Cardiovascular disease (CVD) is defined as disease that affects the heart and blood vessels. Common CVD conditions include atherosclerosis (plaque buildup), myocardial infarction (heart attack), heart failure, and stroke. Lifestyle interventions such as increased physical activity, healthy dietary modifications, and a reduction in alcohol consumption and smoking, have long been implemented to reduce CVD risk. These lifestyle interventions have been shown to have an impact on risk. One meta-analysis on the subject concluded that adherence to two or more lifestyle factors was associated with a 66% relative risk reduction in CVD risk compared to adopting none or only one behavior (1). What I want to dissect further here is the degree of importance that weight loss and BMI maintenance has on cardiovascular health and associated health outcomes (e.g. cardiovascular events and mortality).

First, let's define BMI. For those who don’t know, BMI or Body Mass Index is calculated based on an individual’s height and weight. BMI is then categorized into ranges; either ‘underweight’ (BMI <18.5), ‘normal weight’ (18.5-24.9), ‘overweight’ (25-29.9), or ‘obese’ (>30). BMI measurements are notorious for being somewhat inaccurate since they fail to account for age, sex, body composition, and other factors that may convey a better representation of health. For example, falling into the ‘overweight’ may sound unhealthy, but if you’re a bodybuilder with 5% body fat then that may not necessarily be the case.

This is where looking at the research and using BMI to describe risk of specific disease outcomes is exciting, and may be more beneficial than aiming for a ‘normal’ BMI. In the context of cardiovascular disease, it has actually been found that those individuals with existing coronary artery disease and low BMI (<20) had an increased relative risk for cardiovascular mortality and total mortality (death from any cause) (2). In this same systemic review of the literature, overweight individuals (BMI 25-29.9) had the lowest risk of mortality from CVD and all other causes compared to individuals with a BMI in the normal range (2). The interpretation here may be that there is no reason to aggressively push weight loss in some individuals for the purpose of cardiovascular health alone. Although to the author’s point, BMI may not discriminate accurately enough between body fat and lean body mass.

Another study looking at the effects that BMI has on mortality in both men and women aged 70-75 found again that mortality risk was lowest in overweight individuals (13% less than normal-weight individuals), and that risk of death was similar for normal-weight and obese participants (3). Interestingly, being sedentary was associated with increased mortality in both men and women across all levels of BMI; therefore it’s reasonable here to conclude that BMI thresholds may be too restrictive, especially in the elderly (3).

Bottom line: too much emphasis may be placed on meeting weight loss and BMI targets with insufficient evidence to back these goals up. Current research actually points to more forgiving BMI ranges in older adults, and potentially some benefit in being in the ‘overweight’ BMI category. Instead, it may be best to focus lifestyle efforts on increasing fruit and vegetable intake as a part of a balanced diet, maintaining an active lifestyle, and reducing harmful behaviors such as heavy alcohol use, smoking, and stress (4). This strategy may also help those who are having difficulty losing weight remain motivated to continue beneficial habits. As always, please speak with your doctor before beginning any lifestyle interventions since individual situations must be considered.


Author: Emily Howard, ND, BSc


References
1. Barbaresko J, Rienks J, Nöthlings U. Lifestyle Indices and Cardiovascular Disease Risk: A Meta-analysis. Am J Prev Med. 2018;55(4):555-564. doi:10.1016/j.amepre.2018.04.046
2. Romero-Corral A, Montori VM, Somers VK, et al. Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies. Lancet. 2006;368(9536):666-678. doi:10.1016/S0140-6736(06)69251-9
3. Flicker L, McCaul KA, Hankey GJ, et al. Body mass index and survival in men and women aged 70 to 75. J Am Geriatr Soc. 2010;58(2):234-241. doi:10.1111/j.1532-5415.2009.02677.x
4. Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies. Int J Epidemiol. 2017;46(3):1029-1056. doi:10.1093/ije/dyw319