[bhujiko]

I've been told that muscles weigh more than fat and that's why you gain weight if you exercise, etc.

But I've just started running for a week, and I don't think that was really enough time for any real changes to take place... and yet I've gained a couple pounds. Have I subconsciously been eating more to reward myself for actually running? What do you think and any other advice?

[Ruthxxx]

You gain weight in your muscles due to water retention after strenuous workouts. However, muscle does NOT weigh more than fat. A pound is a pound. Muscle is more dense than fat so takes up less space per pound. Therefore you will look smaller when replacing fat with muscle although the scale may show the same or even a gain.
Rely on measurements if a gain on the scale bothers you.

[sidhe]

Probably what's happening is that your muscles are swollen from the new activity. It'll drop once your muscles repair themselves and get used to it.

It actually takes your body longer to make a pound of muscle than it does to burn a pound of fat. Keep in mind that a pound of anything weighs just that--a pound. So swapping out a pound of fat with a pound of muscle means you'll still weigh the same. But you'll be smaller, because muscle takes up less room.

[Meg]

Hi Bhujiko and welcome to 3FC! Congratulations on starting your running program!

There are some common fallacies that get tossed around about muscle building that aren't true but they sure can be confusing. If you don't mind, let me take a stab at some:

1. Muscle doesn't weigh more than fat. If you gain a pound of muscle, your scale will go up a pound, but only a pound. If you gain a pound of fat, your scale will likewise go up a pound. When people say muscle weighs more than fat, they're trying to say is that muscle is smaller than fat, so a pound of fat takes up less space than a pound of muscle (yay!) But it's not an explanation for the scale going up.

2. Running isn't muscle building exercise, so you haven't gained muscle from starting a running program. Running is cardiovascular exercise -- it burns calories, and can strengthen muscles and build endurance -- all fantastic! But to add muscle, you need to be working your muscles against resistance, which is weight training/resistance training, not cardio.

3. Muscle doesn't replace fat. They're completely different parts of your body. You can lose fat, you can lose muscle, you can gain fat and/or muscle -- but muscle gain and fat loss are independent of each other.

4. It takes many months of serious weight training and a good nutrition program in order for a woman to gain a few pounds of muscle. It's not easy and you're right, it could never happen in a week.

So what happened to you? It's very, very common to see the scale go up when an exercise program is started. Usually it's because sore muscles retain water and what you see is a temporary water weight gain on the scale, which is nothing to worry about! Sometimes it can also be us eating more to compensate for exercise, so you might want to track your calories closely and see if this is happening to you.

Here's an article you might want to check out: Working Out — And Gaining Weight?

Bottom line: unless you've been eating a lot more calories, what you're seeing on the scale is most likely a temporary water weight blip. Hang in there -- you're doing great!

[Lizzie2010]

People are saying muscle weighs more than fat, no it doesn't, back and forth. The truth is that muscle is denser than fat, so if you have equal volumes of fat and muscle... The muscle weighs more than the fat.

If you just started running, yes, you're probably retaining water... Esp. in your muscles where there's inflammation from normal damage from new exercising. However, many runners also gain weight because they eat a lot more. For some reason, running tends to make people hungrier. This certainly happens to me. If you don't give into your cravings for the first week or two, the hunger subsides typically. I try to combat this by writing down everything I eat, making a plan and sticking with it is really important when distance running.