If a person relies on cardio alone for fat loss, only 50% to 75% of the weight they lose typically comes from fat, as their body taps into muscle for energy.

Research from Dr. Eric Helms indicates that the optimal rate for fat loss while preserving muscle is about 0.5% to 1% of body weight per week.

If Luke and Nicole lose muscle on their plan, it will take them longer to get abs because more of the weight lost will not be fat.

Vicki lost 5 pounds in a month from only dieting and training her abs, but only 2 pounds were fat, with the rest being muscle loss.

If a person is dieting, their body tends to compensate after cardio by burning fewer calories for the rest of the day, lowering non-exercise activity thermogenesis (NEAT).