In this podcast, I chat with scientist and friend Dr. Bill Campbell all about flexible dieting. Specifically, we discuss a study out of his lab that compared a flexible, IIFYM diet with a more rigid, meal plan approach.
In case you’re not familiar with Dr. Campbell, he’s a professor of Exercise Science and the Director of the Performance & Physique Enhancement Laboratory at the University of South Florida, who’s also published more than 150 scientific papers.
In other words, Dr. Campbell has long been behind the scenes, conducting research on practical, fitness-related matters that can be applied to get us more jacked.
The study we’re discussing on flexible versus rigid dieting is no exception. Surprisingly, it’s the first comparison of IIFYM to rigid dieting with resistance-trained athletes as the subjects, which makes it especially applicable to fitness folks.
In this episode, Dr. Campbell describes the study, the results, and his practical approach of protein-anchored flexible dieting. We also get into incorporating processed versus unprocessed foods in a flexible diet, fiber supplementation, post-diet weight regain, animal versus plant proteins, circadian rhythms, and a lot more.
So, if you want to learn what the science says about flexible dieting and how it compares to following a meal plan, how processed food affects our eating habits, and how to avoid body fat overshoot after your diet, don’t miss this episode!

Timestamps
0:00 - My pre-workout Pulse’s seasonal flavors Frosted Cranberry and Apple Cider are 20% off this week only! Go to buylegion.com/pulse to check them out and use coupon code MUSCLE to save 20% on any non-sale items or get double reward points!
4:25 - Tell us about your findings on the study of flexible vs. rigid dieting.
10:47 - Would you expect the same results if someone was new to dieting?
19:02 - Will you experience more hunger if you lose more muscle while dieting?
24:05 - How much fat can I gain in one day?
25:10 - When is it appropriate to take a rigid approach vs taking a flexible approach?
30:36 -  How do we choose the right foods to hit our macros?
42:10 - What is your theory on eating around your circadian rhythm?
49:45 - What are your thoughts on supplementing with fiber?
52:20 - Is there anything else you would like to add?
53:41 - What is the best source of protein?
57:51 - Where can we find you and work?

Mentioned on the Show:
My pre-workout Pulse’s seasonal flavors Frosted Cranberry and Apple Cider are 20% off this week only! Go to buylegion.com/pulse to check them out and use coupon code MUSCLE to save 20% on any non-sale items or get double reward points!
Bill Campbell’s Instagram: https://www.instagram.com/billcampbellphd/