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In their editorial, Malhotra et al 1 highlighted the important health benefits of physical activity in cardiovascular disease, type 2 diabetes, dementia and cancer, but dismissed any benefit for weight loss in obesity. However, the poor use of existing evidence to underpin this dismissal and the resultant press release generated headlines that could send a misleading message to patients and the public.
Poor use of evidence
An evidence-based approach to clinical decision-making involves understanding the best type of evidence to use, how to appraise it, and assessing its usefulness in practice. Such an approach determines the risk of bias and ensures decisions are guided by accurate, meaningful evidence. The GRADE guidelines cite expert opinion alone as very low quality evidence, with a high risk of bias.2 Unfortunately, much of the evidence cited by Malhotra and colleagues was based on expert opinion or was not referenced. For example, when excluding a relationship between obesity and physical activity, the evidence cited was an opinion piece by Luke and Cooper,3 which has been criticised for ignoring observational and experimental studies that support a relation between physical activity and obesity. They give no reference for their claim that, according …
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Competing interests KRM is an NHS general practitioner who supports and advises patients to lose weight through a healthy balanced diet and regular physical activity. He holds NHS National Institute of Health Research (NIHR) grant funding for some of his research. JMcM is Director of Public Health for Hertfordshire, and a member of the Academy of Medical Royal Colleges Health Inequalities Forum. He is a member of the International Scientific Advisory Group for the Centre for Diet and Activity Research at the University of Cambridge. DN is a senior research fellow and tutor of evidence-based medicine, with a background and research interest in exercise physiology and physical activity. He holds NHS National Institute of Health Research (NIHR) grant funding for some of his research. The views expressed are those of the author(s) and not necessarily those of the NHS National Institute of Health Research (NIHR) or employing institutions.
Provenance and peer review Not commissioned; internally peer reviewed.
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