Gaining 15 pounds of muscle mass is a daunting challenge specially if you want to stay lean enough to display your six-pack abs. Typically, gaining mass requires eating more calories, which in turn can end up being stored as body fat.
Your individual metabolism is the best guide to how much you should increase your calories to achieve muscle gains, while keeping your abdominal muscles visible.
Minimize Fat Storage
Use nutrient timing to maximize clean bulk muscle-building, while minimizing fat storage. For example, consume most of your "clean," low-glycemic carbohydrates in the earlier part of the day, more specifically, stacked around your weight-training workout.
A diet plan for abs and muscle gain includes drinking a post-workout shake containing 50g of whey protein, 100g of high-glycemic carbs and 30g of healthy fats (flaxseed oil or medium-chain fats). The Academy of Nutrition and Dietetics recommends that people who strength train consume half of their calories from carbohydrates every day.
More Protein at Night
Limit carbohydrate intake in the evening, especially high-glycemic starches and sugars. Since carbohydrates are our body's primary, preferred source of fuel, we should not need many of them prior to going to bed.
Instead, focus on consuming lean proteins such as fish, chicken, pork or turkey and healthy fats such as avocado, olive oil or nuts. Take a protein shake with 1 or 2 tbsp. flaxseed oil immediately before going to bed to improve muscle recovery.
Full Body Workouts
Perform three full body workouts per week. Use compound movements that engage a large amount of muscle fibers, such as squats for the legs or bench press for the chest muscles. ACE Fitness recommends working to fatigue to create lean muscle mass.
One way to do this is by using the machines at the gym. A technique called "drop sets" is used by lifters whereby you perform as many reps as possible, "drop" the amount of weight and do as many reps as you are able until you can no longer move.
Another recommended technique involves doing your compound exercises followed immediately by a single-joint exercise —for example, a squat followed by a leg extension to isolate and tax the quads.
Cardio After Lifting
Do 10 to 30 minutes of low-intensity cardio immediately following your weight-training to ensure that fatty acids released for energy are burned rather than restored. Since you have burned most of your glycogen (muscle-stored carbohydrates) during your workout, your body will use primarily fat for energy.
Examples of low-intensity cardio are steady-state walking on the treadmill, riding the exercise bike or using the elliptical machine. This will help ensure that you keep your abs while gaining muscle mass.
Sleep for Recovery
Always get seven to eight hours of restful sleep per night. Our bodies do not grow muscle in the gym. Muscle is built while we are resting and sleeping. Moreover, important hormones for muscle growth and fat-burning are also produced while we sleep according to ACE Fitness. Irregular sleep patterns will quickly lead to over-training and failure to achieve your goals.