Cassandra Forsythe-Pribanic, Ph.D., R.D., and co-author of "The New Rules of Lifting for Women"

That's Fit: Can you explain why "inefficiency" in exercising may help you achieve a leaner body?

Cassandra Forsythe-Pribanic: Think about it in the way gasoline fuels your car: If your car is really efficient, you can go farther on less gas (which is what most of us want for our cars), but if it's inefficient, you burn more fuel faster. In the case of your body, when it's "inefficient," when you start running out of fuel (i.e., food energy), your body will need to tap into other resources to help it perform. This sometimes will be your fat stores because they are the most energy-dense fuel in your body. However, you have to eat fat to help your body burn fat, otherwise it will use other sources in your body such as glycogen (stored carbohydrate) or muscle protein (not desirable when that's what you're trying to maintain or increase). So, try to avoid eating a fat-free, or ultra-low fat diet or your body won't be able to burn the fat within you that you're trying to get rid of.

That's Fit: Rule #14 from your book says: "To reach your goals, you may need to eat more." Can you explain?

Forsythe-Pribanic: Most women under-eat because they don't understand how many good calories (i.e., non-junk food calories) their bodies really need each day to maintain their metabolic rates and activity levels. When they do this, the body has to compensate. It does so by slowing down "non-essential" activities in the body -- such as reproductive function, muscle-building and even thermogenesis. This means a woman can lose her period, always feel sore after a workout and constantly feel cold -- even on a hot day. For women who want to have a great weight-lifting session and not feel horrible for days after, they must eat more good food (high quality proteins, fats and carbohydrates) rather than less. This ultimately will lead to the body they're looking to achieve.

That's Fit: What's a great pre-workout meal/snack?

Forsythe-Pribanic: About an hour and a half before I lift, I like to have a mix of protein, fats and carbs. For example, this morning before I hit the gym, I had a half a cup of fresh strawberries, three-fourths of a cup of scrambled egg whites with one Omega-3 egg, and a slice of Ezekiel bread with two teaspoons of coconut oil. This helps keep my energy levels high throughout my entire workout.