First off, before we even start in on this one, let's clarify: a pound is a pound is a pound. A pound of muscle, a pound of fat, or a pound of feathers - they all weigh the same. The question here is, if you strength train consistently in an effort to lose weight you are likely to gain weight instead.
The difference isn't in weight, it is in volume. Fat takes up more space. Muscle is much more dense. If you were to take a 6 x 6 cube of fat and weigh it in comparison to a 6 x 6 cube of muscle, the muscle cube would weigh more. This is because it is more compact. You probably wouldn't notice a three pound muscle loss. However, a three pound fat loss could include your whole muffin top!
It's important to be clear with your goals. If you want to weigh less, it doesn't matter if you're losing fat mass or muscle mass. SO take your pick of the many delightful fad diets. They will all help you lose "weight." More than likely, however, you want to lose fat. The best way to lose fat is to gain muscle because muscle burns almost ten times more calories at rest than fat does. This is why people who tend to carry a lot of muscle tend to be leaner. It's a full body effect. Muscle and fat are inversely related. The more muscle you build, the less fat you'll have. So don't be afraid to put on a couple pounds of muscle. If your weight loss plan includes a sound strength training program, this is inevitable. Wouldn't you rather weight 150 pounds and be 15% body fat than weigh 130 pounds and be 30 % body fat? Muscle may technically weigh more, but it will also help you preserve your shape after you lose weight. It can help you maintain your feminine curves without the jiggle so you can fit into your favorite pair of jeans even after you've dropped some pounds. You can also create a tighter appearance of loose skin generated from fat loss by stretching it out over muscle mass. No one's saying put on a hundred pounds of muscle, but a little goes a long way.
In general, the whole world would do better to just throw out the scales and stop weighing themselves so obsessively. Do you want to look good or weigh less? No one can tell how much you weigh by looking at you, especially if it's mostly muscle. Your goal should be to favorably alter your muscle to fat ratio. If you have more muscle than fat you will surely be leaner.
