Harvard Health Columns

The science of exercise shows benefits beyond weight loss

Staying active resets your body's biochemical balance.
Key point: Go easy, but go consistently.

Exercise is even better for you than you think. Exercise has effects right down to the subcellular level. For example, mitochondria—the power plants inside each cell in the body—appear to be more efficient at burning off fatty fuel in active people. They have lower blood levels of branched-chain amino acids (BCAA), which accumulate in the blood of people who are obese or who have diabetes.

Researchers have theorized that the healthier our mitochondria are, the less likely we are to develop a variety of age-related diseases, including diabetes, heart disease, Parkinson's, and Alzheimer's disease. Exercise could lead to the better overall health of a person specifically by acting on the mitochondria.

Beyond weight loss

As scientists explore exactly what it is that exercise does, they're finding a surprising list of physical effects that go far beyond weight loss and muscle building. These include increased insulin sensitivity (meaning a lower risk of type 2 diabetes), lower cholesterol levels, a better ratio of saturated to unsaturated fats, and biochemical markers of lowered cardiovascular risk. People who exercise regularly also have blood amino-acid profiles linked to good heart health.

Everybody can benefit from exercise at any age, even if a person has a chronic disease. People with cardiovascular disease stand to gain substantially from a regular exercise routine.

Even people of advanced age who've already had a heart attack are 20% less likely to develop serious heart trouble if they participate in an aerobic exercise–based cardiac rehabilitation program.

What exercise does

Many of the benefits of exercise have been known for quite a long time. Exercise reduces weight, lowers blood pressure, prevents diabetes, improves cholesterol, increases muscle strength, improves sleep quality, improves mood, and even sharpens the mind.

But these are all just the signs of the multisystemic benefits of exercise. What we still don't know is exactly how exercise is able to bring about all these wonderful benefits.

How much exercise is enough?

Most experts say a person should get in at least 30 minutes of exercise nearly every day of the week. This can sound very daunting to a lot of people. If exercise is new for you, don't try to hit your goals right away. Get started, even if that means just walking for 10 minutes.

How hard should you work out? Not so hard that it stops being fun. Consistent moderate activity is better than occasional strenuous activity.

It's better to take a brisk walk every day than to do a hundred-yard dash once a week.

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