Bill Campbell PhD: Physique Research, Diet Breaks and More!

If you’re in the world of physique competition, a physique Coach, or just wanting to look great naked then Bill Campbell, PhD, is on the cutting edge of research and the Professor you need to know! We spoke recently covering everything from how he got into the science of physique enhancement, to Diet ReFeeds, Diet Breaks, and extreme fat loss. We all have a lot to learn from Bill so let’s dive right in:

Q – Hi Bill, first off thank you for all that you do for our industry, enhancing our understanding of how the human body responds to diet and exercise, and the extra time you spend translating research for the masses. What got you into the industry, and in particular fat loss and muscle building research?

Bill – Thank you for having me and helping me share that. What got me into the industry…

Bodybuilding! When I was a sophomore in college (about 20 years old), I became obsessed with lifting weights, taking supplements, and wanting to build my body. Over time, I realized that the greatest impact I could have on the fitness profession was from the academic side — by contributing to the scientific literature on the best practices for building muscle and losing body fat.

Q – Are there any interesting studies you’re working on right now that you can share with us?

Bill – My research team just started working on a systematic review and meta-analysis which will compare resistance training vs. aerobic training and which is best for maximizing fat loss. In addition, we are looking at what happens to fat loss when you combine these two modes of exercise (concurrent training). We are early in this process, so I don’t have any results to share yet!

Q – Can you share an impactful piece of research? What practical recommendations would you draw from it?

Bill – The most impactful research study/paper that my research group published was the work we did on Diet ReFeeds (PMID = 33467235). What we observed in this study was that when resistance trained males and females took a break from their diet every weekend, they were better able to maintain their muscle mass as compared to the group who did not take any Diet Refeeds during the study.

The practical recommendation that you can take away from this study is that it’s ok to increase your calories (back to maintenance calories) on the weekends during a diet and you don’t have to worry that it will sabotage your fat loss success.

By the way, this study is freely available to read here: Intermittent Energy Restriction Attenuates the Loss of Fat Free Mass in Resistance Trained Individuals. A Randomized Controlled Trial.

Q – Tell us about your research review service and why you started it?

Bill – It is called ‘Body by Science’ and it is a monthly research review where I summarize 2 research studies that solely focus on either fat loss or muscle gain. I break down 2 studies each month in a way that is easily understandable to anyone that is serious about their exercise and nutrition programming. You don’t have to be a researcher or have a PhD to understand the research studies that I summarize — my job is to break them down so that each study is easily understandable. In addition to my summary of each study, I also bring in two experts each month (one male and one female) to help us APPLY the research findings.

Reading research and understanding the results is not enough. We have to be able to apply the research into the lives of real people and having experts give us some ideas for applying the research is what I believe provides the most value in my ‘Body by Science’ research review.

Lean more about the Body by Science research review here

Q – What’s the biggest mistake you see physique athletes make when cutting for competition, or trying to get photoshoot lean?

Bill – Not giving themselves enough time for the process. When this happens, it forces them to take a more aggressive approach to lose the amount of body fat that is required to have a ‘shredded’ look, but when this process is rushed, unfortunately it sets up an environment where much more lean muscle mass is lost in the process that is necessary.

One other mistake that I see a lot of novices make is having unrealistic expectations. It is common to for a novice physique athlete or someone trying to get lean for a photoshoot to have an unrealistic picture of what their physique will look like at the end of their contest preparation (or photo shoot date). What they fail to realize is that the bodybuilders and fitness models that they look up to and want to look like are often very experiences dieters and have many years of trial and error that has allowed them to dial in their conditioning for these milestones.

Your first bodybuilding show or your first photoshoot will not be your best one!

Q – Is there a certain level of caloric deficit you’d recommend when trying to lose body fat?

(For example a female physique athlete cutting for competition over 12-20 weeks. Starting at 150lbs where stage weight somewhere around 130lbs.)

Bill – My research lab has done multiple studies in resistance trained individuals and what we have found to work extremely well for causing nearly all of the weight loss to come from body fat stores (and maintain nearly all muscle mass during a diet) is a 25% caloric reduction that is paired with resistance training and a relatively high protein diet.

For a physique athlete, it may be necessary to be a little more aggressive than this, such as a 30% caloric deficit. For others, if there is no competition or landmark to aim for then a more modest caloric deficit may even be better—such as a 20% caloric deficit.

Q – I’ve heard you speak a number of times about the concept of diet breaks. Please give us a brief into and share with us what your research has found?

Bill – A Diet Break is exactly what it sounds like—taking a break from your diet! It’s where you eat at your maintenance calories for a certain period of time, generally 1-2 weeks.

As an example, let’s say someone plans to go on a diet for 2 months (8 total weeks). A traditional diet would be continuous in nature, and the dieter would simply diet for 2 consecutive months without every taking a break from being in a caloric deficit.

Implementing a diet break strategy would look a little different. Instead of dieting for 8 straight weeks, the dieter may initially diet for 4 weeks and then take a 2-week diet break where they go back to maintenance calories. After the 2-week diet break, they then go back on their diet for an additional 4 weeks. It’s important to understand that adding in a few weeks of diet breaks does add more total time to the dieting process. In this example, the person who chooses to diet for 8 weeks but includes a 2-week diet break has extended the entire diet process to 10 weeks as compared to 8 weeks for the traditional diet. This is one of the primary criticisms of diet breaks—they add time to reach your weight loss goals.

