Remember the old adage that “abs are made in the kitchen?” Well, the same principle applies to your entire midsection. “You can do all the gym work in the world,” says Zach Even-Esh, founder of New Jersey’s The Underground Strength Gym, “but if your body’s covered by a layer of fat, then nobody will know.”

That’s why getting yourself on a very strict, clean diet—with the right balance of proteins, fats, and carbs—is the key to transforming your flabby torso into a perfectly cut, tapered midsection.

But how do you do it? The first order of business is to get your math in order, and that means calculating what your overall calorie intake needs to be, says sports nutritionist and strength coach C.J. Murphy, M.F.S., owner of Total Performance Sports, in Malden, MA.

So if pure fat loss is your goal, you need to set the goal of ingesting roughly 8 to 12 calories per pound of your entire bodyweight per training day, depending on how active you are and how much fat you need to shed. (And remember: Be honest with yourself.) If you’re already fairly lean and you just want better muscle definition, you’re allowed 12 to 15 calories per pound of body weight. (Though it’s best to start on the low end and see how it goes.) So if you’re a 200-lb guy looking to get lean, at 10 calories per pound, you’re looking at roughly a 2,000-calorie-per-day diet.

Now, what should it be? Well, Murphy recommends a simple high-protein carb-cycling program, with which you eat more carbohydrates on your strength training days and less on days off, creating a caloric deficit that torches fat.

So let’s start with strength-training days.

First, of course, you’ll need lots of lean protein. “That includes anything that swims, runs, or flies,” says Murphy. Meaning: steak, chicken, fish, turkey, and ground beef. Eggs and protein powders are good, too. As a rule of thumb, Murphy calculates meats at 7g of protein per ounce. “Different foods have different values, yes, but if you’re eating a wide variety of meats you’ll still be in the ballpark, which is what we want.” All told, that means roughly 1g of protein per pound of body weight (calculated at 4 calories per gram). So that same 200-lb guy needs to eat 200g of protein every gym day.

Then there are carbs: Yams, sweet potatoes, white rice, white potatoes, and fruit are all good carbs to power your workouts. Those carbs should make up 35-45% of your daily calories, calculated at 4 calories per gram. We’ll give our guy 220g.

The remainder of your calories each day can be made up of vegetables and healthy fats, like nuts, nut butters, olive oil, and avocado. (Calculate fats at 9 calories per gram.) For our guy, that comes to roughly 35g of fat. On non-strength-training days, you should cut carbs up to 50% and increase fat to 20-30% of total calories to help fill you up, reduce hunger pangs, and increase your likelihood of sticking to it. So our example guy should eat 200g of protein, 125g of carbs, and 50g of fat for a total of 1,750 calories. But when you eat is important, too.

“Earn your carbs,” says Murphy, which means you should be ingesting carbs directly pre- and post-workout. Also, save the bulk of your off-day carbs for the evening, which prevents you from bingeing at night and gives you a little more energy (in the form of stored glycogen) to carry into the next morning. “Carb cycling isn’t the only way to put on lean muscle mass, but it’s the simplest,” Murphy says. “It’s easy, people get it, and it’s hard to screw up.”

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