How P90X made me fat—then helped me get lean

Mine isn't the typical P90X results story. It started off normally—at least judging by the “before” photos that I dutifully snapped. The photos confirmed what I already knew: I was a skinny, inactive programmer with a slowly expanding waistline.

But I was going to change all that. I'd never done anything as intense as P90X, and I just knew that following the plan would lead to some massive changes.

I threw myself into it. I set my alarm earlier every day so I could fit in the grueling, 60- to 90-minute workouts before I headed to work. I pushed myself during the workouts. I studied the nutrition guide and made changes to my diet. I started seeing my strength improve from week to week. Yay progress!

Or was it? I was getting stronger, but my primary motivation—the reason I was dragging myself out of bed every morning and busting my butt for an hour—was getting leaner. I was sick of feeling like I was on an inexorable slide towards middle-age pork. And all that hard work didn't seem like it was putting a dent in my mid-section.

In fact—is it possible?—it seemed like I was packing on fat. After a few weeks it was clear that I was gaining weight, but I told myself that it might be muscle weight. But my waist measurement was increasing as well. Frustration started to set in.

By the end of the second month, it was obvious that I was on the wrong track. I'd gained 6 or 7 pounds, and my waist measurement had increased by more than 1 inch. Worse, I was mentally exhausted and fighting some nagging injuries.

I decided to quit.

Dropping out of P90X was undoubtedly the low point for me in my physical fitness experience. I felt like a failure—I'd believed the program would help me finally turn things around, to take control of a body that never seemed to respond to any of my efforts at training or dieting. But I couldn't hack it. I spent a few days wallowing in my defeat. Or possibly it was weeks, I don't remember. Dark times.

As I started to recover, though, two things happened. The motivation that drove me to P90X—my desire to finally take charge of my physical well being—that motivation returned, stronger than ever. Previously, I'd wanted to get in better shape, but I wasn't willing to really work at it. Now I realized that it was going to take some serious work, and I was ready to put in the effort.

And secondly, a little time bomb went off in the back of my mind. Something I'd read in the P90X nutrition guide came back to me. I don't remember the exact wording, but it went something like this: “Eighty percent of your results from this program will come from your diet.”

Record scratch. Wait, wat?

The implications of that little claim floored me. So I'd spent every morning for two months killing myself—and it was only supposed to make a 20 percent difference at best? It was almost like the exercise plan in the P90X program was a placebo designed to get you to buy in to eating better.

If diet was that important, it explained my failure. I didn't make the mistake of ignoring the P90X diet plan entirely and just eating pizza and donuts. No, I gave it a good effort. Trouble was, the plan called for me to eat more than I'd been eating prior to starting P90X. A lot more—I was eating at least 25 percent more calories. Had to fuel those crazy workouts! But instead of helping me build massive guns, all those extra calories went straight to my midsection.

When I had some mental distance between me and the P90X madness, I saw clearly where things broke down. It's such a complicated program, and there's so much emphasis on the workouts, that I hadn't had much mental energy left to troubleshoot my diet.

The path forward was clear: Focus on the 80 percent. Rather than launching into another intense training regimen, I was determined to figure out how to eat in such a way that I could lean out without vomit-inducing workouts. Whatever it took—eating the same boring meals over and over? Weighing out food portions? Giving up my favorite treats?—seemed like a small price to pay if I didn't have to spend an hour plus every day working out.

It took some time, but it worked. This weekend I'm ending my year-long quest nearly 27 pounds lighter than my post-P90X peak. I've lost 6 inches off my waistline.

But more importantly, I understand better how my body works and how to drop fat when I want to.

To celebrate, I'm buying a couple of pairs of 30-inch jeans and planning an epic cheat day—I'll be living on apple crisp and chicken wings for 24 hours, thank you very much.

Then on Sunday, I start right into the next phase of my adventure. Can I finally put some muscle on this skinny body?

I've failed in the past, but this time I have a fighting chance.