For about two months I have been working out pretty heavily. I do intense cardio work five times a week for an hour to an hour and a half. I also weight train three to four times a week for about an hour. I saw a significant weight loss in the beginning, but now I just seem to stagger at the same weight. My sister told me that muscle weighs four times more than fat. How long does it take to gain muscle weight like that? I would think that it would take a month before I would gain that much from muscle, but I can't think of any other reason of why I am not losing weight anymore. Also, how long does it take for the calories to come off after you exercise?

You, my friend, have hit the proverbial plateau. This often happens after you've been working out for a few months. You were making significant, steady gains for a while, and then bam! your progress screeched to a halt. One of the main reasons this happens is that your body has in effect grown accustomed to the exercise you're doing and sees no reason to further adapt.

One way to get rid of the weight-loss blues is to change your workout. For instance, if you've been doing slow, steady jogs every day, try one or two interval training sessions a week. That's where you do a brief warm-up, then alternate periods of fast running with slow jogging or walking. A sample interval routine includes a five-minute warm-up at an easy pace, two minutes at a challenging pace, and one minute at an easy recovery pace. Repeat these 2-minute, 1-minute cycles 5-8 times and finish up with an easy cool-down and a stretch.

Another good rut buster is circuit training. It involves moving through your weight-training routine rather quickly, with only enough time in between exercises to move to the next one. A 20-minute circuit-training routine can burn more than 400 calories.

Besides changing your workout routine, look at your diet. Make sure your calorie intake hasn't crept up in the past few weeks. (It's tempting to give yourself an edible reward for a workout well done.) Keep a food diary to help you identify eating patterns. In fact, keep a diary of your activity, too, at least for a couple of weeks. That will help you figure out the things you need to change in order to keep losing weight and improving your fitness level.

As for your question about muscle weighing more than fat, that's not as much as a "pound of nails vs. a pound of feathers" as it sounds. Muscle is a denser tissue and thus takes up less room than an equal weight of fat. That's why it's possible to lose inches but show no changes in scale weight. Having more muscle means you have a more desirable body composition, or fat-to-muscle ratio. You may still weigh the same, but your body will look different, smaller, better and tighter. Though it may take you a few weeks to see measurable changes, you begin to put on muscle and burn calories from the moment you start exercising.

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