This week, we’re sharing another collection of oldies-but-goodies—pieces from our newsletter archive that address a variety of topics of continued interest to our audience. Some provide additional context for recent or upcoming content; some address frequently asked questions; and some are simply worth repeating for anyone who might have missed them. In honor of the new year, we’re focusing this collection on two common target areas for new year’s resolutions: nutrition and exercise.
The world of biomedical science is constantly evolving, but in evaluating what has changed, we like to pause now and then to acknowledge information and ideas that have remained relevant despite the passage of time—a celebration of “aging well,” if you will.
Adopting a new diet is a popular new year’s resolution for those seeking to improve their health, but given the amount of conflicting and misleading nutrition advice to which we’re constantly exposed, it’s often difficult to tell what changes might truly support a longer, healthier life. Indeed, a common resolution is to cut down on meat consumption or stop altogether, a decision often based on the perception of meat as an agent of disease and mortality. Yet meat’s negative reputation is hardly justified. It stems from a long history of observational research such as the study discussed in this 2024 newsletter on meat intake and diabetes risk—in which cherry-picked data and biased study groups were mistaken for causal associations.1
Dietary changes can be an impactful tool for improving health, but we need to be cautious that the changes we’re making are based on rigorous science, not overhyped and misinterpreted correlations. For guidance on choosing a diet that works for you and your health needs, we recently released an AMA in which we provide a framework for evaluating various nutritional approaches and use it to discuss potential advantages and disadvantages in a handful of popular diets.
Muscle strength is a topic we return to often in our content, as it is critical for maintaining health and physical function. (This past spring, we released an AMA designed to organize and streamline much of our back-content on strength and strategies for building and maintaining muscle mass.) But muscle mass and muscle quality tend to decline with age, resulting in a parallel decline in functional capacities, increased risk of falls and injuries, and reduced metabolic health.
However, age-related changes in muscle are not as unavoidable as we might have previously imagined. We know that resistance training can help to preserve muscle mass, but as discussed in this piece two years ago, research has shown that it also appears to slow or even reverse progressive deformation of muscle fibers—signifying that resistance exercise can also preserve muscle quality.2 Thus, although morning jogs or biking to work tend to get most of the attention when it comes to exercise resolutions, this newsletter reminds us not to neglect strength training as a vital component of any effort toward building a longer and healthier life.
Every year or so, popular media spreads the alarm that one sugar substitute or another poses some new threat to human health—usually based on shaky data from animals or epidemiology. Such was the case in March 2023 following publication of a paper seeming to show that the low-calorie sweetener erythritol raised risk of cardiovascular disease.3 In our subsequent commentary on this research, we pointed out why the results were misleading, and the critique serves as a timeless reminder to view flashy nutrition headlines with a healthy dose of skepticism.
Still, while we may not need to worry about erythritol and cardiovascular disease, sugar substitutes as a broad class occupy a controversial space in health and nutrition. To those interested in understanding various types of sweeteners and how the contexts in which they’re used can impact effects on health, we encourage you to check out our AMA episode on sugar and sugar substitutes from this past summer.
Given the positive feedback we received in response to last year’s AMA on strength and muscle mass, we recently took a similar approach with another key facet of exercise—cardiorespiratory fitness (CRF), which is a function of both aerobic base/endurance and maximal aerobic capacity. We distilled dozens of hours of information on understanding, assessing, and training CRF into clear, organized takeaways and guidance, and the resulting CRF AMA is scheduled for release next week.
However, in prioritizing actionable insights, we were left with limited time to dive deep into why CRF is so important from a longevity and healthspan perspective. Thus, we are re-sharing this premium article from April 2024 to help fill some of the gaps. The piece focuses on the maximal aerobic capacity side of the CRF formula, detailing why it is the most powerful predictor of health and lifespan that we have at our disposal. It serves as a handy primer for the upcoming AMA, especially for those who might be newer to our content. (For those interested in learning more about the aerobic base side of CRF, check out our follow-up premium piece on Zone 2.)
The limitations of epidemiology—and in particular, nutritional epidemiology—have been recurring themes across our content. Research in this field typically employs study designs that leave ample room for bias and confounding, and strictly correlational results are often inappropriately interpreted as evidence of a cause-and-effect relationship between variables. Every week brings a new load of flawed epidemiology studies from which we can draw no useful information, and we usually only bother to address them at all if they’ve captured media attention or we receive direct questions from our audience (such as with the other nutrition newsletters we’ve shared in this “oldies-but-goodies” edition).
But two years ago, we came across a study that exemplified such a broad range of missteps in scientific research and logic that it served as a perfect opportunity to show readers many of the flaws to watch out for when encountering headlines and articles about nutritional epidemiology.4 In fact, the study was so awful on so many accounts that it became almost comical, and indeed, across our entire catalog of weekly newsletters, few have been more fun to write than this critique. We hope that it gives you a laugh, but more importantly, we share it again now to help empower you to discern for yourself what is valuable in nutrition research and what is merely hype or click-bait. The new year will undoubtedly bring more scientific misinformation across a range of subjects, but the flaws are often remarkably consistent. Practice spotting them, and you can begin cutting through the noise and focusing more on the information that matters.
For a list of all previous weekly emails, click here.
References
1. Li C, Bishop TRP, Imamura F, et al. Meat consumption and incident type 2 diabetes: an individual-participant federated meta-analysis of 1·97 million adults with 100 000 incident cases from 31 cohorts in 20 countries. Lancet Diabetes Endocrinol. 2024;12(9):619-630. doi:10.1016/S2213-8587(24)00179-7
2. Soendenbroe C, Karlsen A, Svensson RB, Kjaer M, Andersen JL, Mackey AL. Marked irregular myofiber shape is a hallmark of human skeletal muscle ageing and is reversed by heavy resistance training. J Cachexia Sarcopenia Muscle. 2024;15(1):306-318. doi:10.1002/jcsm.13405
3. Witkowski M, Nemet I, Alamri H, et al. The artificial sweetener erythritol and cardiovascular event risk. Nat Med. 2023;29(3):710-718. doi:10.1038/s41591-023-02223-9
4. Klinedinst BS, Le ST, Larsen B, et al. Genetic factors of Alzheimer’s disease modulate how diet is associated with long-term cognitive trajectories: A UK Biobank study. J Alzheimers Dis. 2020;78(3):1245-1257. doi:10.3233/JAD-201058
