What would it take for you to let me help you build your best body ever in as little as 12 weeks?

”That was the appeal in 1999’s “Body for Life,” the book by Bill Phillips that launched the fitness transformation industry in the U.S.

Fast forward to today and those 12 weeks have been compressed to as little as 21 days, as transformation challenges — once catering mostly to male couch potatoes looking to shed the belly — have exploded, with trainers from every fitness genre from Pilates to boot camps, promoting challenges for everyone, with guidance available 24/7.

No longer confined to books and DVDs, today’s transformation trainers are practically in your pocket, providing tips and motivational memes in daily emails, sending push notifications about new workouts on their apps, and providing live chats and cooking videos on Facebook and YouTube.

Challenge leaders are now more than instructors, they’re mentors, lifestyle coaches and virtual BFFs. And it’s this close connection with followers — both online and in person through massive meet-ups — that makes many of these makeovers possible, says Autumn Calabrese, creator and trainer of Beachbody’ s best-selling 21-Day Fix workout and nutrition plan.

“When I first started as a trainer, we didn’ t have options like Facebook,” she says. “Now I can advise [people] on what they are struggling with,” whether it’s busting through a plateau or finding a way to eat healthy when they’ re pressed for time.

Calabrese’ s audience is so engaged that they will cycle through her 21-Day Fix challenge several times. Many are no longer going from fat to fit, but from fit to even fitter, prompting her to release more intense diet and workout regimens, such as 21-Day Fix Extreme and The Master’ s Hammer & Chisel, programs that she has used to prepare forbikini fitness competitions or video shoots.

Why are we so hooked on challenges?

A big part of the draw is the dramatic before-and-after photos, with ordinary people suddenly showing off a slim waist or more defined arms and abs. People see these photos with a short time frame attached to them, and it taps into their need for instant gratification, says trainer Brad Schoenfeld, Ph.D., CSCS, and author of the forthcoming book “Strong and Shapely.”

“They say, ‘If I can do that in 90 days, I’m signing up.’

”Indeed, these photos serve as a kind of guarantee — real or not — that the effort someone puts in will get him what he wants, says Dr. Tim Benson, a Harvard-trained psychiatrist and former athlete who specializes in fostering resilience in athletes and entrepreneurs. “Many need this kind of guarantee to move forward.”

Of course, there are no guarantees that your results will mirror those in the photos. A 2005 study published in the monthly journal of the American College of Sports Medicine found a huge swing in both men and women’ s results from the same resistance training program, with some participants showing little to no gain in strength and muscle mass, and others showing profound changes, increasing muscle size by over ten centimeters and doubling their strength.

“I carry out studies all the time,” Schoenfeld says, “and there can be a huge difference in individual response. Some people on the same program have a 20 percent increase in muscle mass, while others have zero.”

Moreover, as some bloggers have pointed out by pushing out their belly and using dark makeup to draw the shading of rippled abs, transformation results photos aren’ t always what they seem.

But the offer of big changes in a short period of time does make someone more likely to embark on a fitness program, experts say, because it allows them to mentally come to terms with the sacrifices they will have to make for a set period of time to see results.

And ultimately, Calabrese and Schoenfeld say, challenges appeal to our competitive nature.

We all want to see if we can do better than the next guy, whether it’ s at work, on the playing field or just on the scales.

Indeed, it’ s this healthy competition that is funneling millions of dollars to challenge sites such as DietBet that offer a payout to those who “win” by meeting their percentage weight loss goal during a challenge, and a small financial loss to those who fail.

Transformation challenges: Then

Phillips, founder of Muscle Media magazine and supplement company EAS, has been credited with jumpstarting the fitness transformation industry with his “Body for Life” diet and exercise book.

The notion that you could change your physique so radically in three months got millions to the gym, making it one of the best-selling non-fiction books of all time. Its advice was so sound that it spawned a “Body for Life for Women” 10 years later, and 17 years from publication, it still gets a four-star rating on Amazon.

Phillips understood what motivates people, Schoenfeld says, including the power of before and after photos, “real-world proof” as he called them, as well as the rallying power of competition.

