The Sunday Morning Post: Why Exercise Is a Miracle Drug

Plus: How to save 100 million lives with 1/400th of our income

Photo by kike vega on Unsplash

Welcome back to The Sunday Morning Post, this newsletter’s weekly rundown of the most interesting and important stuff I’m seeing in science, technology, economics, and beyond. Comments are open. Leave tips, papers, studies, tweets, posts, questions, and graphs in the comments, if you think they’ll serve for future editions.

We’re Never Going to Invent a Drug That’s Better Than Exercise

Euan Ashley has claimed that exercise is the “single most potent medical invention” ever—more broadly effective than any medicine discovered in the natural world or devised in a laboratory. In 2025, this is the sort of rah-rah sentiment about working out that one might associate with a Make America Healthy Again ambassador rather than, say, the chair of medicine at Stanford University. So, what makes Ashley’s claim significant is that he is the chair of medicine at Stanford University.

Last year, Ashley and a large team of scientists conducted an elaborate experiment on the effects of exercise on the mammalian body. In one test, Ashley put rats on tiny treadmills, worked them out for weeks, and cut into them to investigate how their organs and vessels responded to the workout compared to a control group of more sedentary rodents.¹ The results were spectacular. Exercise transformed just about every tissue and molecular system that Ashley and his co-authors studied—not just the muscles and heart, but also the liver, adrenal glands, fat, and immune system.

When I asked Ashley if it was possible to design a drug that mimicked the observed effects of exercise, he was emphatic that, no, this was not possible. The benefits of exercise seem too broad for any one therapy to mimic. To a best approximation, aerobic fitness and weight-training seem to increase our metabolism, improve mitochondrial function, fortify our immune system, reduce inflammation, improve tissue-specific adaptations, and protect against disease.

The latest entry in the Exercise Is Magic file comes from the New England Journal of Medicine. In a recent study, 900 cancer patients who had undergone surgery on their advanced colon cancer were randomly assigned to two groups. One group got a “structured exercise program.” They went to behavioral support sessions and attended supervised exercise classes every few weeks for several years. The other group received only basic information about diet and health.

Compared to the control group, the exercise group saw “significantly” more years without cancer, a 7 percentage point increase in the overall survival rate after 8 years, and a dramatic reduction in new primary cancers. Exercise, it seems, doesn’t just prevent disease; it can also save your life after you get sick.

The author Daniel Lieberman has put it well: Exercise is healthy and rewarding even though it’s something we never evolved to do. To adapt to the physical ease of the modern world, people invented a variety of weight-resistant devices and bodily movements that allow today’s population to simulate the arduous tasks that were once necessary to make it through a life, and this strange pantomime of physical stress seems to do more for us at a molecular level than any therapy or intervention in the history of medicine.²

How to Save 100 Million Lives

Soon after overseeing cuts to more than 80 percent of programs at the United States Agency for International Development, Secretary of State Marco Rubio said in remarks in July that USAID “has little to show since the end of the Cold War.” In the field of global health, this analysis may be off by about 100 million.

In June, The Lancet published an evaluation of 20 years of USAID funding by a team of global researchers from Brazil, Spain, Mozambique, and the United States. They calculated that US global health and development spending has spared about 90 million deaths in low-income countries, including:

• 25 million lives saved from HIV/AIDS

• 11 million from diarrheal disease

• 9 million from lower respiratory infections

• 9 million from "neglected" tropical diseases, such as dengue and river blindness

• 8 million from malaria

• 5 million from tuberculosis

• 2 million from nutritional deficiencies

All this was achieved with a program that accounts for about 0.8 percent of the federal budget and about 1/400th of America’s total national spending. This is a staggering return on moral investment.

When I think about the case for global health spending, I think about the first days of my life. Nobody chooses how they come into the world. I achieved nothing to earn my birth in a hospital in Washington, D.C., as opposed to a clinic in Maputo or Kinshasa, or to deserve the automatic guarantee of American citizenship upon my first breath of air. That I was born in the capital of the world’s richest country is one of the greatest strokes of luck in my life—a pure accident of timing and gametes. There is no way to pay back this good fortune, and wallowing in guilt over it would do nothing, either. The quiet miracle of charity and global aid is that the uneven distribution of global wealth creates an asymmetry by which relatively trivial amounts of money from the rich can prevent immense suffering and death among the poor. Interventions as simple as bed nets, antiretroviral therapies for HIV/AIDS, and the distribution of commonplace vaccines and therapies in impoverished rural areas can save an astonishing number of lives, while costing a rich country an amount of money that makes practically no difference to any their citizen’s day-to-day.

Americans are blessed to be in possession of a kind of sorcerer’s stone—a bit of policy alchemy that can transform one-four hundredth of our spending into 100 million saved lives, in less than half a century. I think we should use it.

1. Eventually, we should want to know whether this precise experiment replicates in humans. But it would be really rude to conduct Ashley’s intervention on people, since doing so would mean, let’s say, putting me on a treadmill for weeks and then slicing into my kidney to see how all that sprinting changed my adrenal gland tissue.

2. Just a thought bubble: Is there a good reason why Medicare and Medicaid don’t typically cover gym memberships?