Watermelon and Citrulline Supplements for Body Composition
What it found
In 21 randomised trials in people, citrulline supplements, including watermelon juice, made no clear difference to body weight, BMI, fat mass, waist size, body fat percentage or fat-free mass overall.
Some small groups did show changes, but the authors rate the evidence for fat and fat-free mass as low.
What they found
Studies in people
Body weight and BMI
Across the trials, citrulline supplementation made no clear difference to body weight or BMI compared with placebo. Subgroups by dose, duration, sex, age, training type and baseline BMI all showed the same pattern.
Fat mass
Overall, there was no clear effect on fat mass. In subgroup analyses, fat mass went down in people over 40 years old and in those taking more than 6 g per day, but the authors say these exploratory findings need caution.
Fat-free mass
Overall, there was no clear effect on fat-free mass. In studies lasting 8 weeks or less, fat-free mass went up, but the authors note this may partly reflect water shifts rather than true muscle growth.
Waist and body fat percentage
Citrulline supplementation made no clear difference to waist circumference or body fat percentage compared with placebo.
Timing and dose patterns
The authors found a non-linear link between how long citrulline was taken and changes in fat mass and fat-free mass. This suggests effects may depend on how long someone takes it, not just the dose.
Other findings
Evidence quality
The authors rated the certainty of the evidence as high for BMI, moderate for body weight, body fat percentage and waist, and low for fat mass and fat-free mass. Seven of the 21 trials were judged to have a high risk of bias.
What the authors conclude
“The present meta-analysis demonstrated that CIT supplementation does not significantly influence body composition parameters in untrained or recreationally active individuals.”
Also in their conclusions
- They conclude that citrulline supplementation does not significantly influence body composition in untrained or recreationally active individuals.
- They say that although citrulline has been shown to improve some aspects of exercise performance, the evidence for meaningful fat loss or lean mass gain remains limited and inconclusive.
- They advise that future trials should control for diet and use standardised training protocols to better assess the long-term impact of citrulline on body composition.
How it was done
Citrulline is an amino acid found in watermelon and used as a supplement to boost exercise performance. The authors wanted to see whether those performance benefits actually translate into changes in body composition.
They pooled 21 randomised controlled trials published between 2015 and 2023, with 16 to 81 participants each, lasting 3 to 12 weeks. Participants included people with obesity, type 2 diabetes, high blood pressure, fatty liver disease, older adults, and trained athletes. Doses ranged from 0.5 to 10 g per day of citrulline or watermelon juice.
What it can’t tell you
- Most included trials did not control for what people ate or how they trained, so the results may mix the effects of citrulline with those other factors.
- The trials were short, lasting 3 to 12 weeks, so this paper cannot show what happens over the long term.
- Some trials used watermelon juice, which contains other compounds besides citrulline, so the exact effect of citrulline alone is unclear.
Who paid
- Conflicts
- The authors declare no conflicts of interest.
- Authors work at
- Ahvaz Jundishapur University of Medical Sciences, Iran; University of Malaya, Malaysia; Islamic Azad University, Iran
The paper
- Title
- Effects of Citrulline or Watermelon Supplementation on Body Composition: A Systematic Review and Dose-Response Meta-Analysis
- Type
- Systematic review and meta-analysisThe authors follow a set, published method to find every relevant study, then combine the numbers from them into one result.
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Ashtary-Larky D, Mohammadi S, Mousavi SAH, et al (2025). Effects of Citrulline or Watermelon Supplementation on Body Composition: A Systematic Review and Dose-Response Meta-Analysis. Nutrients. doi:10.3390/nu17193126Free full textPubMed 41097202DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error