Competing Pardigms

As of this writing, the dominant theory on human health appears to be: Eat very little, limit carbohydrates, and do mostly strength training. Or, perhaps it would be more accurately summarized: ketosis and weight lifting.

Advocates of this approach recommend training your body to metabolize protein and fat in its resting state, so that you don't risk carrying a lot of body fat. While many people who follow keto-style diets don't have the whole story on why cardiovascular exercise is generally avoided by keto practitioners, the idea there is that, since cardiovascular exercise promotes fat matabolism, and therefore some fat storage, cardiovascular exercise is bad for losing weight. Besides, many will continue, weight lifting burns just as many calories and building more muscle mass means increasing your body's Basal Metabolic Rate (BMR). So, even though exercising doesn't hold a candle to dieting for weight loss, building more muscle mass is better than not building that muscle mass. Even if the BMR boost is small, it's still positive. Meanwhile, remaining in ketosis will take care of all that pesky fat tissue. Play your cards right, and you'll soon look like Ronnie Coleman, or so the argument goes.

(Never mind that Ronnie Coleman never actually ate like that.)

Under this paradigm, a person will eat mostly meat and vegetables, and very little of anything else, while doing some daily weight lifting. This is certainly a much healthier lifestyle than the average American is currently living, so if you're the kind of person to whom this lifestyle appeals, I say go for it.

Even so, I'd like to present you with a viable alternative that is at least as healthy, and possibly a lot healthier. That lifestyle can best be summarized as: do a lot of hard cardiovascular training, and eat a Mediterranean/DASH type diet consisting of lean meats, plant-based unsaturated fats, and whole grains. And don't go into ketosis.

The first reason I recommend this kind of lifestyle over the keto/weight-lifting lifestyle is because it is precisely the kind of lifestyle recommended by every doctor and dietician worth their salt. The second reason is because it is the only diet and fitness lifestyle that is consistently supported by scientific evidence.

But if that isn't enough to convince you, then consider a few more things.

Let's tackle the question of burning fat. A keto practitioner aims to burn fat and metabolize protein while his body is at rest. An endurance athlete, by contrast, aims to burn fat during exercise. The sweet-spot for this starts after twenty minutes of cardiovascular exercise and continues for up to about ninety minutes before tapering off. So, any cardiovascular activity you engage in that lasts between 20 and 90 minutes will primarily metabolize fat. If you have 45 minutes today, you can burn a bunch of fat cells and still eat fruit and drink milk and have a little pasta. There is no need to sacrifice pleasant and healthy food like blueberries and whole grain toast in order to burn fat off your body. You just need to spend between 20 and 90 minutes, several times per week, burning fat as fuel for exercise.

I grant that ketosis will enable you to do this while at a resting state. But the science of the matter is that you don't have to, and having that other option just might appeal to you. Especially if you like fruit.

What about increased muscle mass and an elevated BMR? Won't you have to give those up if you focus on cardiovascular exercise? No. The reason is because cardiovascular activities like running, swimming, and cycling still build lots of muscle; it just happens to be a smaller-yet-denser muscle tissue, compared to the hulky fast-twitch tissue required for weight lifting. In other words, endurance athletes still have more muscle mass and higher BMRs than sedentary people, even though their muscles appear smaller.

You might prefer the aesthetic appearance of a linebacker to that of a marathoner, and if so, more power to you. Lift weights. But, if you've been eschewing cardio exercise under the impression that you won't be as healthy as you will if you stick to weight lifting, then I have some good news for you: Do all the cardio you want, you'll still build muscle mass and enjoy a higher BMR.

A final important consideration here is the impact of cardiovascular fitness on longevity. As of my writing this, there is little evidence to support the notion that lifting weights extends your lifespan; but there is solid evidence in favor of the notion that cardiovascular health makes you live longer. So, if your goal is not only to lose weight and be healthy, but to live a longer life, cardiovascular exercise offers you something keto + weight lifting cannot.

So, which paradigm is for you? Burn fat while resting and never eat a carbohydrate? Or burn fat while exercising and eat tons of fiber? The choice is yours. I know what I've chosen.