The Keys to Longevity

By Tim Caffrey, MD – July 31, 2020

We should not want to simply live for a long time; we should want to be healthy, vibrant and thrive as we age. How do we achieve this? A quick Google search yields hundreds of hits. Some are valid, but many are fueled by magical thinking, bad science and false promises. The good news is that there are legitimate ways to extend your lifespan, help you be healthier and have more energy and focus as you age. Engaging those strategies for health helps you lead a happier, more productive and fulfilling life for as long as possible.

The most effective longevity gains are associated with habits and genetic advantages. It’s old news, but the avoidance of tobacco use is still the single most effective way to extend life. Specifically, those who avoid tobacco will, on average, live 10 years longer than those who don’t. That’s what changing a single habit can do. Of course, a genetic advantage is not so modifiable — an example being that women live, on average, three and a half years longer than men. While the reasons for this advantage are still being unraveled, they appear to primarily be genetic, not cultural — nature, not nurture. Yet while some genetic factors appear fixed, others may be more malleable, with genetic risks amplified by stress levels, inflammation and other modifiable factors.

Aside from quitting tobacco and having good luck when it comes to genes, there are other ways to boost one’s longevity. While some websites and anti-aging clinics may promote poorly researched pills with exotic-sounding ingredients and fountain-of-youth-type solutions to aging, weight and exercise are, without a doubt, important keys to extending and improving life. Both weight and exercise appear to optimize physiologic processes that promote health and longevity.

From studies of weight, specifically Body Mass Index (BMI), there is growing evidence that BMI is strongly correlated with longevity, but not in the way you might think. BMI is a calculation that relates weight to height. While “normal” BMI is defined as 18.5-24.9, the BMI levels associated with the lowest rate of mortality extend from the higher end of the normal range (about 22-23) through the middle of the “overweight” category (25-30). That sweet spot, roughly 22 to 28, is most closely associated with increased longevity. In the sweet spot, rates of diseases resulting in early death such as stroke, many types of cancer and heart disease are at their lowest levels. The reason that a BMI that is technically in the “overweight” range can be healthier than a low, “normal” BMI probably has to do with the failure of BMI measurements to capture the relative contributions of fat and muscle to total weight. The BMI measurements also fail to factor in the differences in the type and location of fat stores throughout the body. This suggests that BMI alone is an incomplete prognosticator of optimal health and longevity.

While BMI is one key driver of longevity, physical activity is the other. It is increasingly clear that physical activity as a therapeutic intervention for physical and mental health issues strengthens the body, calms the mind, improves flexibility and circulation, decreases inflammation, increases physical and mental resilience and promotes good sleep. The evidence demonstrating the positive relationship between physical activity levels and longevity is strong. The strength of this relationship is often measured in terms of cardiorespiratory fitness — the capacity of the heart to transport oxygen. The higher the level of cardiorespiratory fitness, the greater the impact on longevity.

Cardiorespiratory fitness can be measured in a laboratory through an expensive and time-consuming process. But you don’t have to go to a lab to determine yours. You can go online to the Norwegian University of Science and Technology (NTNU) fitness calculator, plug in different levels of physical activity and see how they affect your cardiorespiratory fitness age. In the results, a lower cardiorespiratory fitness age is better. Through this method, you can also model how an overweight person who exercises may outlive a skinny couch potato.

We know that exercise boosts longevity, but what type of exercise is likely to yield the greatest results? It’s too early to tell. There is an expanding body of research focused on identifying the ideal combination of style, duration, intensity and frequency of exercise. It may be that at some point, we will be able to tailor physical activity based on genotype for maximum return. Today, however, the honest answer is that the best type of physical activity for you is the physical activity that you’ll actually do.

The impact of diet on human health and longevity is also difficult to study in a controlled way, so most recommendations are drawn from large population studies (e.g. the Mediterranean Diet) or extrapolation from relatively small samples (e.g. intermittent fasting). As with exercise, there is probably no single answer, and advances in genetics and epigenetics may someday allow specification of the ideal diet for each individual — but we aren’t there yet. While we’re waiting, perhaps the best summary of how to eat for longevity is Michael Pollan’s seven-word maxim from his book 7 Rules for Eating: “Eat food. Mostly plants. Not too much.”

Beyond BMI, exercise and diet, there is a growing list of other lifestyle factors that may promote longevity directly or enable longevity through disease mitigation. These factors include sleep, sexual health, social connections, relationship health, mental health and cognitive engagement. The best advice for those interested in maintaining vitality into old age: Try to optimize in each of these important areas. If you’re doing a great job improving your physical fitness but haven’t fully processed some life traumas, don’t neglect your mental health. If you haven’t seen a doctor in a while, get in, take a baseline of your physical health and start refining it. Tend to your sleep, destress your life and seek to have healthy, supportive relationships. 

Engaging with a healthcare team to conduct a comprehensive health assessment, encourage thoughtful utilization of well-supported preventive measures and diligent avoidance of harmful practices can also add years. In short, tending to the basics and optimizing the key fundamental areas stands to give you the most impact in terms of current health and longevity.

Finally — especially in the midst of a national conversation about health equity — there is strong evidence that higher income levels, higher education levels and socioeconomic status can all impact longevity. The ways in which these factors influence health and health behaviors is an area of intense study for both healthcare researchers and public policy experts. While we often think of longevity as a personal goal, it can also be a public goal. Trying to balance out inequities could reduce stress in society, lessen traumatic experiences, improve a felt sense of safety and can help everyone live longer, happier lives.

The key to longevity is not a secret, and it doesn’t have to be complicated or expensive. Maintain a healthy weight, move every day, sleep, eat real food, stay meaningfully engaged with the world, take care of your mind, tend to your relationships and be a discerning consumer of quality, science-backed healthcare. I would add that helping to create a safer, more equitable world expands health benefits to all. Let’s hope that our genes cooperate and that we all have a chance to improve our own quality of life and that of those around us for a long time to come. 

Tim Caffrey, MD, is a primary care physician at Presence Wellness, an integrative wellness center supporting your health with the latest science. Sign up for a comprehensive health evaluation and ongoing access at


Related Articles