How low in calories can you go to drop fat rapidly without losing muscle or tanking your testosterone levels? Here's the exact math you need.
Every Lifter's Greatest Fear
To lose fat you need to create a caloric deficit through diet and training. That just means you need to eat fewer calories than your body requires to maintain its current state, and/or use up more calories via exercise.
The problem is, a caloric deficit also opens the door to every natural lifter's greatest fear – muscle loss. Fortunately, you can destroy fat without destroying the gains that you've worked so hard for.
How Low Can You Go?
"What's the most aggressive fat loss diet I can follow without losing muscle?" It's a common question. Unfortunately, in today's world of instant credibility, every 20-year old with Anavar and abs is suddenly an expert.
Even worse, many of the studies analyzing the maximum rate of fat loss use obese or untrained test subjects, not dedicated lifters. This begs the question: how aggressively can you lose fat without dropping muscle if you're already in shape?
One study set out to examine the body composition and power performance in lean, 20-35 year old male athletes using an aggressive fat loss deficit. In the aggressive fat loss group, athletes were able to improve performance and reduce fat mass with a 24% calorie deficit composed of a high-protein, lower-carb diet over a four-week span (1).
The Study Specifics
The study used 15 male (national and international level) athletes from the jumping and short distance (100m-200m) events with at least five years experience in competitive athletics. In other words, these were elite track and field competitors with some serious horsepower, not a few college kids sipping on cheap beer and living off pizza.
- 8 participants were assigned to a high weight reduction group: calorie restriction = 750 calories lower than maintenance, a 24% deficit.
- 7 participants were assigned to a low weight reduction group: calorie restriction = 300 calories lower than maintenance, a 12% deficit.
Overall, body mass decreased by a mean of 5 pounds. Athletes with a body fat percentage of 10% or more (think visible abs, but not shredded) were able to preserve fat free mass better than leaner individuals. Serum testosterone levels, cortisol, and sex hormone binding globulin didn't change significantly. That's good news.
Hormonal balance is a crucial part of this fat loss formula. Healthy testosterone levels are essential for your body to perform optimally (not to mention your mind). Studies confirm that healthy testosterone levels in men lead to both an increase in lean muscle mass and a reduction in body fat (2).
But it doesn't stop there. Fat loss combined with a healthy hormonal balance wasn't all that their diet had to offer. The competitors who participated in the high weight reduction group actually improved in their sport.
The jumpers saw improvements in their jump distance, and the sprinters reduced their sprinting times. All this indicates an improvement in relative strength (you can jump and sprint better when you lose excess fat) – an important component of athletic performance when you're moving your body through space.
Boiling down the results of this groundbreaking study we see that reducing caloric intake by 24% (through mild carb reduction and increasing protein intake) will lead to about a 1.25 pound reduction in fat loss per week, without negatively affecting muscle mass or hormonal balance, while also improving performance.
Now, Do It Yourself
As with any successful diet program (for weight gain or weight loss) you'll want to start by figuring out what your caloric maintenance is. So let's find your baseline. To be super accurate, you could spend a couple weeks tracking your intake at maintenance, but this equation should get you started with a rough estimate:
Bodyweight in pounds x 15
So for example, let's say you weigh 200 pounds:
- 200 pounds x 15 = 3000 maintenance calories per day.
- Using a 24% calorie deficit, you'd multiply maintenance calories by .76 because 100% minus 24% gives us 76%.
- So 3,000 calories x .76 = 2280 calories per day.
Pretty simple, right?
Remember, according to the study, for the best results you'll want to reduce your caloric intake by 24% per day with about 80% of that calorie reduction coming from carbs. If that's too many percentages of percentages, then just remember to keep your protein intake high. We'll cover the macros in the next section.
Even though the study lasted 4 weeks, you could potentially continue with this caloric deficit until you reach your fat loss goals... as long as the progress continues.
Still, I recommend you take your diet in 4-week chunks. The leaner you are, the harder it is to get even leaner, and the more muscle you'll lose when using an aggressive approach. In this case, track your numbers carefully and cycle in a maintenance week after 4-6 weeks of cutting if your numbers start to tank.
