“Jim Stoppani Explains” Episode 2: Protein and Intermittent Fasting

Dr. Stoppani is back to share the benefits of intermittent fasting and the differences between casein and whey proteins.

BarBend and Generation Iron‘s weekly interview series with author, exercise physiologist, and creator of JYM Supplement Science Dr. Jim Stoppani debuted on Feb. 21, 2021. In the series premiere, Stoppani broke down what contralateral training and pre-exhaust training are and why they are effective.

In episode two, the interview continues with moderator Vlad Yudin questioning Dr. Stoppani about the science behind nutrition and its yearly evolution. He specifically dives into the benefits of intermittent fasting and the differences between whey protein and casein protein. Check out part two of the interview with Dr. Stoppani below, courtesy of Generation Iron‘s YouTube channel:

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Science of Nutrition

Yudin opens part two, asking if more is actually learned about nutrition each year through new studies or if the knowledge gained is primarily “the same concept” as previously known information. The immediate response by Dr. Stoppani:

We’re always learning. That’s the great thing about science.

Stoppani used an example from when he was the Senior Science Editor at Muscle & Fitness — he and “all of us, every research scientist out there” advocates not to consume casein protein around one’s workout because it was absorbed too slowly. Something like whey protein was faster digesting and thought to be better. However, science has shown that casein effectively maintains muscle-protein synthesis for a more extended period of time. (1)

While researching Yale University, Dr. Stoppani was part of a research team that debunked the long-standing belief that fasting slowed metabolism. Research showed that the opposite is true — fasting boosts metabolism, with reduced body mass “almost entirely due to fat loss.” Stoppani is convinced of the health benefits that intermittent fasting provides. In addition to the metabolic benefits, Stoppani claimed intermittent fasting creates better glucose disposal, decreasing the risk of type II diabetes and improving immune function. (2)(3)(4)

Stoppani dives deeper into the different kinds of protein and the differences between whey and casein. Whey is soluble, meaning faster digesting than casein. Casein molecules are layered, and enzymes in the stomach break down each layer. That process of digestion takes longer, upwards of approximately seven hours, according to Stoppani.


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Keep Watching

Episodes in this interview series will release on subsequent Mondays on Generation Iron‘s YouTube channel. Episode three’s scheduled release date is Monday, March. 7, 2022.


  1. TIPTON, K., ELLIOTT, T., CREE, M., WOLF, S., SANFORD, A., & WOLFE, R. (2004). Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise. Medicine & Science In Sports & Exercise, 2073-2081. doi: 10.1249/01.mss.0000147582.99810.c5
  2. Templeman, I., Smith, H., Chowdhury, E., Chen, Y., Carroll, H., & Johnson-Bonson, D. et al. (2021). A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults. Science Translational Medicine13(598). doi: 10.1126/scitranslmed.abd8034
  3. Hannan, M., Rahman, M., Rahman, M., Sohag, A., Dash, R., & Hossain, K. et al. (2020). Intermittent fasting, a possible priming tool for host defense against SARS-CoV-2 infection: Crosstalk among calorie restriction, autophagy and immune response. Immunology Letters226, 38-45. doi: 10.1016/j.imlet.2020.07.001
  4. Albosta, M., & Bakke, J. (2021). Intermittent fasting: is there a role in the treatment of diabetes? A review of the literature and guide for primary care physicians. Clinical Diabetes And Endocrinology7(1). doi: 10.1186/s40842-020-00116-1

Featured image: @jimstoppani on Instagram