The #1 Reason for Gain Weight From Exercise & Healthy Eating

Have you started eating healthier and exercising more to lose weight, build muscle, improve your health or address some lab results? Yet when you step on the scale after weeks of putting in effort at the gym and in the kitchen, you might be shocked to see the number has gone up. Although this can feel defeating, it can actually be a positive sign. 

Below, we’ll reveal the number one reason why you might gain weight when working out and eating healthier, plus share a few other possibilities too. 

The #1 Reason Why You May Be Gaining Weight Despite Working Out & Eating Healthier

The number one reason you might gain weight while working out and eating healthier is because you’re gaining muscle mass. And that’s a good thing! 

When you begin to exercise, your body composition changes. Our bodies are made up of body fat and lean muscle mass. Body fat protects and insulates our internal organs, and serves as an energy reserve. A certain amount of body fat is physiologically essential, with females requiring a higher percentage than males to maintain healthy hormonal function and reproductive health.

Lean muscle mass is found in our muscles, tissues and bones. It helps maintain our body’s structure, keeping us upright, balanced and physically mobile. Having sufficient muscle mass is also vital to helping us live longer. 

A pound of muscle and a pound of fat will weigh the same, but look different. Muscle is dense and compact, while fat is larger in size and volume. So, when you build muscle and lose fat, the scale might not budge or increase, but you may also notice you can lift more bags of groceries at one time or notice more muscle definition in your limbs when looking in the mirror.

Muscle mass is also more metabolically active. This means muscle burns more calories even at rest. The more muscle you have, the more calories you burn in a typical day. Plus, as we age, we naturally lose muscle mass, making it even more crucial to maintain and build it up for overall health, bone health, strength, mobility and balance.

Additionally, starting a new workout routine or engaging in more exercise than you are used to, can cause temporary exercise-induced muscle damage. This leads to soreness, swelling and inflammation as your body works to repair itself. Edema or fluid retention and swelling in muscles can occur within 1 to 2 hours after exercise and peak around day 4 to 10. This inflammatory process can cause temporary weight gain.

Remember, these changes are temporary. While you may be upset with the number on the scale initially, gaining and maintaining muscle is beneficial for a longer, healthier and more active life.

Other Reasons You Might Gain Weight from Exercise & Healthy Eating 

While gaining muscle mass is often the reason for weight gain during a new health journey, there are a few other reasons you might be gaining weight too:  

• Drinking More Water: When you start breaking a sweat during workouts, you likely will start to feel a lot more thirsty. Increased intake of fluids, around and after workouts, can cause you to temporarily gain weight too. Two cups (or 16 ounces) of water—or another fluid—is equal to about one pound. If you drink a few cups after a sweaty gym session, you will likely see it reflected on the scale. For your most accurate weight, check it first thing in the morning after waking up. 
• Increasing Your Salt Intake: We lose fluid and electrolytes in sweat, which both need to be replenished post-workout. The most abundant electrolyte in sweat is sodium. Replenishing electrolytes through an electrolyte beverage or food sources, like adding more salt to your food or grabbing a handful of salted nuts, may cause your body to retain fluid. This temporary fluid retention helps keep you hydrated but also may lead to temporary weight gain. 
• Increased Appetite: Being more active often increases hunger. It’s important to have well-balanced meals and snacks ready, especially post-workout, to avoid overeating or making unhealthy food choices. A balanced meal should consist of complex carbs, proteins and fats to provide your body with nourishment and help you optimize and recover from your workouts. 

Remember, these changes are normal and healthy (and often temporary), so don’t let them derail your exercise routine or eating pattern. Drinking more water, increasing your salt intake and having a bigger appetite are common and other possible reasons why you may experience temporary weight gain. So if it causes you stress, ditch the scale and instead focus on how you feel and other non-scale victories like improved sleep, less stress, increased energy and better mood. Consistency and sustainability are key to achieving your long-term health goals. 

The Bottom Line

The number one reason you might gain weight while working out and eating healthier is often from gaining muscle mass. Keep in mind that this weight gain might be temporary as your body transitions to a healthier, stronger body composition. Other reasons you might be gaining weight from exercise and healthy eating are drinking more water, increasing your salt intake or heightened appetite. Building muscle supports overall health, improves strength, balance, bone health, mobility and longevity.