The 4-Hour Body Workout: On the Colorado Experiment and Tim Ferriss

A while back, I read a book called The 4-Hour Body: An Uncommon Guide to Rapid Fat-Loss, Incredible Sex, and Becoming Superhuman.

The blurb claims that it’s the “result of an obsessive quest, spanning more than a decade, to hack the human body. It contains the collective wisdom of hundreds of elite athletes, dozens of MDs, and thousands of hours of jaw-dropping personal experimentation.”

The trailer below gives you a flavor of what the book is about.

One of the chapters in there that caught my eye is called From Geek to Freak: How to Gain 34 Pounds in 28 Days.

In it, author Timothy Ferriss describes his experiences with a month-long training program based on the so-called Colorado Experiment.

Despite just two 30-minute workouts per week, for a total of 4 hours of gym time, Tim claims that he gained 34 pounds of muscle in 28 days while also losing 3 pounds of fat.

What was the Colorado Experiment? And is it really possible to gain 34 pounds of muscle in 28 days using the 4-Hour Body workout?

What Was the Colorado Experiment?

The Colorado Experiment wasn’t really an experiment. It was a giant marketing exercise by Arthur Jones, the inventor of the Nautilus range of exercise machines.

Like Ferriss, Jones was a marketing genius. The fact people are still talking about the Colorado Experiment decades later shows what a thorough job he did.

The major purpose of the study, according to Arthur Jones, was to show “that the growth of human muscular tissue is related to the intensity of exercise” and that “increases in strength and muscle mass are rapidly produced by very brief and infrequent training, if the intensity of exercise is high enough.”

Basically, he wanted to show that high-intensity training (HIT for short), done using his own brand of Nautilus machines, was the fastest and most effective way to build muscle. 

At a time when training for two hours twice a day was considered normal, Jones caused controversy when he claimed that you could get better results with shorter workouts, but with each set taken to the point of momentary muscular failure.

“The set should be terminated only when it is impossible to move the weight in any position,” Jones wrote in one of his Nautilus Bulletins. “When the bar literally drops out of your exhausted hands.”

The “experiment” ran for a period of 28 days back in May 1973. In it, Casey Viator, who was the youngest ever winner of the AAU Mr. America contest in 1971, allegedly gained 63.21 pounds of muscle and lost 17.93 pounds of fat. And he did it all using only Nautilus equipment.

Sixty three pounds is a lot of muscle, far more than most people can expect to gain in a lifetime. Viator reportedly did it in just 28 days. What’s going on?

How Arthur Jones Stacked The Deck

Prior to taking part in the Colorado Experiment, Viator almost died from an allergic reaction to an anti-tetanus injection. He also hadn’t trained for five months, and ended up losing a large chunk of muscle.

Before the experiment started, Casey was also dieting hard. He was eating less than 800 calories per day after being told, in his own words, to “lose as much as I possibly could.”

“Going that low, I was emaciated,” he says. “My eyes were sunken three inches into my head! Then during the experiment I got a cash incentive for every pound I gained, so I had great reason to put on weight.”

He ended up losing over 30 pounds, with much of that lost weight coming from muscle.

The idea was to stack the deck so that Casey lost as much muscle as possible. Then, when he started training and eating properly again, it would make his gains that much bigger. Due to a phenomenon known as muscle memory, rebuilding lost muscle happens a lot faster than gaining in the first place.

Was Casey Viator Taking Drugs?

Google around for information about the Colorado Experiment, and you’ll come across a lot of debate over whether or not Casey Viator was taking anabolic steroids at the time.

Here’s what Bill Starr, the guy who popularized the 5×5 training programs that were popular a while back, had to say on the subject:

One of Arthur’s greatest marketing schemes revolved around the amazing progress that Casey Viator had made in just a month while using Nautilus machines exclusively. It was called the Colorado Experiment and helped Jones move a lot of equipment. What the public didn’t know was that Casey was taking steroids the whole time without telling Arthur and he was also sneaking out to a local YMCA to train with some real weights. I know this because Casey told me so.”

Bill Starr

For Casey’s part, he says he was clean. While he doesn’t deny drug use in his bodybuilding career, he does claim not to have used them during the Colorado Experiment.

Here’s what Casey told Randy Roach, author of Muscle, Smoke & Mirrors:

I didn’t need them in that situation. I was gaining muscle I already had. Arthur was offering me X number of dollars per pound of muscle gain. It was the equivalent to the price of a Corvette at the time. If Arthur would have thought that I was taking steroids, the deal was off.”

Casey Viator

Kim Wood, former strength coach and strong anti-drug advocate, also says that it would have been difficult (but not impossible) for Casey to have taken drugs since Wood’s brother was staying with Casey at the time to monitor the no-drug clause.

