Critical-appraisal

Weight loss product and programme reviews are subject to numerous biases that make them unreliable guides to what actually works. This article explains the specific sources of bias in consumer reviews, how to identify them, and where to find more reliable evidence.

Online reviews of slimming products are systematically biased by selection effects, publication bias, and commercial incentives. This article explains the specific mechanisms that distort diet product reviews and provides a framework for identifying whether a weight loss approach has genuine evidence.