Would you ever consider putting an end to your exercise regimen and eating nothing but junk food for six months—on purpose? 

That’s what personal trainer Drew Manning decided to do in order to connect more with his clients. Manning’s year-long journey of putting on a startling 75 pounds in six months, then taking it all off and getting back into enviable shape is chronicled in his debut book, Fit2Fat2Fit: The Unexpected Lessons from Gaining and Losing 75 lbs on Purpose. To find out more, we sat down with Manning to ask him what he learned from the experience—and what you can learn too.

Myatt Murphy for Innovation for Endurance: Let’s start with the obvious: What motivates a fit guy to pack on 75 pounds in the first place?

Manning: At the start of it, I felt like I needed to do this to have a better understanding of my clients and what it was like to be overweight. Growing up fit, I never had any struggles with food addiction, or finding the motivation to go to the gym, so I figured that this experience would give me that understanding so I could help them.

MM: I know you stopped doing exercise and any calorie-burning activities, but what were you eating that raised your weight so quickly?

Manning: Before I started the journey, I would eat around 3,000 calories per day, which is a lot for most people, but in order for me to maintain the amount of muscle that I have, it’s the right amount. But while I was putting on the extra weight, I raised that amount to about 4,000 to 6,000 calories each day, with most of those calories coming from processed foods. None of the foods I ate were nutrient-dense, and most never let you feel full for very long. So each time I would eat, say, a massive bowl of a sugary cereal, an hour later, I’d be starving again.

MM: What was one of the most surprising things that happened to you while putting on the weight?

Manning: There were so many throughout the entire six months. From a physical standpoint, on the very first week, I gained 12 pounds. But it wasn’t just from the amount of calories I was eating—it was because of the types of calories I was eating. I immediately started retaining a lot more water during my fit-to-fat stage because of the highly processed foods I was consuming, such as sugary cereals, white bread, white pasta, sodas, those type of foods.

MM: When did you begin to actually feel the effects of what you were doing to yourself?

Manning: It’s interesting how quickly the visceral fat had an effect on my body. My cardio was quickly one of the first things to go. But what was unexpected was how it affected everything in my life. It made it that much more difficult to do everything, from just bending over and tying my shoes to walking up the stairs and playing with my kids. The more weight I put on, the more lethargic and lazy I became all the time because of living that sedentary lifestyle.

MM: Were you nervous about what you were doing to your body on the inside?

Manning: Certainly. On top of doing personal training, I also have a full-time job in the medical field, so I work around a lot of doctors and nurses. Even as I could see what was changing on the outside, it was what was happening on the inside that worried me the most because I knew what I was doing to my body wasn’t healthy from a medical standpoint.

MM: For example?

Manning: Well, I had doctors monitor me throughout my journey and my blood pressure got up to 167/113, which for me was very high. Also, my kidneys became like those of an alcoholic because of all the sugar that I was drinking, and I don’t drink alcohol, so who knows how many more pounds I would’ve gained if I did or how much extra stress I would’ve placed on my kidneys. So it was scary knowing what I was doing to the inside of my body from a medical and health perspective. Because looking at myself from the outside, all I could see was a change in body fat, love handles, and my belly. And being honest, that’s what most people focus on—and yet, there is so much more going on the inside that’s so much worse.

MM: What are a few of the tried-and-true innovative lessons that anyone—beginner to elite athlete—needs to remember about losing weight?

Manning: I think a lot of times we believe, in our minds, that we are in better shape than we really are. A lot of people try to rush into getting back into shape because they’re impatient or want instant results. But the truth is, it’s always better to ease your way into your exercise routine and stay patient. And don’t focus on your scale weight as a form of measurement of success.

MM: How did you avoid making that mistake when you began to exercise once again?

Manning: When I first went back to the gym, it was a very humbling experience to try to do push-ups again and have to do them on my knees. So what I did for the first month was focus on nothing but stretching and some core exercises, such as planks and side planks—and no other form of exercise. It was more important to get my eating down first because nutrition was the most important step.

MM: And after that?

Manning: After that, I had lost some weight, so that exercising wouldn’t be as stressful on my joints. When I finally went back to the gym, I never tried to do the same types of routines that I did when I was fit, which is another mistake most people make. Instead, I stuck with mostly body weight exercises, then slowly implemented lightweight exercises, and then worked my way up from there in terms of the amount of weight I was lifting.

MM: What’s the most valuable lesson you might impart to someone looking to lose weight, based on your experience?

Manning: Probably that it’s not just about the physical. It’s not just about your meal plans or how you exercise or the types of routines that you use to get in shape. All of those things are important to take the weight off, but unless you have the mental and emotional aspect down first, then no matter what you try, it will end up being just as unsuccessful as any other diet you ever tried before.

MM: So what should they do?

Manning: You need to know what challenges await you and how to overcome them when you experience them. You have to know how to overcome the emotional challenges that come with losing weight, such as plateaus and feeling judged and how to handle food addiction—those type of things. I you know how to overcome these type of mental and emotional challenges, that’s really the key to making staying fit a lifestyle.

MM: Finally, what I enjoy most about your six-month long journey of putting 75 pounds on and your six-month journey taking 75 pounds off is that it demonstrates that healthy weight loss isn’t possible within a matter of weeks, as many diet books love to claim. Was that message of “slow but steady weight loss wins the race” your biggest goal for this book? 

Manning: Absolutely. That’s where I think I differentiate from a lot of other experts and philosophies out there because I really wanted to try to get people away from that “Biggest Loser” mentality, where people are obsessed with dropping unrealistic amounts of weight in short periods of time. Most weight-loss programs are about how much weight you can lose as fast as possible.

What I really hope I’ve shown through all of this is how important it is to focus on becoming medically healthy first. The weight loss and the six-pack abs and all the other perks that people strive for—all of those things are possible—but they are really just byproducts of living that kind of healthy lifestyle. Staying healthy should always be your goal—with looking and feeling great being the icing on the cake.

—Myatt Murphy, Fitness Reporter

Fitness expert Myatt Murphy, CSCS, is the author of the best-selling books Testosterone Transformation (Rodale, 2012), The Body You Want in the Time You Have (Rodale, 2005), The Men’s Health Gym Bible (Rodale, 2006) and Men’s Health’s Ultimate Dumbbell Guide (Rodale, 2007). His work has appeared in innumerable magazines and online.

Photos courtesy of Harper Collins