When you are in the process of training, you are helping your body to make many positive and healthy changes. When you stop working out regularly, which experts refer to as “detraining,” there are significant consequences—and these are not just the visible consequences of watching your muscles soften and your gut grow. These effects can happen quickly, and it is important to know what to expect.

1. Your Blood Pressure Increases.

Almost right away, your blood pressure will rise when you stop exercising. This effect is almost instantaneous. Your blood vessels will quickly adapt to your sedentary habits, and this happens within the first two weeks. When this happens, your blood vessels stiffen and your blood pressure will be where it was before you started working out regularly. Fortunately, this process can be reversible, and all you have to do is start working out again! After a week or so, you will start to see some positive changes once again.

2. Your Blood Sugar Levels Increase.

Under typical conditions, your blood sugar levels will rise right after you eat, in order to give your muscles and body tissues the energy that they need to do their jobs. After a mere 5 days of inactivity, your blood sugar will rise after you eat and remain high, instead of regulating quickly, like it does when you exercise regularly. Get this effect reversed by starting to exercise regularly again—it will only take you about a week to get your blood sugar regulated again if you workout regularly and eat better.

3. You Can’t Catch Your Breath as Quickly.

When you workout regularly, you tend to have great stamina and endurance, and don’t get winded very quickly. When you stop working out, you will find that you quickly get winded and you lose fitness quickly. Your VO2 max, which is a common measurement of fitness to determine how much oxygen is available for your muscles to use, will decrease quickly when you stop being active. This happens because when you stop working out, you will lose mitochondria in your cells. Mitochondria are the parts of the cells that convert oxygen into energy and keep your body running. This process is also reversible, but it takes a while to get it back once you lose it.

4. You Lose Muscle Mass.

While you can remain strong for a while after you stop training, you will find that you lose your endurance more quickly. This is partially related to the loss of muscle mass that begins to occur fairly quickly after you stop working out. Within two weeks of becoming sedentary, you can lose a significant amount of muscle mass because the fibres will begin to change from fast-twitching type IIa to the faster-fatiguing type IIx. As a result, your body will be less able to workout with high intensity for any length of time. Reverse this process by getting back to the gym and ensuring that you are getting enough strength training to build and retain the muscle mass that you have acquired.

5. You Gain Weight.

After only about a week of becoming sedentary, your metabolism will begin to slow down considerably. Unless you are eating far fewer calories than you were while working out, you will quickly gain weight. Your fat mass will increase quickly when you stop working out and begin to lose muscle mass. This may not result in an increase on the scale, but you will notice a difference in how your clothes fit and your appearance. Reverse this by getting physical again and, even if you can’t workout every day, make sure you get some activity a couple of times per week.

6. Your Mood Changes.

When you stop working out regularly, you will find it more difficult to regulate your mood. Many people begin to experience increased irritability, mood swings, increased anxiety and increased depression when they stop getting regular physical activity. In addition, it is suspected that your brain actually stops producing new brain cells and begin to suffer cognitive decline. Again, this process is reversible, and all you have to do is increase your level of activity.

Just about everyone knows that regular physical activity is good for your health, in many ways. Don’t worry too much if you fall out of the habit, because you can reverse the negative effects of becoming sedentary, just by becoming active again!