Why You Shouldn't Burn More Than 4,000 Calories a Week Through Exercise

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by Mark Sisson Mark's Daily Apple

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Everyone agrees that being sedentary is bad and unhealthy and that being active is good and healthy. The research agrees, too; regular physical activity leads to good health, longer lives, and an improved ability to function throughout normal life. When you’re able to walk to the store, carry your groceries home, take the stairs, get out of bed without struggling, pack enough lean mass to survive a stay in the hospital, and ride your bike when you want to, you’re a functional human being, and remaining active on a regular basis helps maintain this state so crucial to basic health and happiness.

But what’s often hidden amidst the blanket pro-exercise sentiment is that too much exercise can have the opposite effect on health — people can really take physical activity too far. I talk about this all the time, so much that you’ve probably got “Chronic Cardio” emblazoned across your brain and shake your head when you see some hapless soul in spandex and the latest runners heaving himself down the street, heel first. I know just how bad that stuff can be, because I did it for a large part of my life. You’ve all heard that story before, though, about how even though training cardio hard gets you “fitter” in one sense of the word, it’s actually counterproductive for a healthy long life (doubly so if you want to have some lean muscle mass and pain-free joints in your later years).

We’ve seen hints in studies over the years:

One recent study found that in overweight sedentary subjects, moderate exercise was more efficient at helping them burn body fat — including a reduction that was far greater than what could be explained by the caloric expenditure — while intense exercise induced a “compensatory” response that hampered fat loss.

Another study examined weekly caloric expenditure via aerobic exercise in a group of former athletes and non-athletes and plotted it against mortality, cardiovascular disease, and hypertension. Death rate was highest in groups 1 and 2, the ones with the least amount of caloric expenditure, but group 6 (along with 1), which expended 2,500+ calories per week, had the highest rates of heart disease and high blood pressure. Those who exercised moderately lived the longest and were healthiest.

In a study on the exercise habits of college alumni and their impact on mortality, researchers found that up to 3,500 calories expended per week conferred a survival benefit, but at calorie expenditures greater than that, mortality began to tick upwards.

And in a pair of recent studies, researchers found that moderate exercise — jogging up to 20 miles a week at an 11 minute mile pace — offered the most protection against early mortality. Running more than 20 miles a week, or running at a 7 minute mile pace, offered fewer mortality benefits. In the second paper, Danish scientists found that people who spent one to two and a half hours jogging at a “slow or average pace” lived longer than those who didn’t run at all or who ran at a faster pace. James O’Keefe, a cardiologist and presenter at the Ancestral Health Symposium, was quoted as saying that “after about 45 to 60 minutes a day, you reach a point of diminishing returns.”

It’s pretty clear that once exercise gets to be “too much,” the benefits are reduced, or even reversed, and it becomes a chronic stressor that reduces overall wellness.

And so I thought it’d be helpful to give you guys a guideline for determining just how much is too much. This is a guideline I’ve had great success with, whether I’m training myself or clients: no more than 4,000 calories expended through focused exercise per week.

Is this a hard and fast rule? No, not exactly. Going somewhat above is probably okay.

Is it concretely established in numerous studies? There are hints toward its veracity in the literature, but nothing explicit. This is mostly stuff gleaned through experience (but the research does bear it out).

Does it apply to everyone, everywhere, whatever their goals may be? No. Someone training for the Hawaii Ironman Triathlon is going to require more if they hope to compete.

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