Yes and no. I'm sure you've heard the calories-in-calories-out thing, and its a little more complex than that. Before I continue, any large weight-loss is best done with a doctor's guidance.

I want to start by saying most people have tried dieting/exercising and found they lost a few pounds, stopped losing weight, then regained it and got discouraged. This happens a lot. Let's look over a few details: When one starts dieting, they'll quickly see a lower number on the scale simply because less mass is in their digestive tract. Exercise (depending on the activity) can see a gain in muscle mass or blood volume. People usually underestimate their caloric intake and over estimate their expenditure.

This cycle is really common. In some cases the regimen was working and they got discouraged by a scale. In other cases, the regimen simply put them and their normal maintenance calories because they were over-budget before starting.

The solution to this conundrum is simple: stick with it. If your progress halts, cut some more calories from your diet and proceed. Don't worry too much about the scale, focus more on how you feel. Monitor that your activity level doesn't decrease and calorie intake doesn't increase.

Something really very helpful is to write down each caloric value before you eat. Every single thing, even the 5 calories of oil in a cup of black coffee. Add it up and keep track each day.