To kick off the program and get people sending in their before and after photos (which helped propel sales) he offered up his blood-red Lamborghini Diablo sports car as a transformation grand prize.

Today, trainers are still using this model for their challenges, offering up trips, gear and other prizes on social media to those who post their makeovers as #fitspiration for others.

“I can say that you can lose 15 pounds in 21 days, but [these photos] are really what gets people engaged and able to believe what I say and trust the process,” Calabrese says.

Just like today’s trainers offering up round-the-clock support, Phillips also had the relatively new idea of a telephone helpline and website tips for staying on track.

Transformation challenges: Now

Of course, much has happened in the fitness industry since “Body for Life” was released. Advances in knowledge about training and nutrition have changed challenge recommendations, with more trainers offering up shorter but more intense interval workouts, go-anywhere bodyweight exercises, and plyometrics to help build bone density and prevent bone loss.

“We can get away with 30-minute workouts now by keeping you in a cardio zone when you’re lifting weights. You’ re burning fat while you’ re building muscle,” says Calabrese. “It’s about working out smarter, not longer.”

The nutritional recommendations have evolved too, as more people have shunned the low-fat diets and plain chicken breasts of the 1990s, embracing healthy fats and juicing, as well as vegan, paleo and other specialized diets.

And most importantly, there are a lot more paths to fitness transformation these days. Rather than just offering one-size-fits-all diet and workout plans, today’ s trainers and coaches are serving up challenges for just about every interest, from Pilates and running to yoga and meditation — each with a different yardstick for success, including goals tied less to perfection and more to performance, overall flexibility and mental and physical ease.

There’s more emphasis, Benson says, on “How do I continue to grow?” and conquering your own mental roadblocks, rather than just emulating someone else’ s physique.

And just as there are more paths to fitness, there are more fitness gurus to lead you down that healthy path — particularly a lot more women, who have excelled in building huge communities of men and women by blogging, answering their fan’ s questions in live chats, running challenge support groups on Facebook and checking in with daily motivation on Instagram, Snapchat and other types of social media. It’s about finding who you can relate to.

“There are days when I don’t want to work out, and the fact that I’m sharing that on social media makes it feel more realistic to people,” Calabrese says. “People see that I do have hard days. I’m a single mom. I take care of myself. I’ve had a C-section. My body is not super-human.”

The technology of transformation

Indeed, it’s technology that’ s fueled the growth of transformation challenges, by giving us more intimate and immediate connection to top fitness trainers, and an instant online support group of like-minded people.

“There’s a saying that we can go faster alone, but we can go farther together,” Benson says. “There’s something about being part of something great that fuels us to not give up and be an inspiration to others.”

Calabrese might have as many as 60,000 people join her in a monthly Facebook challenge. Once closed, these challenge forums are a private place her followers turn to when they need advice on how to handle eating out and sticking to a nutrition plan, or how to handle soreness, or deal with lack of progress on the scale. It’s also where they share their weekly progress photos and check-ins, which Calabrese says is where many people who think they are not making progress often have it pointed out by others.

“Sometimes the changes are so gradual you don’ t even see them,” she says.

Joining a group also prods us to keep moving, so we don’ t fail the group or embarrass ourselves.

New research from the University of Pennsylvania shows that when people join a social fitness network they exercise 100 percent more than those who work out without online buddies. Seeing how often others exercise and what kind of activity they’re doing encourages more frequent workouts, as well as the belief that regular exercise is the norm among your peers, says lead author Damon Centola, Ph.D.

Are we becoming transformation junkies?

Of course, our obsession with transformation — particularly the physical results — isn’t always healthy. While posting before and after pictures and getting feedback from an online community can be inspiring — and even breed confidence — spending too much time perusing others’ perfectly toned bodies can be an unhealthy habit.

Studies show that men and women viewing these types of photos tend to feel worse about themselves immediately after, and this attitude can lead to compulsive exercising, says Heather Hausenblas, faculty member of the Brooks Rehabilitation College of Healthcare Sciences at Jacksonville University and author of “The Truth About Exercise Addiction: Understanding the Dark Side of Thinspiration.”

