Myth: A low BMI is indicative of a healthy lifestyle, and a lower mortality risk.
Truth: This is false.
Body mass index (BMI), although commonly used to assess a person’s health, is not always reflective of their lifestyle or their risk of mortality – a lower BMI does not always mean that a person lives a healthy lifestyle and is at a lower risk of mortality. In a study published in the British Medical Journal, researchers discovered that a lower BMI was only associated with a lower risk of mortality if the individual was also living a healthy lifestyle. If the individual had a low BMI, but whose lifestyle was unhealthy (such as smoking or not exercising), they had a higher risk of mortality than individuals with a high BMI who were healthy.
Researchers concluded that those with a high level of physical activity, healthy diet, moderate alcohol consumption, and non-smoking benefited from having a lower BMI in relation to their risk of mortality. Those with unhealthy lifestyle choices who had a low BMI were at a higher risk of mortality than overweight individuals. Although it is commonly thought that overweight individuals have the highest risk of mortality, the results of this study show that lifestyle factors may be more important to the relative risk of mortality than weight alone.
Reference
- Veronese N, Li Y, Manson JE, Willett WC, Fontana L, Hu FB. Combined associations of body weight and lifestyle factors with all cause and cause specific mortality in men and women: Prospective cohort study. BMJ. Published online 2016:i5855. doi:10.1136/bmj.i5855
