Pop quiz: What's the best way to get shredded? If you're like most people, what came to mind was a combination of extreme food and calorie restriction, grueling high-rep weightlifting workouts, and hours and hours of cardio each week.
Ironically, this is the worst way to go about it. 
This approach guarantees a downright miserable experience of horrible food cravings, rapid muscle and strength loss, and a building fatigue and lethargy that eventually burns you out.
It doesn't have to be this way! When you know how to use nutrition properly, you can rapidly lose fat while maintaining strength. 
You can also completely avoid daily struggles with hunger, cravings, and energy levels.
This isn't just something that works on paper, either. It's a reliable combination of strategies that I personally use to get to 6-7 percent body fat with relative ease, and which have been successfully used by thousands of people I've helped through my books and work at Muscle For Life.
I'm going to lay everything out for you. Let's get past the common myths and mistakes and discover how simple getting shredded can be once you put all the right pieces together!

IT ALL BEGINS WITH CALORIES

You're probably familiar with the physiology of fat loss, but let's quickly review it. Losing fat requires feeding your body less energy than it burns. When you do this, you're creating a negative energy balance or "calorie deficit," and the energy difference between what you eat and what you burn every day usually measured in calories more or less determines how much fat you lose over time.
I know it's trendy right now to claim that calorie counting doesn't work or that weight loss is actually about the quality, not quantity, of calories eaten, but these trends obscure the main issue. Calorie restriction is, and always has been, the key.
"IT'S TRENDY TO CLAIM THAT CALORIE COUNTING DOESN'T WORK OR THAT WEIGHT LOSS IS ACTUALLY ABOUT THE QUALITY, NOT QUANTITY, OF CALORIES EATEN, BUT THESE TRENDS OBSCURE THE MAIN ISSUE. CALORIE RESTRICTION IS, AND ALWAYS HAS BEEN, THE KEY."
You see, your metabolism obeys the first law of thermodynamics. There is no debating this.
When viewed energetically, your body can't tell the difference between the calories in a doughnut and the calories in a gluten-free, soy-free, cholesterol-free, fat-free, GMO-free green juice.
This is how someone may try Nutty Bars, and powdered doughnuts every day. This is why study after study after study has conclusively proven that so long as a calorie deficit is maintained, subjects lose fat regardless of diet composition.1-3
Now, that doesn't mean that macronutrient ratios don't matter. They definitely do, as I'll show a little later. But the point I want to make is that you must know how to maintain a proper calorie deficit over time if you want to lose fat while preserving muscle. Let's look at how to do that.

CUSTOMIZE YOUR ENERGY INTAKE

First, we need to figure out, as accurately as we can, how much energy you're burning every day. This is known as your total daily energy expenditure (TDEE). Here's how I like to do it:

1
 USE THE KATCH-MCARDLE FORMULA

Use the Katch-McArdle formula to determine how much energy your body burns every day, excluding physical activity, which is known as your basal metabolic rate, or BMR. To get this number, you'll need to know your lean body mass.

2
 MULTIPLY

Multiply that number as follows:
  • By 1.2 if you exercise 1-3 hours per week.
  • By 1.35 if you exercise 4-6 hours per week.
  • By 1.5 if you exercise 6 or more hours per week.

3
 CALCULATE 80 PERCENT

Calculate 80 percent of this number. This will create a mild caloric deficit which will allow you to lose about a pound of fat per week without feeling starved or losing too much muscle.

YOUR CALORIC STARTING POINT FOR FAT LOSS

LEAN BODY MASS
 
ACTIVITY LEVEL
 
BMR
 
If you're familiar with this type of calculation, you probably noticed that my activity multipliers are slightly lower than those found in the Katch-McArdle and other similar formulas. 
This is intentional. One of the many things I've learned working with thousands of people is that the standard activity multipliers are just too high for most of us.
Unless you have an abnormally fast metabolism, a standard Katch-McArdle TDEE calculation will leave you wondering why you're losing little-to-no weight despite being perfect with your food intake. 
The multipliers I give above are much better for the average metabolism, and can always be adjusted based on actual results.
I occasionally run into people who lose weight a bit too slowly or quickly on the above multipliers. In the latter case, they'll also experience significant decreases in strength and energy. These issues are easily remedied by decreasing or increasing daily calorie intake by about 100 and reassessing.