“We tend to equate health with six-pack abs and that’ s not always the case,” Hausenblas says. Healthy, she says, is about the habits you keep, not the number on the scale after you blitz through an intense program.

It’s important, experts say, for people launching on a transformation challenge to make it work for them. If the exercise on a plan is too intense or painful, it should be modified, so those with a lower baseline fitness level don’ t get hurt.

“When people get hurt it can taint their mindset [about exercise] for life,” Schoenfeld says. For maximum results, he says, you have to tailor the challenge to an individual’ s needs and abilities. For instance, he says, some people might have better results with more repetitions and less weight, while others should bear a greater load over fewer reps.

Moreover, there should be some room for flexibility if a lifestyle program is going to last more than a few weeks, experts say. Treadmill haters should be able to cycle or do the dance cardio they love, and you should be able to swap out meals in a meal plan within certain parameters to accommodate your tastes and make it fit in your life.

“If you don’ t find the fun in fitness, you’re not going to make it stick,” says Calabrese.

Indeed, despite her program’ s name, Calabrese says she doesn’ t think of the 21-Day Fix as a destination, but rather a start on the road to a healthy lifestyle, with the visible results from a quick start lending greater motivation to maintain a healthy lifestyle.

Transformation starts in your head

Just as important, Benson says, is laying the mental foundation for your transformation.

You have to make conscious choices and come to terms with the things that may be holding you back, he says, as well as know what will carry you forward when the going gets tough.

  • What will you have to give up to achieve your goal? Will you have to give up those happy hours with your friends, the trips to your favorite ice cream place or some of the time spent sleeping in in the mornings? What do you need to give up and grieve in order to move forward with a challenge?
  • You also need to look for the why, Benson says. Why do I want to lose those 20 pounds? How will it make me feel? “People who have connected their whys with their emotions,”he says, “will be more successful in achieving their goals.”
  • And once you’ re in a challenge, he says, you have to work on a plan of repetition, resistance and reflection. Repetition is making sure you are doing something often enough to make it a habit. Resistance is making sure you are being adequately challenged and seeking feedback on your progress. Lastly, reflection involves taking the time periodically to look at how far you’ve come and what you’ve learned along the way and to make any adjustments, just as an athlete reviews film footage to see where things bogged down or succeeded.

“I always drive home for people that we focus too much on motivation” to muscle through a challenge, Benson says. “Motivation can be connected to emotions, and those can be unpredictable at times.”

A better approach, he says, is to focus on taking small consistent steps and letting their momentum move you forward.

“Being fit is a lifestyle,” agrees Calabrese. “There should be no beating yourself up for having a cheat day or missing a workout. Just because you had a piece of cake at your kid’ s birthday doesn’ t make you a failure. Enjoy it and go back to your clean eating. That’ s real life.”

Are You Addicted to Transformation?

Getting regular exercise and challenging yourself physically is undoubtedly healthy, but it can be taken to extremes. If you find yourself agreeing with three or more of the seven criteria below, you may have a problem with “exercise dependence,” according to Heather Hausenblas, faculty member of the Brooks Rehabilitation College of Healthcare Sciences at Jacksonville University, and author of “The Truth About Exercise Addiction: Understanding the Dark Side of Thinspiration.”

  1. Tolerance – Are you constantly having to increase the amounts of exercise you are doing to feel the same effects?
  2. Withdrawal – Do you feel withdrawal symptoms such as anxiety, fatigue, a short temper or agitation when you can’ t exercise?
  3. Intention effect – Are you exercising in larger amounts for longer periods of time than intended on most trips to the gym?
  4. Lack of control – Do you have difficulty scaling back the duration and intensity of your exercise routine?
  5. Time – Do you find yourself funneling huge chunks of time both day and night into fitness activities? (More than two hours a day is a red flag.)
  6. Reductions in other activities – Are you giving up social engagements that don’ t involve exercise, cancelling scheduled activities or showing up late for work in order to exercise longer?
  7. Continuance despite injury – Are you taking enough time off to heal when you have an injury, or do you muscle through the pain, despite your doctor’ s objections?