What are the potential benefits if implementing diet breaks?

To answer this question, we first must appreciate the negative consequences of dieting.

Dieting, especially crash diets that extend for long periods, invite adverse events, including:

  • A suppressed metabolism
  • Loss of muscle mass
  • Weight loss plateaus (making future fat loss more difficult)
  • Increased hunger (which in my case also increases my irritability!)

In the most favorable light possible, diet breaks alleviate these negative outcomes. In theory, an effective diet break will prevent your metabolism from crashing during an extended diet, which parlays into eliminating weight loss plateaus. Further, an effective diet break will help to preserve muscle mass since calories are increased for short periods of time, creating an anabolic environment for maintaining muscle mass.

A landmark study on diet breaks (called the ‘Matador Study’) got everyone excited about diet breaks because of how effective they appeared to be. The Matador study reported significantly greater weight and fat loss in subjects incorporating diet breaks. In addition, the subjects incorporating diet breaks were also able to preserve their metabolic rates better than the subjects that never took a break from their diet. With results like this, you can see why diet breaks became very popular!

It’s important to note the Matador study was conducted in sedentary, obese males. How effective are diet breaks in fit people who resistance train? Until recently, there was no data in resistance trained people so the best we could do was hypothesize.

In the past 2 years, there have been 2 studies on Diet Breaks in resistance trained people (an Australian study and my lab’s study in resistance trained females). In both studies, incorporating diet breaks did not cause more fat loss or cause a greater amount of muscle mass to be retained. From that sense, it appears that the Diet Breaks did not offer any advantage to the resistance training dieters (but it also did not cause any harm or sabotage their fat loss efforts).

The one thing that both studies did report was that the Diet Breaks caused favorable outcomes related to hunger. The groups of resistance trained subjects that incorporated diet breaks had less hunger, a lower drive to eat, and were less likely to overeat when stressed or in the presence of food.

Both studies reported similar findings in this regard!

The thing that makes people fail while dieting is they lose the temptation to hunger and they overeat. Based on this early research, it appears that diet breaks help curtail hunger and the propensity to overeat and I believe that if a diet or fat loss phase is extended for long periods of time, that the utility of a Diet Break becomes more and more valuable.

Q – What’s one thing you used to believe that you’ve changed your opinion on with regards to physique training/dieting?

Bill – I used to believe that you always had to take a conservative approach to fat loss. Never should you be aggressive with your dieting (caloric deficit) as when you reduce your calories too much it will result in a loss of muscle mass and subsequently this will result in a suppressed metabolism which makes further fat loss much more difficult and places the dieter in a situation in which they are more likely to gain significant amounts of body fat when the diet is over.

While all of these negative consequences of crash dieting are likely to happen, I have changed my opinion on how an aggressive diet may be beneficial.

What I have come to realize is that you can be aggressive during a diet and induce quite a bit of fat loss and preserve your muscle mass as long as one thing is followed—the duration of the aggressive calorie-restriction is short-lived.

For example, we had resistance trained males and females reduce their calories by nearly 40% for a 2-week period. During this 2-week aggressive fat loss phase, they continued to resistance train and consume higher amounts of protein (1 gram/pound bodyweight or 2.2 grams/kg bodyweight).

At the end of the 2-week aggressive diet phase, they were able to maintain their lean mass and lose nearly 100% of all weight loss from body fat stores.

I still have the opinion that an aggressive diet is not a good approach for long-term fat loss success. However, if an aggressive diet is followed for a very short period of time (no more than 2-weeks), and if this strategy is coupled with high protein intake and resistance training, the typical adverse effects of this approach causing large losses of muscle mass can be prevented.

Related: How to get beach body lean in an emergency (featuring Bill Campbell)

Q – Finally, what does Bill eat in a day when trying to lose body fat? Do you practice what you preach?

My approach to dieting is a protein-anchored flexible dieting approach. What this means is that my diet is set up as follows:

  1. Determine the number of calories that I will be consuming that will induce fat loss
  2. After total calories are set, I aim to get about 1 gram of protein per pound of bodyweight
  3. For my remaining calories, I am guided by my preferences. If I want to have foods that are higher in carbs on a certain day (such as oats or rice-centric meals), I’ll do that. If I want to have foods that are higher in fats on another day (such as bacon or beef), I’ll do that.

Now that I shared the framework for my diet, the types of foods that I will typically consume are these:

  • First meal: Protein bar and protein shake
  • Second meal: rice with chicken (or a chicken burrito with Mexican rice and black beans)
  • Post-Workout: 1-2 scoops of whey protein
  • Third Meal: Whatever my wife cooks for dinner (or a fruit smoothie with added protein)
  • Nighttime snack: Depends on my remaining macros for the day. If I need more protein, I’ll have another protein shake or protein bar. Other times I’ll have a bowl of ice cream or a serving of baked potato chips.

The one thing that I WISH I did a better job of is eating more vegetables. I don’t like vegetables! One thing I’ve done recently to help with this is make a home-made vegetable soup. I find it much easier to sip on hot vegetable soup than to eat the vegetables as whole foods!

Lean more about Bill Campbell’s and the Body By Science research review HERE

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