Is Leaky Gut Test useful for weight loss?

The usefulness of a Leaky Gut Test for weight loss is not supported by current scientific evidence. Such tests (e.g., zonulin, lactulose/mannitol) are often marketed by functional medicine or direct-to-consumer labs, but their clinical validity for diagnosing 'leaky gut' is controversial. No robust studies demonstrate a causal link between increased intestinal permeability and weight loss. Weight management is primarily driven by energy balance, diet composition, physical activity, and behavioral factors. Even if permeability is altered, it remains unclear whether correcting it leads to meaningful weight reduction. The evidence level is best described as 'unclear' or 'marketing'. Consumers should not rely on these tests for weight loss; instead, they should focus on evidence-based approaches. If gut issues are suspected, a physician should be consulted for proper diagnostic workup (e.g., for celiac disease or IBS).