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Spirulina, Weight and Metabolic Health: Research Overview
Trials have examined spirulina supplements and body-weight measures. They do not show that SPRU causes weight loss or treats obesity.
Meta-analyses have pooled trials of spirulina supplements and body-weight measures. A 2020 review reported a small average reduction in weight and waist circumference, with substantial variation between studies; it found no significant overall effect on BMI. A 2025 review of different algae supplements reported small average changes in several measures, but rated the certainty for those outcomes low or very low. Read the 2020 spirulina review · Read the 2025 algae review.
These results do not show that SPRU causes weight loss. The studies used supplements and varied in product, dose, duration and participants. SPRU is a food, not a weight-management treatment.