I'm sure you already know this but there is such a thing as healthy and unhealthy way of losing weight. We want to stay healthy, lose weight and get in the best shape of our lives - that's what daddy likes to hear; none of this starving ourselves to lose weight business. Just getting started with weight loss and have no clue what you're doing? We've all been there at some point (unless you've been blessed with a naturally lean body, in which case on behalf of the entire world I just want to say "we hate you") but before I go over the differences I always want to recommend getting a book by an established cat in the fitness field. You want something written by someone who is a credible source for information!
Okay so the healthy way of weight loss is a combination of cardio and dieting. You're eating healthy alternatives to what you were eating in the past, you log the calories you're eating every day - you do this about a week with no cardio. Once that week is up and you've developed a consistent diet plan (this is where top quality books come in) you analyze how many calories you need to burn to lose weight (burning more calories than you take in = how you lose weight). How many calories you need to burn will determine the intensity of your workout.
The unhealthy way is starving yourself to lose weight, continuing to eat junk food/fast food, not exercising at all, taking a diet pill or lifting weights. The last one may have you thinkin' so settle down tiger, I'll get to it. First, starving yourself to lose weight; not a good idea. Your body requires x amount of calories (depends on your weight/fitness level) to do every day movements; if you're not getting those calories you're going to feel a mad loss of energy and life won't feel too good.
Second, if you're going to continue eating junk/fast food you're not going to lose any weight, period. Instead of sweet tasting chocolate/candy grab a banana or two, maybe an orange; besides the obvious benefits (more potassium in the banana, more vitamin C in the orange) the have just as much sugar as the sweet foods you're currently eating. If you want fast food make tuna salad sandwiches; I love these and they take little to no effort/time to make. High in protein and low in carbs - it's a beautiful thing.
No exercising at all will guarantee no results; you're setting yourself up for failure. As I mentioned before weight loss happens when you burn more calories than you take it; that's the ticket. If you're not burning calories you either meeting the "requirement" that has made you overweight or you're adding more calories on top of that, in turn make you gain more weight.
Diet pills are a complete waste of money - don't even think about spending a dime on them. They recommend you exercise and eat right while using them which is going to make you lose fat, not some pill. You take the pill, exercise/diet, lose weight and you're automatically going to assume the pill did all the work - it wasn't the pill, it was YOU.
Now for the lifting weights part; a common misconception is that you can gain muscle and burn fat at the same time - wrong! You can only do one at a time, and you guessed it, you start with weight loss THEN add muscle if you desire. There's no point building muscle and THEN losing weight; you'll lose all the muscle mass you spent all your time gaining.