The Panacea of Human Aging

Calorie Restriction Versus Exercise

Nicholas T. Broskey; Kara L. Marlatt; Jasper Most; Melissa L. Erickson; Brian A. Irving; Leanne M. Redman

Disclosures

Exerc Sport Sci Rev. 2019;47(3):169-175. 

In This Article

Conclusions

To test our hypothesis that CR is superior to exercise as an anti-aging intervention, we evaluated the effects of CR and exercise on determinants of primary and secondary aging through critical review of the literature. Whereas exercise is more important for maintaining overall fitness and strength, we recommend initial weight loss through CR and maintenance of this weight loss with increased exercise in a dose-dependent manner. Appropriate application of either intervention should take an individual's age and health status into account and whether it is sustainable. Interventions will only be as effective as the overall compliance of the individual. Long-term sustainability should be assessed, as compliance determines the effectiveness of an intervention. Young and middle-aged adults may receive the most benefit from CR as a lifespan extension strategy, compared with older adults. The modern obesogeneic environment is another factor that should be considered. Given the widespread accessibility of calorically dense foods, CR is the most efficacious lifestyle intervention for those individuals that have clinically relevant amounts of adiposity to lose. Alternatively, exercise may be more appropriate for elderly individuals, as it preserves lean muscle mass, improves strength, and decreases fragility. Overall, more RCTs combining both CR and exercise are needed across multiple time points throughout life and in various metabolic disease states to ensure the most adequate weight loss recommendations are prescribed. In addition, future efforts should aim to identify primary physiological and behavioral determinants of long-term adherence to healthier lifestyle choices across the lifespan.

To conclude, we found more evidence to support that CR, but not exercise, reduces metabolic rate and lowers oxidative stress in humans, and thus seems more effective for attenuating determinants of primary aging (Figure 2). CR may be a superior lifestyle modification strategy to improve healthspan and promote longevity via reductions in metabolic rate and oxidative stress, whereas clinical trials of exercise do not consistently demonstrate these improvements. In regards to secondary aging, we found that both CR and exercise beneficially reduce adiposity. Taken together, the current state of the literature suggests that CR leads to more robust and sustained improvements in primary and secondary aging factors than exercise. Thus, CR may be a superior lifestyle modification strategy to improve healthspan and promote longevity via reductions in metabolic rate and oxidative stress, whereas clinical trials of exercise do not consistently demonstrate these improvements. More long-term studies are needed to fully elucidate the synergistic and separate effects of either lifestyle modification approaches on human aging and to identify strategies to predict adherence.

Figure 2.

Schematic diagram representing the effect of calorie restriction (CR) and exercise on components of primary and secondary aging. Primary aging is the progressive physiological decline, which depends on body functioning and depends on one's metabolic rate and oxidative stress. A. CR exerts its effect on primary aging via reductions in energy intake and subsequently less flux of macronutrients through the mitochondria. B. In turn, mitochondria release less reactive oxygen species (ROS) inducing a state of less oxidative damage to DNA. C. On the other hand, exercise increases energy expenditure, which increases energy flux through the mitochondria and leads to higher generation of ROS and oxidative damage D. Secondary aging is defined as untoward change in body composition and metabolic function. E. In regard to secondary aging, CR has been shown to improve biomarkers associated with cardiovascular disease (CVD) and reductions in adiposity. These reductions are primarily through decreases in both (F) visceral adipose tissue and (G) subcutaneous adipose tissue (H). However, CR also leads to loss of fat-free mass (muscle and bone). Likewise, exercise has shown to improve biomarkers associated with CVD (E) and reduces adiposity (F, G), albeit not to the extent of CR, but maintain fat-free mass (I). EE, energy expenditure; EI, energy intake; VAT, visceral adipose tissue.

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