Introduction:
If “An apple a day keeps the doctor away”, what can an hour of daily exercise do?
In my preventative healthcare conversations with patients, the topic of weight loss is often top of mind: “What can I do to lose weight?” “Will I be able to stop my blood pressure or cholesterol medications if I lose 20 pounds?” “How will my health improve with weight loss?” Though these are important questions to be asking, and the dangers of obesity are worth addressing, my response is often to draw attention to an even greater concern from my perspective: poor cardiovascular fitness.
The Case for Focusing on Fitness:
There have been several major, long-term, cohort studies conducted since the 1950’s that have aimed to capture the impact of various cardiovascular disease (CVD) risk factors such as obesity and cardiorespiratory fitness (CRF) on eventual development of CVD and/or premature mortality. Altogether, the evidence suggests a much stronger association between low cardiovascular fitness and increased mortality when compared to obesity and increased mortality.1-5
A study published in the Journal of American College of Cardiology (JACC) in 2023 looked at 93,060 individuals aged 30 – 95 who were a part of the larger ETHOS (Exercise Testing and Health Outcomes Study) Veteran Affairs cohort and had undergone exercise treadmill stress testing, assessing CRF as measured in metabolic equivalents of a task (METs). This analysis demonstrated a clear, inverse association between CRF and mortality risk: a decline in CRF of >2.0 METs in those with low fitness was associated with a 69% increased risk of mortality (HR: 1.69 (1.45 – 1.96)) for those without a history of cardiovascular disease (CVD) and a 74% increased mortality risk (HR 1.74 (1.59 – 1.91)) for those with CVD.1
A smaller cohort study of 2603 adults over the age of 60, conducted between 1979 – 2003, demonstrated CRF was a significant mortality predictor irrespective of BMI, waist circumference and body fat percentage.2
Lastly, the Henry Ford Exercise Testing Project, conducted between 1991 and 2009 and including 29,257 Americans with a mean age of 53 years without cardiovascular disease, demonstrated a strong, inverse correlation between cardiovascular fitness as measured in METs and all-cause mortality, with a Hazard Ratio (HR) of 0.86 (0.85-0.88). BMI was inversely related to mortality, but to a significantly lesser degree: HR 0.98 (0.97-0.99). This study demonstrated an “obesity paradox”, wherein the highest risk group were individuals with low exercise capacity (<10 METs) and low BMI, which was not observed in the higher exercise capacity, higher BMI group.3
Though there are limitations in assessing excess adiposity through BMI, which can be easily affected by other factors such as higher muscle mass, the evidence repeatedly suggests that poor exercise capacity is the bigger risk concern compared to obesity.
My Recommendation:
Though the potential health risks of obesity are not to be ignored, for the average individual, given the choice between recommending focus on cardiovascular fitness versus focus on weight loss through cutting calories, I would recommend the fitness focus. From my review of the literature, there is a much stronger body of evidence linking increased mortality risk with poor cardiovascular fitness when compared to obesity. By focusing on fitness, not only is potential longevity likely better protected, but excess weight will often be addressed in tandem.
References:
1. McAuley PA, Blaha MJ, Keteyian SJ, Brawner CA, Al Rifai M, Dardari ZA, Ehrman JK, Al-Mallah MH. Fitness, fatness, and mortality: the FIT (Henry Ford exercise testing) project. The American journal of medicine. 2016 Sep 1;129(9):960-5.
2. Sui X, LaMonte MJ, Laditka JN, Hardin JW, Chase N, Hooker SP, Blair SN. Cardiorespiratory fitness and adiposity as mortality predictors in older adults. Jama. 2007 Dec 5;298(21):2507-16.
3. Kokkinos P, Faselis C, Samuel IB, Lavie CJ, Zhang J, Vargas JD, Pittaras A, Doumas M, Karasik P, Moore H, Heimal M. Changes in cardiorespiratory fitness and survival in patients with or without cardiovascular disease. Journal of the American college of cardiology. 2023 Mar 28;81(12):1137-47.
4. Korpelainen R, Lämsä J, Kaikkonen KM, Korpelainen J, Laukkanen J, Palatsi I, Takala TE, Ikäheimo TM, Hautala AJ. Exercise capacity and mortality–a follow-up study of 3033 subjects referred to clinical exercise testing. Annals of medicine. 2016 Jul 3;48(5):359-66.
5. Clausen JS, Marott JL, Holtermann A, Gyntelberg F, Jensen MT. Midlife cardiorespiratory fitness and the long-term risk of mortality: 46 years of follow-up. Journal of the American College of Cardiology. 2018 Aug 28;72(9):987-95.