Why Am I So Tired After I Lift Weights?

If you've been exercising for a while, there's a good chance you know what it's like to feel tired after lifting weights. But if you find that you're always tired after weightlifting, it might be time to take a closer look at any lifestyle factors that may be contributing to your fatigue. That's because the more you demand of your body, the more you need to give back.

Feeling overly tired after exercise is a red flag that something more is going on. (Image: Westend61/Westend61/GettyImages)

Intense exercise sessions require your body to perform at its peak level. This means you need to give back through proper nutrition, hydration, rest and sleep habits. While some degree of fatigue is to be expected, feeling sleepy after lifting weights — especially on a regular basis — is cause for concern.


Lack of sleep, not eating enough before and after a workout, and being dehydrated can all cause you to feel tired after weightlifting.

Nutrition and Weight-Training Fatigue

Your diet is one of the first places to start when you're trying to figure out why you're so tired after weight training. The foods you use to fuel your body before and after a workout not only determine the intensity of your training sessions, but they also contribute to how quickly you recover when finished.

  • If you exercise later in the day, make sure to eat a meal that's high in carbohydrates, low in fat and contains a moderate amount of protein about two to three hours before working out.
  • About 30 minutes prior to weight training, eat a small, easily digestible snack with carbohydrates and protein.
  • If you lift weights in the morning before eating a full breakfast, make sure to eat a snack with carbohydrates, protein and a small amount of fat, such as peanut butter toast with a banana.
  • After any workout, you want to have a snack or meal within one hour of finishing. This is even more important if your workout is intense or particularly tough that day. This fuel can be a recovery drink or meal, or a snack with carbohydrates, protein and a healthy fat.

Hydration and Weight-Training Fatigue

Fatigue is one of the first signs of dehydration. So if you're tired after weightlifting, you need to review your fluid intake. Keeping track of how much water you drink (with a water bottle or tracking it in your phone) can help you get a better idea of your individual needs.

Hydration and fluids before, during and after activity all factor into your energy level. If you're experiencing fatigue after weightlifting, your intake of fluids may be off. The average male needs about 15.5 cups (3.7 liters) of fluid each day, and the average female needs about 11.5 cups (2.7 liters) of fluids each day.

Add on exercise and your fluid consumption needs to increase. Plus, if your workout is intense and lasts longer than one hour, you may want to consider a sports drink that contains electrolytes.

Rest and Weight Training Fatigue

The amount and quality of sleep you get each night factor into weight-training fatigue. According to the National Sleep Foundation, adults, ages 18 to 64, need seven to nine hours of sleep each night. While skipping out on an hour here and there won't cause you to crash and burn, regularly getting less than the recommended amount will eventually cause you to feel tired after weight training.

But it's not just sleep that you need to consider. The amount of rest you get between strength training sessions also plays a significant role in how you feel after working out. In general, resting muscle groups for at least 24 to 48 hours between training sessions gives you enough time to recover and repair for your next session.

That said, you also need to pay attention to how long you're lifting weights. Depending on the intensity of your resistance-training session, working hard for over an hour may cause you to feel more tired after weight training.

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