Most of the time, when you start exercising, you’re supposed to lose or maintain weight -- not gain it. Some people use exercise as a way to build themselves up and gain weight, but seeing the scale numbers go up instead of down can be depressing if gaining wasn’t a goal. It can be especially frustrating if you’ve been doing a lot of cardio. But it is possible to end up gaining weight, for a number of reasons.
Cardio and Weight Loss
The constant movement of cardio or aerobic exercises like walking, running, swimming or jumping rope requires your body to use more fuel to sustain the energy needed to do the exercise. Assuming you are getting proper nutrition, your body will burn away stored calories. If you burn more calories than you’ve eaten that day, you’ll start burning excess calories that were stored as fat.
Unexpected Mundane Weight Gain
Sometimes unexpected weight gain isn’t so unexpected if you stop and look at what you’re doing. If you’re eating more because you think the cardio exercise will render the extra food as calorically unimportant, think again. You might have started eating too much, taking in more calories than you burn. The basic 3,500-calories-equals-a-pound formula remains the same no matter how much you exercise. Start tracking what you eat and how much exercise you’re doing, and add up the numbers. It could be that you’re just eating much more than you should.
One substance you need to increase when you exercise, even if you are trying to cut back in your diet, is water. If you don’t drink enough water and become dehydrated, you could actually start to retain water, causing a temporary weight gain. Think of it as your body hoarding what little it has. Clemson Cooperative Extension recommends drinking between 1/2 and 1 cup of fluid -- either water, milk, juice or a sports drink, though that is only if you are exercising for more than an hour -- every 15 minutes while exercising. Note that milk, juice and sports drinks add calories to your daily total. Clemson says you should also drink at least 2 to 3 cups of fluid before and after exercising to ensure your body has enough to work with. Water retention can also occur if you eat too much sodium. Hendrix College’s Health Services department says drinking more water should help get rid of the retained water, but be aware that overloading yourself with water can be harmful.
Weight gain can occur as the result of health problems like hypothyroidism and polycystic ovary syndrome. If you started your cardio exercise in response to sudden weight gain, it is possible that you have an underlying health issue, of which weight gain is a symptom. Hypothyroidism occurs when the thyroid gland in your neck doesn’t produce enough thyroid hormone; your metabolism slows down as a consequence. Women dealing with polycystic ovary syndrome have recurring ovarian cysts and produce extra male hormones called androgens. The cause is unknown, but weight gain is a symptom. Other medical reasons for weight gain include heart problems and Cushing syndrome, in which you have too much of the hormone cortisol. Only a doctor can test for these conditions.
If things have really gotten out of hand -- and you know you don’t have an underlying health problem -- please speak with your doctor, a dietitian and a certified fitness trainer. You might be at the point where it’s no longer a matter of just trying harder. Get professional medical and fitness advice that will set you off on the right track toward healthy weight loss.