Many people begin running programs in order to lose weight and increase cardiovascular endurance. However, many of those people find that when beginning this new exercise regimen, rather than seeing the numbers drop on the scale, they actually weigh more. This seems counterintuitive, but there are several plausible explanations for the weight gain and they are not necessarily bad and it is not abnormal.

In normal populations, weight gain when beginning a new exercise program is normal and is good—your body is functioning as it should. Due to the physiology of muscle, weight gains will not be more than a few pounds, or only a couple of kilograms, over the first few weeks. After this initial period, weight loss will be observed.

Running is a challenging and rewarding activity, but there are many considerations before beginning a new program. As always, before beginning a new exercise program, check with your doctor for any contraindications. For those that are extremely overweight, starting a weight loss program through a running program may not be the best choice because of the joint mechanics and impact forces through the feet, ankles, knees, hips, and lumbar spine. For those mildly to moderately overweight and those wanting to try a new training program, running can be a great way to jumpstart a weight loss program.


Check out Shona Thomson’s Run To Lose Weight program for beginners

Running and gaining weight? Here's why

For the reasons of muscle mass gains and increased caloric consumption, due to assuming exercise, beginning a running program solely for weight loss may not be the best idea. Simply stated, weight loss is achieved by creating an imbalance between calories consumed versus calories expended.

Gains in muscle mass

The first possibility in noticing a weight gain soon after beginning a running program is gains in muscle mass, specifically in the lower limbs. It is true that lean muscle weighs more than fat and so increases in lean mass will cause that number on the scale to increase. That is no cause for concern, more muscle mass means more calories burned each day, which translates into a lower body fat percentage. Rather than being concerned with total body weight, a runner should be concerned with body composition. If gains in muscle mass are made and weight increases, this is not bad. This increase in weight will not cause clothing to fit poorly or pose any other problems.

In order to be efficient, in response to the needs of the exercise, the body builds muscle. No worries here, muscle mass is healthy and has many physiological benefits. If weight gain is due to muscle mass, then body fat percentage has decreased and you are more toned.

However, muscle mass gains are relatively slow, even in the most genetically gifted elite athletes. The increase in weight, in addition to muscle mass is the increase in glycogen storage in the muscle due to the increased metabolic needs of the exercising muscles.

Observations in nutrition

There is a caveat, though, to beginning a running program. Exercise burns calories, and your body hates to expend any more energy than it has to expend. Without realizing it, your body, through hormonal changes, could be causing you to consume more calories to account for this deficit through exercise. This is both good and bad.

-The Good

If you find yourself hungrier after beginning a running program, this is okay. Rather than turning to snack foods or larger servings at meals, consciously make yourself aware of food choices. Choose healthy foods containing carbohydrates and proteins and lower oils and fats. Choose to drink more water.

-The Bad

If you have increased your caloric intake based on your running and your weight has increased due to overeating, do not fear, it is not too late. Choose healthy foods rather than mindless eating and possibly increase your training volume without increasing caloric intake.


Running can be a great way to exercise, but if the desire is solely weight loss and fat loss, then running may not be the best form of exercise. Choosing healthy foods over common snack foods is key to weight loss. Seeing the number on the scale increase after beginning a training program is not necessarily bad, and within a few more weeks, the number will start to decrease.

WatchFit Experts change lives!

And they can do the same for you.


Pollyanna Hale Health and Lifestyle coaches
Lost 13 Kg in Total
Mel, 32y Location: London, United Kingdom Working with Pollyanna changed everything. I lost 13kg, got toned and have more energy than ever! Get same results!


Chriz Zaremba Fitness Consultant
Lost 45 Kg in Total
Chris, 50y Location: London, United Kingdom Lost 45kg after the age of 50 and now competes and wins physique competitions and runs marathons Check our weight loss plans