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A need to reconsider the definition of ‘healthy participants’ in epidemiological studies and clinical trials

European Journal of Clinical Nutrition volume 68, pages 724–725 (2014)Cite this article

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Health is defined as the absence of disease with a state of physical, mental and social welfare.1 Overweight and obesity describe weight ranges that are above the healthy limits, and are frequently assessed by body mass index (BMI) and also by waist circumference (WC) and body fat percentage.2 BMI provides a rough estimate of the body fat percentage for most people, with few exceptions as in the case of athletes (it overestimates fat mass) and older people (it underestimates fat mass). Central body fat distribution has been regarded as an important predictor of chronic disorders such as cardiovascular diseases and type 2 diabetes. WC is highly correlated with abdominal fat, and is considered a surrogate indicator of central fat mass.3 WC is a better predictor of the risk of diseases than BMI.4 However, because of the lack of a uniform protocol for the measurement of WC,5 it has not been extensively adopted, and BMI is still the most widely used tool for assessing weight status. A BMI between 25 and 29.9 is considered overweight, whereas a BMI over 30 is regarded as obese.2

Overweight and obesity are two stages that can hinder the normal body actions and increase the risk of several diseases such as cardiovascular disorders, type 2 diabetes, cancer and musculoskeletal disorders.2 Moreover, obesity has been reported to affect mental health6 and to interfere with muscle function and strength, possibly leading to impaired physical movement.7 Risks associated with excess body weight start at the overweight stage, increase with increasing weight,8 and raise the medical care costs that largely outweigh those of the normal weight population.1

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Acknowledgements

I thank Dr Sandra Drummond for reviewing the manuscript.

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  1. Department of Dietetics, Nutrition and Biological Sciences, Queen Margaret University, Musselburgh, UK

    G Farhat

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  1. G Farhat
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Correspondence to G Farhat.

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Farhat, G. A need to reconsider the definition of ‘healthy participants’ in epidemiological studies and clinical trials. Eur J Clin Nutr 68, 724–725 (2014). https://doi.org/10.1038/ejcn.2014.57

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