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.

To reach 20% body fat, Luke needed to lose approximately 20 pounds of pure fat.

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.

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.