5 Reasons You’re Gaining Weight While Working Out

You’ve been putting in the effort and exercising regularly. But you’ve noticed something peculiar: When you step on the scale, the number goes up rather than down. What gives?

There are several reasons why you might be gaining weight while working out. The uptick can be frustrating if weight loss is one of your fitness goals. But it’s not usually cause for concern. And a few minor adjustments to your routine might keep weight gain at bay.

What causes weight gain from working out?

Several things can cause you to gain rather than lose weight when working out consistently.

1. Increased muscle mass

Exercising causes tiny tears in your muscle fibers. It sounds bad, but it’s actually a good thing. After your workout, your body works to repair these tears, allowing your muscles to get bigger and stronger.

So even though you may be losing fat, you’re gaining muscle. You might feel slimmer, even as the number on the scale rises.

“The scale doesn’t tell the entire story,” said exercise physiologist Christopher Mohr, PhD, RD. “Since muscle and fat take up different volume, they look very different on the body.”

But Mohr says your overall body composition, including body fat, is more important than your weight. It’s harder to measure your body fat, but some smart scales can give you a rough estimate. You can also get a body scan at a clinic for a more accurate number.

But none of these measures paints a complete picture of your health and fitness.

2. Post-workout inflammation

Those tiny tears in your muscles can also cause temporary post-workout inflammation. “This is expected and perfectly healthy,” Mohr said. You may retain fluid after exercise as your body repairs the damage, which can cause water weight gain. Any uptick on the scale is usually minor and temporary.

Weighing yourself regularly can be helpful on your weight-loss journey. Mohr suggests skipping a weigh-in right after your workout. But try to weigh yourself at the same time of day. “First thing in the morning, before exercising, eating or drinking anything keeps things on a level playing field,” Mohr said.

Cut back on checking your weight if you find yourself obsessing over the number on the scale.

3. Supplement use

You might think you need supplements to meet your fitness goals. So you put an extra scoop of protein powder in your morning smoothie or grab a pre-workout drink on your way to the gym.

But pre-workout supplements are not FDA approved, and ingredients vary by brand. Some might have more calories — many of them from added sugar — than you realize. Common supplement ingredients like creatine may also cause temporary water retention.

Most people don’t need pre-workout supplements because they can get plenty of performance-boosting nutrients from a balanced diet. Stick to whole foods unless you are an athlete with a rigorous training schedule or your doctor suggests supplements for a medical condition. It will be much easier to manage your diet and reach your body-composition goals.

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4. Workout plateau

Imagine exercising consistently for weeks and seeing a downward trend on the scale. Then your progress suddenly halts, even though your workout plan and diet haven’t changed. This is called a workout plateau. It occurs when your body adjusts to your exercise routine and no longer needs as much energy to support your effort. So you don’t burn as many calories as you did before.

“Plateaus are normal,” said Kevin Huffman, MD, a bariatric physician. “Your body adapts to what you’re doing, so the scale could stall for a week, a month, or even more.”

That doesn’t mean you should give up, but you may need to take on new challenges, such as increased exercise intensity or duration. “Change your workout, try some new moves, or tweak your diet just a little to make sure your body doesn’t get used to your routine,” Huffman said.

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5. Diet changes

Exercising regularly and eating balanced meals are critical lifestyle changes for healthy weight loss.

You can spend hours working out. But if you don’t adjust your diet, you may gain weight. Many weight-loss diets emphasize calorie restrictions that are harmful and hard to maintain. For example, a low-calorie diet can make you lose muscle instead of fat. And less muscle mass could make you regain any weight you lose.

Exercise can increase your appetite, so you might eat more than usual. Loading up on empty calories, from processed foods like energy bars, sugary cereals, and soda, can contribute to weight gain.

Finding the right nutrition plan to support your weight-loss goals can be tricky. You may need to lower your daily calorie intake. But you don’t have to track everything you eat, and you shouldn’t try overly restrictive diets. Consider healthy tips to get the calories you need, such as:

• Tracking how your workouts affect your appetite and mood

• Adding more lean protein, fruits and vegetables, and whole grains to your diet

• Reducing processed foods and sweets in your diet

• Using a meal planner to prioritize balanced, nutritious meals

When should you be worried about weight gain from working out?

Working out in and of itself doesn’t cause you to gain weight. Building lean muscle mass can add a bit to the scale, and that’s a good thing. If something else is causing you to gain weight, such as a change in your diet, overdoing it with supplements, or not challenging your body, you can easily readjust and get back on course.

But most experts will tell you to take your attention off the scale and notice other changes that indicate progress. “The most important factor is how you feel,” Huffman said. “Do you feel better? Are you stronger, more energetic? If so, these are great signs that you’re moving in the right direction.”

If you exercise regularly and make other lifestyle changes but keep gaining weight, talk to your doctor. They might provide additional tips or look at other factors blocking your progress. These could include underlying health conditions — such as hypothyroidism — or your medications.

But don’t give up. “Consistency and a whole-body approach to health are the real keys to success in the long run,” Huffman said.

Why trust our experts?

Written by:

Jody Braverman, CPT, RYT

Jody Braverman has worked in the health and fitness industry –– as a trainer, yoga teacher, nutrition and lifestyle coach, writer, and editor –– for more than two decades. She graduated with a B.A. from the University of Maryland and maintains several accredited certifications.

Edited by:

Lauren Savage, MA

Lauren Savage, MA, is a health editor at GoodRx, where she focuses on movement, exercise, and healthy aging. She aims to provide readers with the information they need to live healthier, more active lifestyles.

Reviewed by:

Karen Hovav, MD, FAAP

Karen Hovav, MD, FAAP, has more than 15 years of experience as an attending pediatrician in a variety of clinical settings. She has worked in a large academic center in an urban city, a small community hospital, a private practice, and an urgent care clinic.

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