Dear Mr. Taubes,

I would like to begin by voicing my heartfelt approval of your work in scientific review. I feel certain that your books Good Calories, Bad Calories and Why We Get Fat will end up being two of the most important works in the field of health and nutrition in our lifetimes. That being said, I would like to call attention to what I feel is an egregious error in your analysis regarding exercise.

You have undoubtedly made your point regarding calories in/calories out. You've successfully built the scientific foundation of what many of us had experienced and intuitively felt for years regarding the futility of eating fewer calories and trying to burn more of them through what is being referred to as "chronic cardio". I even tentatively accept that the effect of increased muscle mass on caloric expenditure is negligible.

What you have completely failed to address is why exercise DOES work.

Oh, not all exercise for all people, but as you yourself have so effectively pointed out, a sound scientific theory should take all observable phenomena into account. Saying that people cannot change their physiques through exercise is as silly as saying that bees can't fly because of poor aerodynamics...or that fat makes us fat.

In 1991, back when I still knew everything, my Navy buddy and I had a ritual we followed virtually every workday: wake up at 5:00 am, run from the barracks to the pier, complete our workday, spend two hours at the gym, eat what we were convinced was a "healthy" dinner, and go to the bar to drink beer until closing time.

The run wasn't far - definitely less than a mile - but we ran as fast as we could with our backpacks full of our uniforms and sundry work items. We didn't know crap about lifting weights, but we tried to work hard there as well. We knew even less about the "cardio" that we did after the weights, but we spent a good 30-60 minutes every day on whatever machine struck our fancy, plodding along while we talked about how healthy we were.

Our "healthy eating" followed the conventional wisdom at the time: mostly vegetarian, with minimal amounts of fish or poultry a few times a week. VERY low fat. In fact, I had it in my head that the key point was reducing fat percentage as much as possible, which I would frequently do by INCREASING my carb intake with rice, beans, or even shoveling a half-loaf of bread with honey into my face if I felt I had had too much fat that day.

Through it all, I was convinced I was doing the right thing...because I lost fat. My pants fit more loosely, my girth measurements decreased, and my wedding ring would occasionally fly off if I gestured too emphatically.

This of course describes the experiences of a formerly sedentary mesomorph and a previously moderately-active meso-endomorph, both in our early 20s. But as a proof-of-concept, it shows that something was happening, and that "something" bears further investigation.

As time went on, I experienced greater and greater problems with this type of eating, until 1998 or so when I first read about something called the "Metabolic Diet" which forever changed my thoughts about food. Through the following 2 decades, my workouts changed and became more functional and less about physique. Through both of these progressions, my health, functionality and physique continued to improve.

The question remains, however, why did I lose fat in 1991?

I've seen it proposed in muscle magazines such as the online T-Nation that exercise helps improve insulin sensitivity, and that may ultimately turn out to be the determining factor. By inadvertently - and ignorantly - following a program that strongly resembles Mark Sisson's "Primal Blueprint" exercise regimen (spend a lot of time moving around slowly, pick up heavy things sometimes, sprint occasionally), perhaps we put ourselves in a better hormonal state to deal with the ridiculously high levels of carbohydrates we were taking in. Perhaps it's something else entirely.

And we're not the only ones I've seen this happen to. Most people experience some level of physique change when they first start doing any kind of high-intensity exercise, even with the Conventional Wisdom diets of low-fat and high-carbohydrates, although they soon stagnate and then regress. Adherents of CrossFit, the Primal Blueprint, kettlebell fitness, and even powerlifting- and Olympic-lifting-based workouts that include no "energy systems" work at all experience these changes to a much greater degree, as do military special forces members who are encouraged to eat their fill on carb-laden "energy foods".

Mr. Taubes, something happens when we exercise, beyond increasing our endurance and fitness and the opportunity to "simply feel better about ourselves" as you describe it. Rather than dismiss it as illusory, and explain to us how you've proven that the bumblebee cannot fly, please follow your own prescription of using relevant research to explain observed phenomena, or acknowledge that we don't yet know.

With respect and admiration,

    - Jonathan Sabar

    Owner, Sabar Function and Fitness, LLC