Michelle Obama in Jason Wu gown at the Inaugural Ball

Michelle Obama flaunting her fit arms in a Jason Wu gown at the Inaugural Ball. Photo: Stan Honda, AFP/Getty Images

Just because fall fashion usually consists of multiple layers which tend to hide post-Labor Day flab, beware the office heating system -- it will have you shedding your cardigan in no time flat, leaving you with no choice but to bare naked arms for all your coworkers to see.

To deal with the year-round exposure of your maybe less-than-buff guns, you'll unfortunately need to flex your muscles, even in the colder months.

Luckily, Michelle Obama's personal trainer Cornell McClellan is spilling the beans on the secret behind the First Lady's banging arms -- and the rest of her body -- in the October issue of Women's Health.

McClellan, from Chicago's Naturally Fit studio, has been training Mrs.O since 1997. "She's truly committed herself to the importance of health and fitness," he tells the magazine, before revealing Obama's total body fitness plan, which includes weight training combined with bursts of cardio during all four seasons.

To keep Obama's arms looking great in everything from summer vacation shifts for Martha's Vineyard, Mass. to her asymmetrical Jason Wu inaugural gown (watch the one-shoulder trend continue this fall), McClellan guides Obama through a 9-minute "arm-shaping superset" with a weighted bar to carve her biceps and triceps.

And to target her legs and hips, Obama does four to five rounds of lunges while holding dumbbells and 50 reps of brutal mountain climbers per leg for cardio. (Remember the last two when you're trying to squeeze back into your favorite skinny jeans after months of freedom in loose dresses.)

In addition to these exercises (which are all shown in detail on WomensHealth.com), McClellan says he also challenges Obama with bench presses, hip raises, rows, jump-roping, kickboxing and body-weight calisthenics, plus advises her on a diet including whole foods, produce, protein and lots of water.

So, just when we thought we could safely enjoy creamy soups and starchy seasonal treats, the First Lady is setting the bar(bell) high.

But if we can look as fit as she does all the time -- check out her toned body in this gallery on her style evolution -- we might be ready to drop the fries.