It was said to me as a matter of fact. That the name of this column has the word fitness in it, not food, yet far more of the articles are about diet and nutrition than exercise.

I wasn’t asked why, so I didn’t reply. But I did do a good deal of thinking about it later.

After all, it’s another matter of fact that exercise has been associated with a surfeit of health benefits, such as lessening the incidence of many diseases as well as their severity if they do occur.

Then there’s what none other than Dr. Peter Attia has said about exercise in one way or another dozens of times, including when Dr. Matt Kaeberlein, professor of pathology at the University of Washington, appeared on Attia’s podcast, The Drive.

Attia - trained to be a medical surgeon and author of the New York Times Bestseller, Outlive: The Science and Art of Longevity - believes that exercise, not diet and nutrition, is the most critical factor for not only increasing lifespan, but also increasing healthspan. A term Kaeberlein defines in an August 2018 GeroScience article as “the period of life spent in good health, free from the chronic disease and disabilities of aging.”

Moreover, Attia shares another view with Kaeberlein on episode 222 that I hold, too. That as time goes on and the number of seemingly contradictory studies about diet and nutrition accrue, he views fewer and fewer things about either with certainty.

So why so many Fitness Master articles about diet and nutrition?

Because in the poker game of health, performing exercise is akin to drawing a king, queen, or ace. Experimenting with your diet is more like hoping the numbered card you hold becomes the wild card.

The analogy makes sense in part because of something I’ve written about in the past. That a lack of consensus in diet and nutrition studies has to be accepted to some degree since no two people process food in quite the same way.

So when a recent diet study corroborated the findings of previous ones by using sets of twins, this column quickly becomes the kindhearted poker dealer who makes sure that potential wildcard winds up in your hand.

In this specific study, researchers at Stanford University recruited 22 pairs of twins, average age about 40, and then had one twin eat one of two diets for eight weeks. Both diets were healthy, according to the press release, and “replete with vegetables, legumes, fruits and whole grains and void of sugars and refined starches.”

The difference?

One was entirely plant-based. The other also included chicken, fish, eggs, cheese, and dairy foods.

The use of twins “allowed researchers to reduce variables, such as genetic differences, upbringing, and lifestyle choices” - thereby diminishing the degree of uncertainty inherent in dietary studies Attia and others find so frustrating.

For the first four weeks, both groups had breakfasts, lunches, and dinners delivered to them, instructions on what snacks to eat, and on-call assistance from a registered dietician. For the next four weeks, they prepared their meals themselves with the registered dietician’s help.

The paper published online by JAMA Network Open in late November states that weight loss during the study “was not discouraged,” but that it wasn’t the goal either. In fact, participants were instructed to eat “until they were satiated throughout the study.”

So, it’s noteworthy that the twins on the vegan diet lost on average 4.2 pounds more than their counterparts.

When lead author, Dr. Christopher D. Gardner, Ph.D., a nutrition scientist at the Stanford Prevention Research Center in the Department of Medicine in the School of Medicine at Stanford University, spoke to Medical News Today about the study, though, he didn’t consider the weight loss difference to be as big a surprise as the average difference recorded in the LDL-cholesterol and insulin levels between the groups, which he deemed “significant.”

After all, he explained, the omnivore diet was designed to be healthy, so much so that it increased the group’s ingestion of vegetables and whole grains while decreasing their use of added sugars and refined grains “compared to their pre-study diet.” Yet the reduced levels of LDL-cholesterol and insulin suggest, as he writes in the JAMA article, a “significant protective cardiometabolic advantage” to a healthy vegan diet when compared to a healthy omnivorous one.

But you enjoy eating meat and animal-based products and don’t want to stop, you say. Gardener acknowledges most people feel the same, and addresses that in the press release by stressing “what’s more important than going strictly vegan is including more plant-based foods in your diet.”

So even if Attia is right and exercise has more influence on increasing lifespan and healthspan, that doesn’t mean you should dismiss the importance of a good diet. In fact, the twins study shows nearly the opposite.

That tweaking an already healthy diet can make good health even better.