What really happens to your body when you don't exercise enough

Some people are born with naturally thin frames and the metabolism that allows them to eat whatever they want and never gain weight. It's tempting for these people to forego exercise altogether in favor of hanging on the couch and watching TV with a friend. As a certified personal trainer, I've had many clients who weren't convinced they actually needed to exercise since they were naturally thin.
Exercise does a lot more than help us burn calories to lose weight. In fact, not getting enough exercise can have a pretty significant impact on what's going on in our bodies and the future of our health. What really happens when you don't exercise enough?

You crave unhealthy food

Many people who exercise regularly also eat very healthy diets. While it may seem like this is always due to a conscious choice to be healthier, it turns out that people who are more active actually crave healthy food. This is called the transfer effect and refers to the effect whereby learning new skills and improving in one area of your life automatically triggers a desire for improvements in another. This is great if you're trying to build multiple healthy habits, like exercising and eating healthy.

The problem is, I've seen it work in the reverse for some of my clients as well. When someone falls off the wagon with their exercise routine, it doesn't take their nutrition long to follow. Your body stops craving highly nutritious foods because it no longer needs the extra sustenance. Instead, nutritionally-poor-but-delicious foods like potato chips and chocolate cake become quite enticing. Not only that, but it's a lot easier to eat a bag of chips while you're sitting in front of the TV binge-watching an entire season of your favorite show on Netflix than it is while you're at the gym. Once you start eating junk, you start craving more junk. Wouldn't it be easier to get regular exercise and let your body take care of the cravings itself?


You don't sleep well

Tossing and turning all night, but feel like you still have a ton of restless energy to burn? According to the Centers for Disease Control and Prevention (CDC), one in three American adults is not getting enough sleep. If you're someone who is experiencing sleep problems, you may not be exercising regularly enough.

Regular exercise has been shown to increase total sleep time and leave people feeling more alert and well-rested throughout the day. This has been shown even while controlling for Body Mass Index (BMI), health status, smoking status, and depression. What that means is that the positive effects of exercise on sleep aren't just because people who exercise more tend to have a lower BMI or tend to be healthier overall. Regular exercise can be beneficial for sleep for all of us, even those who suffer from insomnia. When you don't exercise enough, the benefits to sleep aren't as noticeable. While a single day of exercise does produce some small improvements to sleep compared to those who do not exercise, only those who engage in regular exercise see a significant difference in sleep quality. Can't sleep? It may be time to start exercising regularly!

You get winded easily

If you don't exercise regularly, you may find that when you climb a flight of stairs or carry a heavy bag of groceries for more than a few feet, you get out of breath. Regular exercise results in improved cardiovascular (heart and blood vessel) health and pulmonary (lung) health, leading to improved functional exercise capacity and reduced breathlessness in both healthy people and those with chronic lung conditions. This means your body has greater efficiency for taking in and absorbing oxygen, even when your body is fatigued. Without regular exercise, your body is not as efficient at absorbing oxygen when it is under strain. This makes it hard to use the oxygen you're breathing in, so it feels like you aren't taking in enough air. This is why when you return to exercise after time off, it feels like you're back to square one, panting desperately to catch your breath.

By getting enough exercise, you maintain your body's ability to effectively and efficiently get oxygen from the lungs to your heart when you are exerting effort. This isn't just important for making sure you aren't embarrassingly out of breath when you walk up the stairs in public. The process of getting oxygen from the lungs to your heart also determines how much oxygen makes it to your brain and other vital organs. This is why you may get light-headed if you can't catch your breath. We can all agree that getting enough oxygen to the brain is important, right?


Your metabolism slows down

Your metabolism may be great right now, but metabolism naturally slows for everyone as we age. One great way to offset these changes in metabolism is to get more exercise, including both cardiovascular and resistance training, like lifting weights. Research has shown that exercise helps increase a person's Resting Metabolic Rate (RMR), which is the rate at which your metabolism functions when you are not exercising or otherwise active. While RMR is affected by other factors as well, including a person's body weight and muscle mass, increases in RMR from regular exercise are valuable.


On the other hand, when you don't get enough exercise, your under-used muscles gradually shrink (thanks to a phenomenon called sarcopenia that causes muscle loss as we age) and your body fat percentage increases, further slowing your metabolism. Why does RMR matter? Think of it this way. As we get older and our RMR decreases, we burn fewer calories every day if we don't do something to increase the calorie burn, like exercise. This means that even though your habits stay exactly the same, you could start gaining weight. By getting enough exercise now and increasing your RMR, you can be proactive about your metabolism rather than reactive in the years down the road.

You could get injured

I've told clients before that they should think of exercise and fitness as a use it or lose it situation. The more you use your body, the more accustomed it is to movement and the more it can deal with before it becomes fatigued. When you don't exercise, though, your muscles become deconditioned. What this means is that when you are sedentary, the result is a partial or complete reversal of any prior gains in strength, cardiovascular fitness, and flexibility or mobility.

One consequence of these losses in physical fitness can be injury. Have you ever sprinted for the bus after weeks of inactivity only to strain a muscle? That's deconditioning at work. Or maybe you've tried to pick up something heavy (that you used to be able to lift without any problem) and threw your back out or strained your neck. You guessed it, deconditioning. In order to keep your body moving the way it was designed and injury-free, getting enough exercise is key. Maybe you didn't get injured, but are you starting to have more aches and pains? Deconditioning has also been associated with chronic low back pain. So if you're starting to notice a few more aches and a bit more stiffness when you wake up in the morning, it may be time to use it or lose it.

You get grumpy and depressed

If you haven't been exercising enough and you notice you're feeling grumpier or sadder than usual, it isn't all in your head. When it comes to your mood, regular exercise can be a huge factor. For those individuals with clinically diagnosed depression, exercise can lead to a reduction in symptoms. The benefits of exercise are not significantly different (better or worse) from those garnered from cognitive therapy or antidepressants and has been suggested as an adjunct to these types of treatment. You don't need a diagnosed mental illness to reap the benefits of exercise on mood though. Research has shown that people with non-clinical levels of depression and anxiety also benefit from regular exercise.

Those who exercise regularly and then stop or significantly decrease their exercise also see a difference in mood. Have you ever met someone who is training for a marathon and then gets very sad or grumpy when it comes time to taper? Some scientists argue that this is because exercise has an effect on neurotransmitters like serotonin and dopamine levels in the brain, which can help make us feel happy. For people who exercise a lot and then stop, it can almost be like going through withdrawal from a drug. A positive mood is quite a powerful thing. It's also important to note that as long as you're exercising regularly, it doesn't much matter exactly what you're doing. Research has found that improvements in mood and general well-being persist with regular exercise, regardless of whether the exercise was high intensity or low intensity. This means that you don't have to start running marathons or going to CrossFit to see an improvement in mood, you just need to move.


Read More