Which is why I've spent a lot of time trying to lose my last 10 pounds of flab. Unfortunately, like many men, I've found that goal to be frustratingly elusive. That is, until I enlisted the help of Aragon, whose nutrition and training methods have shaped the bodies of NBA athletes, Olympians, and competitive bodybuilders.

Using Aragon's advice, I slashed my body fat in half—down to a lifetime low of 6.8 percent—and sculpted not only the muscles of my midsection, but the ones everywhere else, too. Now it's your turn. Use Aragon's simple 5-step diet plan to finally finish off your gut for good. (And for Aragon's complete cutting-edge guide to losing fat, check out the The Lean Muscle Diet, available everywhere books are sold.)

Calculate Your Calories

When it comes to calories, Aragon has a simple rule: Eat for your target body weight. Let's say you weigh 220 pounds but would like to tip the scales at 180. You'll adopt the calorie intake of a 180-pound man.

The formula: If you perform 1 hour or less of exercise a week, multiply your target body weight by 10. That's how many calories you should consume daily. However, if you work out more than that, add 1 to the multiplier for every additional hour you train. So if your target body weight is 180 pounds and you exercise for 3 hours a week, you'd multiply 180 by 12—giving you a target of 2,160 calories a day. You can divide those calories into however many meals you want—three, four, five, or six—as long as you don't eat beyond your daily limit.

Eat by the Numbers

Sure, you could just focus on calories. But by eating the right amounts of the right nutrients, you'll speed your results without feeling like you're on a diet.

Protein
You probably don't need to be sold on the virtues of protein, since it's the raw material for muscle growth. But it also helps extinguish your appetite and aids in fat loss.

The formula: Eat 1 gram for every pound of your target body weight. If you want to weigh 180 pounds, you'll eat 180 grams of protein. One gram of protein is about 4 calories. So to calculate the calories you'll be eating from protein, multiply the number of grams by 4. In this case, that's 720 calories.

Fat
For years, this nutrient was considered a dietary demon. However, recent studies clearly show that it's not fat that inflates your belly, but too many calories, period. And, it turns out, fat may actually keep you from overeating because it makes you feel full. The end result: You stop eating sooner and stay satisfied longer.

The formula: Eat half a gram for every pound of your target body weight. If your goal is to weigh 180 pounds, that'd be 90 grams. And since 1 gram of fat has about 9 calories, that's 810 calories from fat. This will be about 40 percent of your total calories.

Carbohydrates
Carb-containing foods not only taste good, but can also be rich in vitamins and minerals. So you don't need to eliminate them altogether; you just need to make sure you don't eat them in excess. And consuming the right amounts of protein and fat will make that goal far easier, since both keep hunger at bay. That's one key reason Aragon places a greater priority on protein and fat and leaves the remainder of your calories for carbs.

The formula: Add your calories from protein and fat, and subtract that total from your allotted daily calories. Using the 180-pound example, that leaves you with 630 calories. This is the amount of calories you can eat from carbs. As protein does, carbs provide about 4 calories per gram—so divide your carb calories by four to determine how many grams of carbs you can eat. In this case, it's about 158 grams.

Create Your Menu

Build your diet around whole foods—those you'd find in nature. You should choose mainly meat, eggs, dairy, fruits, vegetables, nuts, and legumes, plus grain products that are made with 100 percent whole-wheat flour. Note that typical junk foods—candy, baked goods, and sugary drinks—don't make the list.

Use the food options below as a guide for designing your diet. Mix and match the foods in any way you like while following the calorie, protein, fat, and carb guidelines for your target body weight. The nutrition numbers listed don't provide exact amounts of calories and other nutrients, but these ballpark averages allow you to eyeball your intake. 

Dial in Your Diet

Follow these rules to make your eating plan even more effective.

1. Consume at least 2 servings of vegetables a day. Vegetables are low in calories and high in belly-filling fiber.

2. Eat at least 2 servings of fruit a day. Fruit provides your muscles with plenty of carbs for energy, but has less impact on your blood sugar than grains and other high-starch foods do. This is important because it can help you avoid the cravings and binges that occur when your blood sugar rises quickly and then crashes. Ideally, the majority of your carbs will come from fruits and vegetables. So limit yourself to just two daily servings of grains, beans, and high-starch vegetables, and consume the rest of your carbs from produce.

3. On the days you work out, eat 1 hour before you exercise and again within 60 minutes after your last rep. For both meals, aim for 0.25 gram per pound of your target body weight in protein and carbs. So if your goal is to be 180 pounds, you'd eat 45 grams of each nutrient. This provides your muscles with a healthy dose of nutrients for fueling your workout and for upgrading your muscles after you're done. Keep in mind that your total protein and carb intake for the day doesn't change; you're just eating strategically for better results. Options are . . .

- A preformulated shake, that has a mix of protein and carbs. Add fruit if it requires more carbs.
- A shake that's almost entirely protein—such as Optimum Nutrition Whey—along with 1/2 cup of oatmeal and a piece of fruit.
- A tuna-salad or turkey sandwich.

Forget About the Details

One meal a week, go ahead and splurge. "There's always room for junk food, as long as it's a minority of your intake," says Aragon.

Editor's note: This article was updated on December 23, 2014. Since it was originally published, Alan Aragon has coauthored The Lean Muscle Diet with award-winning journalist Lou Schuler, and that is reflected in this story. The Lean Muscle Diet details how you can create a custom nutrition and exercise plan for your body. Whether you have 20, 30, 50 or more pounds to lose, or you just want to shed those last 10 pounds, or you're a skinny guy trying to pack on lean muscle, this book has a plan for you.