There are, as I see it, four classic ways to be lean:

1. There’s hunger-striker lean, achieved with starvation, and not recommended by any major medical organization.

2. There’s heroin-addict lean, achieved most notably by Iggy Pop during the early seventies…and mysteriously retained for decades after he quit using drugs.

3. There’s marathon-runner lean, which is a lot healthier than the first two but probably not what you had in mind when you clicked on this article.

4. And there’s cover-model lean, which I assume everyone reading this aspires to.

That fourth look—made famous by the men who fronted Men’s Health magazine in the nineties and early 2000s—is achieved with a combination of the most muscle you can maintain and the lowest body-fat percentage you can achieve. As we discussed in “How Much Muscle Can You Gain?”, the two processes are inextricably linked. You can’t gain a lot of muscle without also gaining some fat, and you can’t lose a lot of fat without sacrificing some muscle. 

Since we addressed muscle building in the first article, we’ll talk about losing fat here.

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Lean in

Let's start by examining how lean a man can naturally get, based on the best example we have: natural bodybuilders. That’s the full shred, with abs that are visible from space and skin so tight you hurt your fingers trying to grab enough to pinch.

Related: The Men's Health Anarchy Abs Workout: The Fastest Way to Chisel a Six Pack!

Eric Helms knows what it’s like to get down into that range. He’s a Ph.D. candidate at Auckland University of Technology in New Zealand and a pro natural bodybuilder who has reached an estimated 5 percent fat at a body weight of 181 pounds. That means he carried just nine pounds of fat on his 6-foot frame.

How difficult is it to get to that point?

“At the end it’s harder than boot camp,” Helms says. He means it literally: He served in the Air Force, and has compared notes with friends from other military branches.

Related: 4 Daily Exercises Every Navy SEAL (and Every Fit Guy) Should Do

We’ll get to the details in a moment. First, though, we’ll take a closer look at the challenge of body-fat reduction, what the leanest of the lean do to reach that impeccable condition, and what guys like us can learn from their experiences to help achieve a realistic body-fat level—one that probably won’t get your picture in a supplement ad, but will definitely get you closer to that ideal than you are now.

Long road to a hard body

The average American male has an estimated 28 percent body fat. (I say “estimated” because dissection is the only way to know for sure. That’s a little extreme, even for aspiring underwear models.) Even guys at “normal” weight—meaning they have a body-mass index lower than 25—are at 22.7 percent fat, on average.

A relatively strong and fit gym rat, Helms says, probably has body fat in the range of 12 to 16 percent. That guy probably can’t see his abs yet—not all of them, anyway, and not all the time. But he has the consolation of knowing he’s in the top 5 percent of all American men. (Seventeen percent fat is the cutoff for the 5th percentile.) To get from there to a pose-worthy physique, with low-single-digit body fat, Helms says he’d probably need to lose 20 to 40 pounds.

Even a working fitness model, someone whose living depends on his abs and is almost always the best-built guy in the room, is probably 10 to 20 pounds away from being as lean as he could possibly be.

Not all of that lost weight will be fat. In three recently published case studies of competitive natural bodybuilders, they lost a lot of muscle—between 20 and 43 percent of the total weight they dropped.

Related: 5 Bodybuilding Techniques That Have Stood the Test of Time

Helms thinks those numbers sound a little high. “I would say the normal range is between 20 and 30 percent,” he says. “If you lose 20 percent or lower, you did a good job holding onto muscle mass.” Still, there’s no way to get around this fact: The leaner you get, the higher the proportion of muscle you’ll lose.

The key, Helms says, is to give yourself plenty of time to reach your goal, no matter what it is. A bodybuilder starting with low-double-digit body fat needs, on average, about six months to become “totally peeled.” That’s with a diet that gets progressively restrained and a workout program that becomes incrementally more time-consuming. By the end he’ll be eating just nine to 12 calories per pound of body weight while lifting four to six days a week and doing some form of cardio four to seven days.

The leaner you get, the harder your body fights back, and that’s when it starts to mess with your mind. (Fight back with 3 Ways to Build Extreme Mental Toughness.)

“Emotional stress levels get much higher than normal, especially at the end,” Helms says. “Libido disappears at a certain point. Lethargy hits pretty bad, and irritability and obsessiveness get out of control in most people.”

“Good enough” is actually great

That leads to this surprising advice: “The average guy simply should not try to cut to 4 to 5 percent body fat,” Helms says.

For one thing, the final result may not give you the look you wanted. Picture this: You start out as a 175-pounder with 14 percent fat. You lose 20 pounds to get down to 5 percent. Your loss includes 15 pounds of fat and just 5 pounds of lean tissue. The friends who see your shirtless selfies on Instagram will indeed marvel at your magnificent, ultralean physique.

But to the rest of the world, the people who see you every day? Unless you work as a lifeguard or a stripper, or find some other way to spend a lot of time undressed, you’ll just look like a guy who lost 20 pounds for reasons that mystify most of the people you know.

For another, it’s unsustainable. “Most guys who diet to sub-8 percent just end up overeating themselves back to where they started, or higher, within weeks of achieving the goal,” Helms says.

Related: 6 Guys with Ripped Abs Tell You Why It’s Not Worth It

A minuscule percentage of males can maintain super-low body fat, but Helms estimates it’s one in a thousand. For everyone else, it’s psychologically damaging to try. “It lends itself toward disordered eating,” he says.

A more reasonable goal is to work toward your “settling point.” That, Helms says, is the lowest body-fat level you can sustain while still making progress in the weight room and without making yourself miserable. Whatever it is, it is. It’s not a measure of your courage or self-discipline.

And most of all, it’s not a contest. One guy may be able to sustain 8 percent fat with less effort than it takes you to stay at 12 percent. That’s just the luck of the draw, and very few of us are gifted with a settling point in the permanent-six-pack range.

But that’s not necessarily a bad thing. “I joke that when I’m single-digit body fat, if my wife walked in front of me completely naked, holding a pizza, I wouldn’t notice that she was naked,” Helms says.

So that’s your standard: If you spend more time thinking about pizza than sex, it’s probably time to back off your diet and start enjoying life with the physique you worked so hard to build.

Lou Schuler is an award-winning journalist and the author, with Alan Aragon, of The Lean Muscle Diet.