Gaining Weight When Strength Training

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Have you noticed that your weight is going up while you increase your strength training workouts? That number on the scale simply means you weigh more or you weigh less. It is not a readout on the intensity of your workouts, your body composition, or your level of fitness.


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Key Reasons for Weight Gain

There are several different reasons that you may notice an increase in weight when you begin strength training. In some cases, the higher number means that you are making progress.

Increased Muscle Mass

Weight training can cause weight gain due to an increase in muscle mass. If you strength train regularly and improve your fitness level, your weight on the scale may increase while your body fat percentage decreases. Muscle is denser than fat and takes up more space.

This switch in body composition happens over months. You can confirm that it is happening by looking in the mirror at the changes in your body, trying on that pair of jeans you have owned since before you started your weight training program, or using a simple body fat percentage calculator.

If your body fat percentage shows more muscle and less fat, then that is the change you are looking for. If your jeans are baggy or loose, or if you look in the mirror and a more muscular person is staring back at you, then your strength training efforts could be causing a bit of an uptick on the scale. Breathe easy, you are making positive changes in your health, body definition, and physical appearance.

Water Weight

Water can change your weight. Ever notice you weigh less after a sweaty workout session? That loss of sweat can cause a decrease on the scale, just as a salty dinner can cause your weight to increase because your body is retaining water. Your weight can fluctuate due to your water retention versus water loss, and it is not related to your strength training at all. No matter what, stay hydrated all day.


Stress can cause weight gain. When you are under stress from tough workouts or a tough day at the office your body produces the stress hormone cortisol. More cortisol released in the body can cause fluid retention.

Lack of sleep due to stress can make you hungrier too, and you may eat more than you normally do. Make sure you plan some downtime to do the things that recharge you mentally and physically to alleviate some stress. Be sure to take a recovery day during your workout week, so you are not over-exerting your body.


A change in your diet may affect the number on the scale. Do not use workouts as your green light to eat whatever you want. Sometimes when you have an intense sweat session or you push yourself in a new way, you can look to food as a reward for a hard workout completed.

Your body does need fuel (especially when you train), but an intense workout is not a license to eat whatever and as much as you want. Eat clean and watch your portions—even when you are working out hard.

Other Factors

There are many factors that can change your weight such as hormones, stress, sodium intake, water consumption, and your body getting too accustomed to the same old workout. These variables can make your weight can go up and down. Keep making healthy decisions and use tools other than your scale to track your progress such as using a tape measure to track your chest, waist, hip, and leg circumference.

Weight Loss Benefits of Strength Training

Think of strength training as your long-term solution to weight loss instead of fearing that it will cause weight gain. Strength training offers many health benefits, including an increase in the number of calories burned. The more muscle you have in your body, the more calories you burn through every single day. So strength training is the best way to gain muscle mass and lose body fat.

“Muscle tissue burns more calories than fat tissue, and building muscles costs a lot of energy. As you increase the amount of muscle you have, you will also increase your resting metabolic rate.” —American Council on Exercise

A Word From Verywell

If you gain a little bit as you invest in regular strength training, do not panic. You are training your body to be a calorie-burning machine. Check your body composition or take a good look in your full-length mirror. You will see that your body is changing for the better.

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1 Source
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Council on Exercise. Trimming Off the Fat. Published January 29, 2009.

Additional Reading
  • Fit Facts: Trimming Off the Fat. American Council on Exercise.