Will Weight Training Make Me Gain Weight?

Are you one the many people who shy away from resistance training  because you mistakenly believe that it will make you gain weight gain or “bulk up?” Many regular exercisers focus on cardio-based activities and avoid the weight room altogether because of this belief and it’s really sad.  Despite what you may have heard or read, adhering to this belief could prevent you from reaching your health and fitness goals, and possibly result in long-term negative health consequences. In fact, resistance training can actually help prevent weight gain, improve body composition, and promote long-term health benefits. Here are some reasons, from St. Louis, Brentwood and Clayton, MO personal trainers, why incorporating resistance  training into your regular exercise routine is important for achieving your health-related goals.

Increased Caloric Expenditure

Increased caloric expenditure can result from resistance training both due to acute effects from training sessions and long-term effects from increased muscle mass. While a modest number of calories can be burned during a training session, the benefits extend past the workout. In fact, research has shown that caloric expenditure can remain elevated for several days following a workout. For example, one study found that a single resistance-training session resulted in a 5% increase in resting energy expenditure that remained elevated for up to 72 hours after the workout. Likewise, consistent resistance training has been found to increase resting metabolic rate by approximately 7% in both young and older adults. In addition to the post-workout benefits, increased muscle mass from resistance training boosts the metabolism as muscle mass requires more energy for tissue maintenance. Therefore, consistent resistance training can ultimately help you burn more calories throughout the day, thus assisting with your weight loss goals, even while you are at work or relaxing on the couch. 

Improved Body Composition

Body composition is the relative proportion of fat mass and fat-free mass (which consists of muscle, bone, organs, water and connective tissue). Physical inactivity, poor diet, aging and many chronic diseases can result in losses in muscle mass and bone along with gains in fat mass. Resistance training can halt or reverse these changes, leading to increased muscle mass, maintenance or improvements in bone mineral density, and losses in fat. Due to these alterations, tracking body-composition changes over time may be more meaningful than measuring body weight, as weight may remain stable as muscle mass increases and fat decreases. For example, researchers reported a 6.8 pound decrease in fat mass along with a 4.4 pound increase in fat-free mass with no change in body weight following a 26-week resistance-training program in older adults.

This research also demonstrates that you don’t need to be concerned about “bulking up.” Unless you are specifically training, eating, and supplementing with the purpose of maximizing muscle size and weight gain, you will not experience this effect. Instead, by altering your body composition through increased muscle and reduced body fat, resistance training can help you reshape your body, gain muscle definition and maintain a healthy weight.

Increased Strength

Consistent resistance training can significantly improve strength in both young and older adults. While even low-intensity muscular training can have positive effects, great strength improvements are experienced as training intensity increases. A loss in strength as we age is associated with functional declines, slower gait speed, increased fall risk, loss of independence, hospitalizations and poor quality of life. Because maximum strength peaks around the age of 30, and begins to decline around 50 years of age, resistance training is an essential part of a comprehensive fitness program at any age to preserve and enhance strength and physical function.

Improved Health Outcomes

In addition to weight, body composition and strength-related outcomes, resistance training can also have beneficial effects on many other health outcomes. Research has shown that resistance training can help prevent and treat many chronic diseases including cardiovascular disease, type 2 diabetes, and cancer. Furthermore, resistance training has been linked to positive mental health outcomes including improved cognition, self-esteem, fatigue, anxiety and depression.


Resistance training is an essential part of a comprehensive fitness program. Whether your goals are to improve weight or body composition, increase strength and function, or improve overall health, resistance training can help you get there. If you are new to resistance training, start slowly with lower resistance and gradually progress over time.  Or hire an ACE-certified personal trainer.

For more information on weight training and weight gain, contact Maurie Cofman, CMES, CES, TBMM-CES, Personal Trainer, Certified Medical Exercise Specialist, Health Coach and Corrective Exercise Specialist in the St. Louis, Brentwood, and Clayton, MO area.