From Men's Health magazine article 5 Reasons You're Not Losing Weight:
1. You Eat Fat-Free Foods
2. You (Still) Don't Eat Breakfast
3. You're Following Bad Advice.
4. You're Eating Too Much Sugar
5. You Don't Lift Weights
"In a study at the University of Connecticut, we put overweight men on a 1,500-calorie-a-day diet, and divided them into three groups — one that didn't exercise, another that performed aerobic exercise 3 days a week, and a third that did both aerobic exercise and weight training. Each group lost almost the same amount of weight — about 21 pounds. But the lifters shed 5 more pounds of fat than those who didn't pump iron".
This is more evidence of strength training's positive role in fat loss. If one goes on a diet with significant caloric restriction the body's response of self preservation is accomplished by lowering it basal metabolic rate. The body does this by catabolizing lean body mass. The weight loss will be both fat and muscle. If one strength trains the body receives the message that lean body tissue is vital to survive the demands placed on it. Rather than losing lean body mass the body preserves it and adds to it.