Why You're Gaining Weight While Working Out and Eating Well

You've been exercising on the reg (you go, Glen Coco), only to step on the scale and find out that you've gained a few pounds. Your immediate thoughts: "why am I gaining weight?" and "how am I gaining weight for that matter?" While it can be easy to let a higher number on the scale screw with your head (especially if you feel you've been doing all the "right" things), gaining weight after working out shouldn't be a cause for panic.

Here, four reasons you might end up gaining weight while working out and eating healthy.

Water Retention After Exercise

Think you just lost a few pounds from that serious spin class? It's likely just water loss due to sweat. And if you're seeing a higher number on the scale, that could be due to water retention (which sometimes happens after exercise). The takeaway: The amount of H20 in your system has a heavy influence on your weight and could be the answer to the question, "why do I gain weight so easily?"

"Water makes up approximately 65 to 90 percent of a person's weight, and variation in water content of the human body can move the scale by ten pounds or more from day to day," says Jeffrey A. Dolgan, a clinical exercise physiologist at Canyon Ranch in Miami Beach, Florida. This is one of the main reasons diuretics are so popular — they flush the water out of your system, resulting in only a short term weight loss — but they don't change your body composition in any way. (

Weight Gain Immediately After a Workout

So, you're working out but still gaining weight? Have you ever noticed that right after (or even a day or two after) an intense workout the scale goes up? That's normal, and it doesn't necessarily mean you're actually gaining weight, says Dolgan.

"A person's scale mass is a combination of muscle, fat, bone, the brain and neural tract, connective tissue, blood, lymph, intestinal gas, urine, and the air that we carry in our lungs," he says. "Immediately after a workout routine, the percentage of mass in each of these categories can shift as much as 15 percent." Intense workouts cause variability on the scale due to factors such as hydration status, inflammation from muscle damage repair (aka delayed onset muscle soreness), even the amount of intestinal by-products or urine and blood volume, says Dolgan. So there you have it: if you're gaining weight while working out and eating healthy, it's probably not the type of weight gain that you think it is.

Gaining Weight Working Out from Strength Training

"A common comment when looking at the scale is that 'muscle is heavier than fat,' which is misleading," says Dolgan. "A pound of fat weighs the same as a pound of muscle; however, the volume of muscle is denser than the volume of fat and therefore, heavier."

If you start to change your body composition with your workouts — by building more dense muscle mass and decreasing your body fat — your scale weight may increase, while your body fat percentage may decrease. These changes happen over weeks and months (not hours or days) so the scale is useless when tracking them, says Dolgan. With all that in mind, gaining weight when exercising is to be expected. (Scared that strength training will make you bigger? Here's exactly why lifting weights won't make you bulky.)

Weight Gain from Muscle Vs. Fat

As noted above, the scale can't tell you how much of your body weight is muscle versus fat, which means if your goal is to improve your fitness level, it's not the best tool for measuring improvements. Not to mention, constantly checking the number on the scale when weight loss isn't necessarily your goal can result in too much time spent wondering, "why am I gaining weight?" or "why do I keep gaining weight?" And who really wants to think about poundage all the time? (

"If someone is trying to improve their fitness, they should ignore the scale and pay more attention to objective measurement tools such as body composition to track their progress," says Dolgan.

While weighing yourself can be one way to track your progress, it shouldn't be the only way. And it certainly isn't worth obsessing over with daily weigh-ins (and, as a result, fretting about gaining weight while working out and eating healthy). Don't forget, says Dolgan, losing pounds on the scale does not mean that you are more fit — it just means you are lighter, which doesn't mean much at all. And keep in mind that if you're exercising but gaining weight, it could be that your workouts are effective, but you need to alter your diet if you're after weight loss results.