Inside Sports Nutrition

Your physiology doesn't always follow what the textbooks say. In this episode, we sit down with Dr. Marco Altini (ultra runner, endurance coach, data scientist, and thinker at the intersection of physiology, technology, and performance). Marco opens up about the moment he realized that doing the same high-carb diet he recommended to himself for years wasn’t actually working as well as he thought. He walks us through how shifting to a periodized approach - changing fueling based on training demands rather than sticking to a fixed carb ratio - improved his fat oxidation, gut health, and performance markers in ways he hadn’t seen before. Marco grounds the discussion in real data, including how his substrate oxidation changed after adjusting his diet and why better metabolic flexibility matters for endurance athletes. Along the way, we tackle common misconceptions about high-carb diets, the link between GI distress and fueling strategy, and why testing beats guessing when you want to understand your own response to food and training.What we cover in this episode:Why metabolic efficiency is not a single target, but a moving rangeHow nutrition periodization can support training without wrecking your gutThe overlooked connection between GI distress and everyday dietary patternsWhat Marco learned from tracking substrate oxidation instead of guessingHow fat oxidation and VO₂-related metrics can change with nutrition shiftsWhy weight loss is not the same thing as improved performanceThe role of testing in understanding what your body actually responds toHow to think critically about fueling without copying elite or influencer strategiesLinks:Follow Dr. Altini's Substack and find him on Instagram @altini_marcoMarco's Substack article "Periodized Nutrition and Metabolic Flexbility for Endurance Performance"Marco's Substack article "Learnings from a Year of Periodized Nutrition and Metabolic Testing"Bob's Metabolic Efficiency Training book (3rd edition)More about our guest: Marco holds a PhD cum laude in applied machine learning, a M.Sc. cum laude in computer science engineering, and a M.Sc. cum laude in human movement sciences and high-performance coaching. He has published more than 50 papers and patents at the intersection between physiology, health, technology and human performance. He is the co-founder of HRV4Training, Endurance Coach at Destination Unknown, advisor at Oura, guest lecturer at VU Amsterdam, and editor of the Wearables department of IEEE Pervasive Computing. He loves running.Download the Patreon app to join our free Community (@isnpodcast) and become a supporter of the show by joining our low-cost Silver or Gold level membership. -------Subscribe to our show to get the weekly episodes and also check out the YouTube channel.You can help us remain 100% ad-free and get access to exclusive bonus content and behind-the-scenes conversations with Bob and Dina. Join our Patreon community or find us in the Patreon app by searching ISNPodcast.We’d love to connect with you on Instagram @isnpodcast and on Facebook @insidesportsnutrition And when you’re ready to level up your health and performance even more, check out the services offered by Bob and Dina at their respective businesses.

In this last episode of 2025, we provide our top 2 recommendations for what to do in 2026. -------Subscribe to our show to get the weekly episodes and also check out our YouTube channel.You can help us remain 100% ad-free and get access to exclusive bonus content and behind-the-scenes conversations with Bob and Dina. Join our Patreon community or find us in the Patreon app by searching ISNPodcast.We’d love to connect with you on Instagram @isnpodcast and on Facebook @insidesportsnutrition And when you’re ready to level up your health and performance even more, check out the services offered by Bob and Dina at their respective businesses.

Are PRMs just another trendy supplement, or are they doing something fundamentally different? In this episode, we do a quick overview of Pro Resolving Mediator supplements, how they differ from fish oil, and why resolving inflammation is not the same as suppressing it. Tune in to learn more! What are your questions about PRM supplements? Let us know over in our free Patreon Community (@isnpodcast).  -------Subscribe to our show to get the weekly episodes and also check out our YouTube channel.You can help us remain 100% ad-free and get access to exclusive bonus content and behind-the-scenes conversations with Bob and Dina. Join our Patreon community or find us in the Patreon app by searching ISNPodcast.We’d love to connect with you on Instagram @isnpodcast and on Facebook @insidesportsnutrition And when you’re ready to level up your health and performance even more, check out the services offered by Bob and Dina at their respective businesses.

If you’ve seen the growing wave of menopause supplements and felt unsure what to make of them, you’re not alone. In this Under the Microscope episode, Dina and Bob review a few products targeted towards menopause and discuss ingredient profiles, quality, safety, and marketing tactics being used in this supplement category. The episode is designed to help you cut through the noise and encourage you to evaluate supplements more carefully so you can decide what’s worth your attention and what is not worth your money.What are your questions menopause supplements? Let us know over in our free Patreon Community (@isnpodcast).  -------Subscribe to our show to get the weekly episodes and also check out our YouTube channel.You can help us remain 100% ad-free and get access to exclusive bonus content and behind-the-scenes conversations with Bob and Dina. Join our Patreon community or find us in the Patreon app by searching ISNPodcast.We’d love to connect with you on Instagram @isnpodcast and on Facebook @insidesportsnutrition And when you’re ready to level up your health and performance even more, check out the services offered by Bob and Dina at their respective businesses.

In this episode, Dina and Bob talk through a recent Triathlete magazine article outlining how some of the top professional athletes fueled at the Ironman World Championships in Nice and Kona this year. We review the carbohydrate intake ranges along with the fluid and sodium data and add context for what may explain the differences among the pros and why these strategies don’t always translate to age-group competition.Links:Article from Triathlete.com: An Analysis of Ironman World Championship Pros' High-Carb Nutrition Plans What are your questions about high carb fueling? Let us know over in our free Patreon Community (@isnpodcast).  -------Subscribe to our show to get the weekly episodes and also check out our YouTube channel.You can help us remain 100% ad-free and get access to exclusive bonus content and behind-the-scenes conversations with Bob and Dina. Join our Patreon community or find us in the Patreon app by searching ISNPodcast.We’d love to connect with you on Instagram @isnpodcast and on Facebook @insidesportsnutrition And when you’re ready to level up your health and performance even more, check out the services offered by Bob and Dina at their respective businesses.