Taking a little time off from weight training won’t sink your entire workout routine, and trainers even say a day’s break can do you good. What happens exactly to your body when you start skipping the gym and stop lifting weights, and how fast does it happen? It all depends on the type of training you’re doing. Those training for cardio strength typically keep up their strength even when they take time off. Weight trainers are the ones who lose the greatest amount of strength over time.

The speed at which you lose muscle mass depends on a variety of factors, such as fitness level, gender and age. Many people see a loss of muscle definition within 3 weeks to 4 weeks. Metabolism starts to slow down around week five.

Here’s a timeline of what you can expect.

3 days: Your body will start to make changes internally, but you probably won’t notice. You won’t gain fat if you don’t make drastic changes to your diet.

10 days: You start to lose muscle tone as the physiological pathways that lead to muscle atrophy begin.

2 weeks:  You won’t lose strength, but you will begin to lose muscle mass. You won’t see any changes in body fat or body mass at this point. If you’re training HIIT, cardio, running for power, you won’t see any losses. If you’re training for strength, you will see losses. If the weights you’ve been using at the gym are in the 8-pound to 10-pound range, you won’t notice any difference when you pick them up again.

3 weeks: Go back to your workout at this point and you’ll see significant reduction in your performance during activities such as HIIT or sprinting.

4 weeks: You’ll notice you might be a little out of breath when you get back to the gym.

6 weeks: You’ll absolutely feel the effects when you go back to the gym again. You’ll feel more tired although you’ll still have strength depending on the type of your activity.

6 to 8 months: Now you’re going to see that you’re losing a significant amount of strength. Move that were once easy will feel extra challenging, and weights are going to feel heavier.

Even after an 8-month break, you can regain strength. One study looked at a group of women who took a rest of 32 weeks after following a 20-week training program. Although they lost much of the extra strength they had found in training, they gained strength back after six weeks of retraining. Some trainers say it takes about 21 days to get back in the groove.

Muscle memory will help you hold on to improvements even after a break of two years or more. If you start training again, you will build strength quickly. Muscle memory lingers long after muscles have atrophied. Muscles can hold onto up to a 15 percent higher force than before you started a training program.

Read more: What Happens When You Stop Lifting Weights?