THE PERFECT MACROS FOR FAT-LOSS

Now that you know how many calories you're supposed to eat every day, it's time to turn that number into macronutrients. The most common mistake I see here is too little protein and carbohydrate, and too much fat. The result for many is a significant amount of muscle and strength loss.
Let's look at each macronutrient separately.

PROTEIN

The goal while dieting for fat loss is to preserve muscle, and a big part of this is ensuring you're eating enough protein. Fully addressing the science of protein needs would require its own article, so I'll keep it simple here.
I've reviewed the literature and tried many different levels of protein intake while dieting for fat loss, and what I've found works best is in line with research published earlier this year conducted by AUT University in New Zealand.4 These researchers laid it out about as simply as you could hope when they wrote:
"Protein needs for energy-restricted resistance-trained athletes are likely 2.3-3.1g/kg of FFM [1-1.4 grams per pound of fat free mass] scaled upwards with severity of caloric restriction and leanness."
In other words, the leaner you are, or the more calorie-restricted you are, the more protein you need. It's like an inverse bell curve. Figure out where you fit in this range, but bear in mind that I calculate protein per pound of lean mass, not total body weight. So you'll need to use that number you plugged into the BMR calculator earlier.
Here are some guidelines for protein intake and different body fat levels:
  • Super-lean: 10 percent or less body fat (men), 20 percent or less (women): 1.4 g/lb. or higher.
  • Lean: 15 percent (men) or 25 percent (women): 1.2 g/lb.
  • Average: 18-24 percent (men) or 25-31 percent (women): 1 g/lb.
  • Overweight or obese, calorie-restricted: 1.6-1.8 g/lb.
Now you have your daily protein target. Let's look at dietary fat.

DIETARY FAT

High-fat diets are really trendy right now because they are supposedly the best for maximizing testosterone levels and weight loss. This is misleading, though. Yes, switching from a low-fat to high-fat diet can increase free-testosterone levels, but not nearly enough to help you build more muscle.
There are two studies commonly cited as definitive proof that high-fat dieting is superior to high-carb dieting. One demonstrated that when men switched from getting 18 percent of their daily calories from fat to 41 percent, free-testosterone levels rose by 13 percent. The other study, conducted a decade earlier, had similar findings.5,6
Now, that might sound nice, but here's what high-fat hucksters don't tell you: Small fluctuations like this do little to nothing in the way of improving strength and muscle growth. This has been demonstrated in a number of studies.7,8
This is why I recommend you stick to getting around 20 percent of your daily calories from dietary fat when eating for fat loss. To calculate how many grams this is for you, simply multiply your total daily calorie intake by 0.2 and divide this by nine, since there are nine calories in a gram of fat.

CARBOHYDRATES

And now we come to the most maligned macronutrient, the carbohydrate. According to some, this evil little bastard is what makes us fat, and dramatically reducing intake is the best way to lose weight. In action, this simply isn't true.
Research has demonstrated that when protein intake is sufficient, there is no significant difference in weight loss between high- and low-carbohydrate diets.9-12 
As long as you're maintaining a proper calorie deficit, you're going to lose fat at more or less the same rate, whether you're low-carb or not.
Know what will go down as you cut carbs? The quality of your workouts! The less carbs you eat, the lower your muscle glycogen levels will be, which means compromised performance in the gym and miserable workouts. Muscle endurance in particular seems to take the biggest hit.13-14
Furthermore, research has demonstrated that low muscle-glycogen levels impair post-workout cell signaling related to muscle growth. This is particularly detrimental when you're in a calorie deficit because your body's ability to synthesize proteins is already impaired.15,16
There's more, though. Calorie restriction in general is known to reduce anabolic hormone levels, and low-carbohydrate dieting only makes this worse.16 A study out of the Washington University School of Medicine found that a low-carbohydrate diet combined with daily exercise significantly increased cortisol and decreased testosterone levels in athletes.17 
Especially when combined with caloric restriction, this creates a catabolic nightmare that results in more muscle loss while dieting.
The research is clear: as a weightlifter, the carbohydrate is your friend. This is why I recommend you keep your carbohydrate intake high while dieting for fat loss.
IN THE LAST SEVEN WEEKS, MICHAEL HAS GONE FROM 194 LBS AT 8-9% BODY FAT TO 188 LBS AT 7%.

