Yes, sometimes people who exercise actually gain weight - and it's not muscle. I've seen it happen. Not just to others, but myself as well! Long before I began this very blog, and in fact, before I ever worked in the field of fitness, I was a borderline couch potato that considered it a "good week" if I made it to the gym to work out twice. My how things have changed.

My experience with weight gain and exercise came in 1998 when I decided to do the AIDS Ride from Minneapolis through Wisconsin to Chicago. I thought this would be a good way to get in shape, participate in a worthy cause and get to know people. Now, knowing I was signing up for a 500-mile bike ride...on a steel frame mountain bike that weighed more than my car...should have made me ask myself, "are you really ready for this?" But it didn't, and I've since learned a valuable lesson about impulse control.

How I Gained Weight (in 6 days) While Exercising All Day
The ride was quite well organized, with rest stations every 15 to 18 miles of the 500-mile journey. Each and every station was loaded with everything a person could need, from toilets to first aid to food. Lots and lots of food. Now the food was generally of the staple variety, including bagels, bananas and energy bars. I always made sure I grabbed a couple things to eat, and never forgot to fill my water bottle with the sports drink on-hand because apparently at that time I thought my body actually needed the extra 400 calories to muscle through to the next rest stop - about an hour away - only to repeat the process until I got to the final rest stop for the night. The final stop of the day was camp. Again, lots of fun and plenty of food. But since I was working so hard, I should eat a lot, right?

By the time we reached Chicago, I was a changed woman. The ride itself was indeed amazing. I met some people whom I will never forget. It was a great life experience, and I'm glad I did it. That said, when I finally made it home a couple days later, I was also physically changed - six pounds heavier. It had only been a week - and I rode 500 miles. How could this have happened?

It's likely part of the weight I gained was fluid, but the rest of it was weight I had to work off after I got home. Fast forward about 12 years and a healthy career in the fitness industry. The reason I gained the weight is more than apparent.

Eating and Exercise
A lot of people who exercise to maintain or even lose weight develop the exercise-to-eat mentality. If you're exercising significantly more on a regular basis, sure, you can indulge in greater portions or something you'd consider a treat every now and then. Indulging regularly, however, could keep you stuck in a weight loss rut, or even cause weight gain.

Here are three things to consider before you refuel for your next workout:

1) The 90-Minute Rule
Only after 90 minutes of continuous moderate to intense exercise should you replenish your energy needs. Most people who do this much continuous exercise are probably training for something. They may be out for a long run or bike ride. In that case, it's essential to refuel. On the other hand, if you're getting in a good 45-minute workout, there is no need for the energy bar or sports drink. Your liver does a great job storing about 90 minutes of all the sugar you'll need to boost you through a workout. Only after that does it start to run low.

2) Metabolism and Weight Loss
It's true that exercise, particularly strength training, boosts your metabolism. As you become fitter, you lose some fat and gain muscle. Your engine burns faster and yes, you can eat a little more. However, as that engine burns, it's also burning off the pounds...which is a good thing! That said, the less you weigh, the lower your metabolism. The lower your metabolism, the less you need to eat.

If you take two people, one is 150 pounds and one is 180 pound, and they both workout the same amount doing the same things, the 180 pound person needs to eat more to maintain that weight than the 150 pound person. Similarly, if you recently lost ten pounds, your caloric requirements are not what they were before you lost the weight. Now you need to eat less.

3) The 3-Hour Meal-to-Exercise Window
After you eat a meal, your body needs about three hours to break it down enough to 1) allow you to feel comfortable enough to work out and 2) allow the oxygen-rich blood that helped break down the food you ate to return to your extremities to help you workout better.

If you can't wait the full three hours after eating to workout, then eat less. It's also not a bad idea to try to eat foods that you know your body digests easily. Eating a big salad with lots of veggies, even if you wait the full three hours, can cause stomach discomfort, to say the least.