However, unless you’re literally following someone around 24/7, going to the bathroom with them, sleeping in the same bed as they are, you’re not going to know if they’re secretly taking a few pills here or an injection there.

What’s more, anabolic steroids weren’t illegal back then, so Casey didn’t have to worry about breaking the law. You could also get the drugs prescribed by a doctor, so you knew what you were getting, rather than a counterfeit product containing who knows what.

You still need an iron-fisted work ethic combined with an almost superhuman level of persistence and dedication. Drugs don’t change that. But they do allow you to gain muscle at a rate that would have been impossible without them.

If I was being paid a substantial amount of money for every pound of muscle gained over a 28-day period, and there was an opportunity to take some drugs to speed things up, I’d be first in line.

Did Casey Viator Really Gain 63 Pounds of Muscle?

Casey’s weight increased by a little over 45 pounds during the 28-day experiment. However, he also reportedly lost 18 pounds of fat, for a total muscular gain of 63 pounds.

Given that he only trained 14 times, with each workout lasting a little over half an hour, that’s an average increase in muscle mass of 4.5 pounds per workout. None of which even remotely passes the reality check.

The only way to actually measure your body composition (as opposed to estimating it) is through carcass analysis, where all the fat is stripped out from a dead body and weighed.

There are various body fat tests out there, such as DEXA and body fat scales, which give you a rough idea about the amount of muscle mass you gain over time. But even today, these tests are not very accurate.

Casey’s body composition was estimated by something called a whole-body potassium counter, which works by measuring the radiation given off by potassium in the body’s fat-free mass.

While whole-body potassium counters were state of the art back in the 1970’s, their use has declined over the years. That’s possibly because the results, if the estimates of Casey’s body composition are anything to go by, are complete bullshit.

If you look at Casey’s pictures, which you can see more of in the video below, there’s no way he’s 2.47% body fat. Add another ten percent to that number and you’re probably closer to the mark.

Every so often, somebody invokes the Colorado Experiment as undeniable proof that brief and infrequent training is the way to go, usually in an attempt to sell some new variation of HIT to a new generation of unsuspecting rookies.

All of which brings me on to the subject of Timothy Ferriss and The 4-Hour Body workout.

The 4-Hour Body Workout

Here’s the workout that, along with a diet providing 5,000-8,000 calories per day, Tim claims is responsible for his remarkable results.

Pullover + Yates’s Bent Row 1 set x 8-12 repetitions
Shoulder-Width Leg Press 1 set x 8-12 repetitions
Pec Deck + Weighted Dips 1 set x 8-12 repetitions
Leg Curl 1 set x 8-12 repetitions
Reverse Thick-Bar Curl 1 set x 8-12 repetitions
Seated Calf Raise 1 set x 8-12 repetitions
Manual Neck Resistance 1 set x 8-12 repetitions
Machine Crunch 1 set x 8-12 repetitions

Each set was taken to failure (i.e., reaching the point where you can no longer move the weight). He also performed every repetition with a 5/5 cadence (five seconds up, five seconds down). The “+” indicates the use of a superset.

There are some elements of Tim’s 4-Hour Body workout that I like. Training a muscle group two or three times a week, for example, generally works better than training it once a week.

But the other training methods Tim employed (slow lifting speeds and single rather than multiple sets) have not been shown to produce the kind of dramatic gains in size or strength that Ferriss is claiming.

Is It Even Possible to Gain 34 Pounds of Muscle in 28 Days?

Well, that really depends on how you define the term “muscle.”

Tim has previously described how he arrived at a Sanshou (Chinese kickboxing) contest weighing 187 pounds, dropped 22 pounds (down to 165) in time to be weighed in, before adding 28 pounds to compete the next morning at 193 pounds.

In other words, Ferriss was able to gain 28 pounds of “fat-free mass” in just 12 hours. This was done by manipulating fluid and glycogen levels in his body with the use of water, glycerol, carbohydrate and creatine.

Something else to consider is the fact that Ferriss was re-building some of the muscle he’d lost during tango training in Buenos Aires. When he started his experiment, Ferris weighed just 146 pounds, which is around 30 pounds lighter than his regular weight.

Why does this matter? A phenomenon known as “muscle memory” means that re-building lost muscle is a lot easier than gaining it in the first place.

When you take all of this into account, a 34-pound gain over 28 days doesn’t seem quite so unbelievable. But if you leave muscle memory and fluid manipulation OUT of the picture, the idea that you can gain 34 pounds of muscle in 28 days is total BS.

The vast majority of people would be doing remarkably well to gain 34 pounds of muscle in a year, let alone 28 days.