THE EQUATION FOR SUCCESS

Let's tie this all together using me as a case study. I'm currently 188 pounds and my TDEE is about 3,000 calories. Therefore:
  • My daily calorie intake for fat loss = 3000 x .8 = 2400
  • My protein intake = 188 x 1.2 = 225 grams per day
  • My fat intake = (2400 x .2) / 9 = 53 grams per day
  • My carb intake = (2400 - ((225 x 4) + (53 x 9))) / 4 = 255 grams per day
I've actually been cutting on those macros for the last seven weeks and have gone from about 194 pounds and 8-9 percent body fat to 188 at 7 percent without losing more than a rep or two on any of my lifts.
Once you've done the same, your work still isn't finished. That's when it's time to seal your progress for the long term with what's known in bodybuilding circles as a "reverse diet." 
That's what I'll cover in my next article. For now, apply the above ideas and start your shred!
REFERENCES
  1. Sacks FM, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 2009 Feb 26;360(9):859-73.
  2. Due A, et al. Comparison of 3 ad libitum diets for weight-loss maintenance, risk of cardiovascular disease, and diabetes: a 6-mo randomized, controlled trial. Am J Clin Nutr. 2008 Nov;88(5):1232-41.
  3. Nordmann AJ, et al. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med. 2006 Feb 13;166(3):285-93. Review. Erratum in: Arch Intern Med. 2006 Apr 24;166(8):932.
  4. Helms ER, et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014 Apr;24(2):127-38.
  5. Dorgan JF, et al. Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study. Am J Clin Nutr. 1996 Dec;64(6):850-5.
  6. Hämäläinen E, et al. Diet and serum sex hormones in healthy men. J Steroid Biochem.1984 Jan;20(1):459-64.
  7. West DW, Phillips SM. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol.2012 Jul;112(7):2693-702.
  8. Storer TW, et al. Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension. J Clin Endocrinol Metab. 2003 Apr;88(4):1478-85.
  9. Thomson CA, et al. Changes in body weight and metabolic indexes in overweight breast cancer survivors enrolled in a randomized trial of low-fat vs. reduced carbohydrate diets. Nutr Cancer. 2010;62(8):1142-52.
  10. Sacks FM, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 2009 Feb 26;360(9):859-73.
  11. Phillips SA, et al. Benefit of low-fat over low-carbohydrate diet on endothelial health in obesity. Hypertension. 2008 Feb;51(2):376-82.
  12. Johnston CS, et al. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. Am J Clin Nutr. 2006 May;83(5):1055-61.
  13. Skein M, et al. The effects of carbohydrate intake and muscle glycogen content on self-paced intermittent-sprint exercise despite no knowledge of carbohydrate manipulation. Eur J Appl Physiol. 2012 Aug;112(8):2859-70.
  14. Dalton RA, et al. Acute carbohydrate consumption does not influence resistance exercise performance during energy restriction. Int J Sport Nutr. 1999 Dec;9(4):319-32.
  15. Creer A, et al. Influence of muscle glycogen availability on ERK1/2 and Akt signaling after resistance exercise in human skeletal muscle. J Appl Physiol (1985). 2005 Sep;99(3):950-6. Epub 2005 May 5.
  16. Pasiakos SM, et al. Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults. J Nutr. 2010 Apr;140(4):745-51.
  17. Cangemi R, et al. Long-term effects of calorie restriction on serum sex-hormone concentrations in men. Aging Cell. 2010 Apr;9(2):236-42.
  18. Lane AR, et al. Influence of dietary carbohydrate intake on the free testosterone: cortisol ratio responses to short-term intensive exercise training. Eur J Appl Physiol.2010 Apr;108(6):1125-31.