This Is What Happens To Your Body When You Stop Exercising

We all know that regular exercise is extremely good for us. But what happens when you suddenly quit working out altogether?

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The benefits of physical activity are hardly permanent, and many of your hard-earned gains will disappear after just two weeks of being sedentary, says Farah Hameed, MD, a sports medicine physician with ColumbiaDoctors. TIME magazine spoke with Dr. Hameed to find out what happens to your body after you give up exercising — and his answers may surprise you.

Here’s exactly what happens to your body after you give up exercising.

10 Days: Your Brain Changes

When we think of exercise, we most often think of the benefits it has on our bodies, but research shows that regular physical activity has a huge effect on the mind as well. A new study found that even taking a short break from your regular fitness routine can trigger changes in the brain. The study examined a group of long-term endurance runners as they took a 10-day break from exercise. Researchers found that the runners had a reduction in blood flow to the hippocampus, the part of the brain that’s associated with memory and emotion.

Two Weeks: Your Endurance Plummets

Being sedentary for two weeks days will cause a drop in your VO2 max, or the maximum amount of oxygen your body can use, by about 10 per cent. This means you might get much more easily winded when climbing stairs or running to catch the bus, for example. It only gets worse the more time you spend inactive; after a month, your VO2 max can drop 15 per cent, and after three months it can fall nearly 20 per cent.

Thankfully, staying even slightly active can help. One 2009 study found that male kayakers who took a five-week break from training saw a 11.3 per cent drop in their VO2 max. Compare that to those who found a way to squeeze in a handful of exercise sessions a week; they saw only a 5.6 per cent drop.

But even if you don’t notice a difference in your speed or endurance, this is also the window in which you’re more likely to experience a rise in high blood pressure or blood glucose levels, especially if you’re prone to these issues.

Four Weeks: Your Strength Decreases

Unlike endurance, which plummets relatively quickly, strength tends to take a bit longer to decrease. It also declines at different rates for different people. Dr. Hameed estimates that most people will see a difference in strength from two to four weeks of inactivity. However one 2011 study in the Journal of Strength and Conditioning found that when a group of men quit doing resistance training, they still had some of their strength gains up to six months later.

Eight Weeks: You May Gain Fat

You’ll likely to notice a physical change after about six weeks of inactivity, whether that’s by a number on the scale or your jeans fitting a little bit tighter. The change can be especially noticeable in elite athletes, whose bodies have become accustomed to rigorous exercise. A 2012 study in the Journal of Strength and Conditioning Research found that competitive swimmers who took a five-week hiatus from training experienced a whopping 12 per cent increase in body fat, as well as overall body weight gain and larger waistlines (despite the fact that they still did some light and moderate exercise).

Of course, there’s a difference between completely falling off the exercise bandwagon and taking a well-deserved rest. For example, if you’ve just run a marathon, you may want to consider doing some HIIT training, strength training or light cardio a few times a week, rather than keeping up your rigorous race-training schedule.

“You need to do some type of activity [every day],” says Dr. Hameed. Whatever you do, keep moving. Your body will thank you for it.