non-randomized crossover controlled trial (fixed order) · n = 33
   Feelings of hunger were significantly greater for LFC compared with WM at 20, 40, 60, and 90 min (p < 0.05) (Figure 1a).
   
   Who: overweight or obese adults, single 92 calories snack of watermelon or low-fat cookies with 8 fl oz water
   Effect: hunger significantly greater after cookies at 20, 40, 60 and 90 min (p < 0.05)
   Certainty: Subjective VAS scales; no randomization of order.
   Nutrients, 2019 · checked 2026-10-07 · we read the fulltext
5. ev-wmwl-05 · Observational data · non-randomized crossover controlled trial (fixed order) · n = 33
   Eligible participants (n = 33) were assigned to a 4-week repeated measures crossover with two treatments given—a WM snack followed by a 2–4 week washout period, and then crossed over to an isocaloric-matched LFC snack.
   
   Who: overweight or obese adults
   Effect: fixed treatment order: watermelon, washout 2-4 weeks, then cookies
   Certainty: A methodological limitation, which is why the level is C, not B.
   Nutrients, 2019 · checked 2026-10-07 · we read the fulltext
6. ev-wmwl-06 · Randomized controlled trial(s) · randomized controlled trial · n = not stated in abstract
   We conclude that 6 weeks of watermelon supplementation improved soluble vascular cell adhesion molecule-1 levels, a marker connected to atherogenesis, independent of changes in body composition or glycemic control.
   
   Who: overweight and obese postmenopausal women, 100% watermelon puree daily vs no intervention, 6 weeks
   Effect: sVCAM-1 -6% (P = .003) within watermelon group; no change in body composition or glycemic control
   Certainty: The abstract does not give weight as a separate outcome; "independent of changes in body composition" is the authors' wording.
   Nutr Res, 2020 · checked 2026-10-07 · we read the abstract
7. ev-wmwl-07 · Randomized controlled trial(s) · randomized controlled trial · n = 128
   Weight change (kg) at end of week 1, median[interquartile range] -0.05[-0.775 to + 0.50] vs. -0.5[-1.4 to + 0.1] P = 0.014 and to the end of week 2, + 0.25[-0.65 to + 0.975] vs. -0.5[-1.3 to + 0.2] P = 0.001 for watermelon and control arms respectively.
   
   Who: women discharged after hospitalization for hyperemesis gravidarum, watermelon plus advice leaflet vs leaflet alone
   Effect: weight change week 2: median +0.55 lb (0.25 kg) vs -1.1 lb (-0.5 kg), P = 0.001
   Certainty: Here weight gain is the desired result; shows that watermelon by itself does not lower weight, the effect depends on what it replaces.
   BMC Pregnancy Childbirth, 2023 · checked 2026-10-07 · we read the abstract
8. ev-wmwl-08 · Position of an expert body · dataset · n = 8
   Watermelon, seedless, flesh only, raw | Water 90.91 g per 100 g (range 89.55-93.1, n=8) | Sugars, Total 7.197 g (5.11-8.44, n=8) | Fructose 3.246 g (2.34-3.98, n=8) | Glucose 1.474 g (0.65-2.3, n=8) | Sucrose 2.477 g (1.28-5.05, n=8)
   
   Who: US retail samples of seedless watermelon, flesh only, raw
   Effect: water 90.91 g/100 g (range 89.55-93.1); total sugars 7.197 g/100 g (5.11-8.44); fructose 3.246 g (2.34-3.98); glucose 1.474 g (0.65-2.3); sucrose 2.477 g (1.28-5.05)
   Certainty: There is no energy for the flesh in the dataset; low energy density follows from water. Excess fructose is important for people with fructose malabsorption (not from the dataset).
   USDA FoodData Central, Foundation Foods (release 2026-04-30), FDC 2747675, Watermelon, seedless, flesh only, raw · checked 2026-10-07 · we read the dataset
9. ev-wmwl-09 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 9 RCTs
   In addition, watermelon consumption led to a significant increase in fasting blood sugar (FBS).
   
   Who: randomized controlled trials of watermelon supplementation, search to March 2022
   Effect: significant increase in fasting blood sugar; size not given in abstract
   Certainty: Effect size not given in the abstract; the authors advise caution because of few studies. Significant for people with diabetes.
   Diabetes Res Clin Pract, 2023 · checked 2026-10-07 · we read the abstract
10. ev-wmwl-10 · Randomized controlled trial(s) · randomized crossover glycemic index test · n = 10
    Similarly, the glycemic index of pineapple, 82+/-4, was significantly greater than those of papaya, 58+/-6, watermelon, 55+/-3, and durian, 49+/-5 (p<0.05).
    
    Who: 10 healthy volunteers, 50 g available carbohydrate portions of glucose and test fruits in random order
    Effect: GI watermelon 55 +/- 3; pineapple 82 +/- 4; papaya 58; durian 49
    Certainty: Malaysian varieties; 50 g of available carbohydrate is about 700 g of watermelon, so the glycemic load of a normal serving is lower.
    Asia Pac J Clin Nutr, 2008 · checked 2026-10-07 · we read the abstract
11. ev-wmwl-11 · Observational data · outbreak case-control study · n = 55
    RESULTS: The case control study included 15 cases and 40 controls and found that cases were seven times more likely to have eaten watermelon compared with controls (p=0.026).
    
    Who: 15 cases of Salmonella Typhimurium phage type 1 and 40 controls, Gisborne region
    Effect: cases 7 times more likely to have eaten watermelon (p = 0.026); controlled by chlorine washing at pack house
    Certainty: A single outbreak; the risk comes from the rind surface, which is transferred to the flesh on cutting.
    N Z Med J, 2010 · checked 2026-10-07 · we read the abstract
12. ev-wmwl-12 · Observational data · cross-sectional study · n = 163
    All PFS-implicated fruits were tropical fruits with watermelon the most common.
    
    Who: atopic patients aged 4-17 years, pediatric allergy clinic, south-west Sydney
    Effect: PFS prevalence 4.9%; watermelon most common PFS fruit
    Certainty: Clinical sample of atopic children, not the general population.
    J Paediatr Child Health, 2014 · checked 2026-10-07 · we read the abstract