The storied six-pack—a lean, muscular, and well-defined midsection—is a ubiquitous goal for people who want to get in shape; people like how it looks, all the fittest celebrities have one, and it's an easy shorthand for describing a particular level of fitness that's considered an aesthetic ideal.
Louis Sepulveda, a Tier 3 personal trainer at Equinox fitness club in Darien, Connecticut, can testify as much. "Almost every client I have, during their fitness assessment, would mention wanting a six-pack—or at least having a flatter tummy," he says. But getting that kind of definition isn't a simple matter of going from fat to fit.
"Everyone, for the most part, is born with the same muscles that make up the ab complex," Sepulveda explains. "But you need to lose body fat in order for definition to show. For someone who carries more visceral fat—fat stored within the abdominal cavity—having a six-pack can be laborious."
In other words, thousands of get-ups, planks, or bicycle curls might give you abs of steel, but if you want them to pop out like Brad Pitt's in Fight Club, you'll have to eat at a deficit (a diet low in calories and high in protein) until your body has burned enough fat to reveal them. And despite all those internet ads touting "one weird trick to blast belly fat," alas, says our trainer, there's no such thing as spot-reducing: "You can't target a specific area to burn fat."
And because fat tends to come off in reverse order (the first place you store it is the last place you'll lose it), if you're unlucky enough to store extra fat in your belly, you may not be able to achieve that kind of definition without also dropping to a dangerously low level of body fat, something Sepulveda cautions strongly against.
"Having visible abs becomes unrealistic when you're striving to go below a normal level of body fat," he says. "As much as everyone hates fat, you need it to live. It's a source of energy, it supports brain and nerve function. Having very low levels of body fat can become unhealthy."
In men, extremely low levels of body fat are associated with risks including dangerously low heart rates, a decline in testosterone levels, and poor recovery. For women, too little body fat can result in amenorrhea (loss of menstrual cycles), which in turn is a major risk factor for developing osteoporosis.
And much as we may appreciate the way it looks, the truth is that six-pack abs are actually pretty useless as a measure of fitness. A six-pack indicates absolutely nothing about your speed, your strength, your stamina, your flexibility, or even your level of overall health. All it means is that you have a lean enough midsection for your musculature to show—which is why Sepulveda encourages his clients to focus on goals beyond the coveted six-pack.
"I have my clients strengthen their trunk stability, working all the muscles located in the torso. Adding plank variations, rotations, chops, and lifts to your workout routine will make your abs, obliques, and lower back a lot stronger, not to mention less prone to injury," he says.
So if it turns out that a visible six-pack is out of reach for you (or if you're not interested in adopting the kind of restrictive diet it takes to get and maintain one) there are still plenty of good reasons to work that core. Having strong abs will serve you well, both in and out of the gym—and that's true regardless of whether you ever get lean enough to see them.