Using our 2,280 calories per day example, you'll want your diet to consist of:
40% calories from protein
- 2280 x .40 = 912 calories
- 912 calories divided by 4 calories per gram = 228 grams.
So you'd eat 228 grams of protein per day.
30% calories from carbs
- 2,250 x .30 = 684 calories
- 684 calories divided by 4 calories per gram = 171 grams.
So you'd eat 171 grams of carbohydrates per day.
30% calories from dietary fat
- 2,280 x .30 = 684 calories
- 684 calories divided by 9 calories per gram = 76 grams.
So you'd eat 75 grams of fat per day.
This adds up to:
- 2,280 calories per day
- 228 grams of protein
- 171 grams of carbs
- 76 grams of fats
You'll cycle in a maintenance week or two depending on the amount of time you've spent doing it and the feedback you're getting from your body. Keep an eye on the scale and adjust your caloric intake upwards if you're losing more than 2 pounds per week after a few weeks on the program.
Remember, reckless fat loss can cause muscle loss, which is the opposite of what you want. This fat loss program is calculated to help you keep the most muscle mass and healthiest hormone levels to keep you performing at your best.
Maintenance Phase Macros
Using the 3,000 caloric maintenance example above, your maintenance week will look like this:
30% calories from protein
- 3,000 calories x .30 = 900 calories
- 900 calories divided by 4 calories per gram = 225 grams.
So you'd eat 225 grams protein per day.
40% calories from carbohydrates
- 3,000 calories x .40 = 1200 calories
- 1200 calories divided by 4 calories per gram = 300 grams.
So you'd eat 300 grams of carbs per day.
30% calories from fats
- 3,000 calories x .30 = 900 calories
- 900 calories divided by 9 calories per gram = 100 grams.
So you'd eat 100 grams of fat per day.
This adds up to:
- 3000 calories per day
- 225 grams of protein
- 300 grams of carbs
- 100 grams of fat
Remember, the maintenance week is simply meant to act as a recovery week after 4 consecutive weeks on the fat loss diet. Stay consistent. Keep an eye on the scale. Make adjustments where necessary and you'll lose fat, not muscle.
Here's Why It Works
This diet plan allows for a reduction in your carb intake without the negative affect of a hormonal imbalance. Carbohydrates and dietary fats are the two key macros for healthy testosterone levels, which are necessary for optimal fat burning and muscle building processes.
Even though carbs are restricted, you still supply your body with enough to keep your hormonal balance from putting you in a catabolic state.
For instance, a bodybuilder who needs to decrease both his calories and carbs will dramatically lower them before his "peak week" during competition prep. But for most of their prep, they'll stick to a similar fat loss formula as the one above to maintain muscle mass while consistently losing about a pound per week.
A natural competitor will spend the majority of his bodybuilding show prep with testosterone levels relatively high. But in the last couple weeks, with a major caloric deficit and carb deficit, hormonal balance flies out the window and of course isn't sustainable, which is why bodybuilders will "reverse diet" after a show.
As hormonal balance is reinstated through a greater caloric intake (mostly through increased carbs) the bodybuilder begins to add slabs of muscle mass to his frame again, and will hopefully outdo himself the next time he steps onto the stage.
A Super Simple Recap
So, what's the most aggressive fat loss diet you can follow without losing muscle? Just reduce your maintenance caloric intake by 24%, primarily through a carbohydrate drop. Then, up your protein intake a bit.
If you're in the market for a fat loss diet that won't cost you muscle, won't jack with your testosterone, and will actually improve your performance, give this protocol a shot.
Get your maintenance calories down on paper (or app) and follow the formula to get your target numbers. Keep at it for 4-weeks and then make adjustments if necessary.
- Huovinen, H. T., Hulmi, J. J., Isolehto, J., Kyröläinen, H., Puurtinen, R., Karila, T., Mero, A. A. (2015). Body Composition and Power Performance Improved After Weight Reduction in Male Athletes Without Hampering Hormonal Balance. Journal of Strength and Conditioning Research, 29(1), 29-36. doi:10.1519/jsc.0000000000000619
- oung, N. R. (1993). Body composition and muscle strength in healthy men receiving testosterone enanthate for contraception. Journal of Clinical Endocrinology & Metabolism, 77(4), 1028-1032. doi:10.1210/jc.77.4.1028