Metabolism, energy balance, and aging: How diet, calorie restriction, and macronutrients influence longevity and metabolic health | Eric Ravussin, Ph.D.

**Peter Attia, MD** (0:11)
Hey everyone, welcome to the Drive podcast. I'm your host, Peter Attia. This podcast, my website, and my weekly newsletter all focus on the goal of translating the science of longevity into something accessible for everyone. Our goal is to provide the best content in health and wellness, and we've established a great team of analysts to make this happen. It is extremely important to me to provide all of this content without relying on paid ads. To do this, our work is made entirely possible by our members, and in return, we offer exclusive member-only content and benefits above and beyond what is available for free. If you want to take your knowledge of this space to the next level, it's our goal to ensure members get back much more than the price of the subscription. If you want to learn more about the benefits of our premium membership, head over to peterattiamd.com/subscribe. My guest this week is Eric Ravussin. Eric is the Director of the Nutrition Obesity Research Center at Louisiana State University's Pennington Biomedical Research Center, where he also serves as the Douglas L. Gordon Chair in Diabetes and Metabolism. Having published over 600 peer-reviewed manuscripts, Eric is regarded as a world expert in obesity, metabolism and aging and has received numerous awards for his contributions to these fields. As discussed at the beginning of this podcast, Eric and I worked together for about four years, roughly 15 years ago. And during that period of time, I just came to have such an admiration for Eric, his curiosity and his intellect when it comes to this field. We talk about Eric's background and his extensive experience in metabolic research, in particular when it comes to measuring energy expenditure, which turns out to be a very technically demanding problem. We go through the various methods that this has done, including what is today regarded as the gold standard. This of course is necessary because if you want to understand energy balance, you must clearly be able to measure energy expenditure. We of course discuss energy balance, energy expenditure and food intake, how we regulate appetite, and the findings of a very important study that Eric did, which look at the impact of manipulating the ratio of macronutrients to see if it would indeed change energy expenditure. Disclosure, I was involved in the funding of that study. We then delve into the calorie study, which looked at caloric restriction and discuss its insights as it pertains to the biomarkers of both primary and secondary aging. We speak about the implications of GLP-1 agonists and similar drugs in replicating the benefits of caloric restriction and look to the future of this research and see how new technology advancements like AI might come into play. So without further delay, please enjoy my conversation with Dr. Eric Ravussin.
Well, Eric, thank you so much for joining me. Sorry that we can't be in person, but given that you're in the south of France and I'm over here in Texas, that would have made it pretty difficult because normally we're quite a bit closer. You're obviously in Louisiana. But anyway, it's wonderful to see you again. It has been close to 10 years, right?

**Eric Ravussin** (3:18)
I think so. I think so. But I have found memories of our interactions.

**Peter Attia, MD** (3:24)
Yes, as do I. I guess by way of background, maybe we can even just give people a bit of a sense of how closely we did work together for four years. At the time, I was part of an organization called NUSI, and you were one of the six principal investigators for what was a very audacious experiment and part of something called the Energy Balance Consortium along with Kevin Hall, Steve Smith, Rudy Liebel, Mike Rosenbaum, and who am I missing? Mark Reitman. And nevertheless, this was a once in a lifetime opportunity to do something that had never been done before, which was a multi-center indirect calorimetry inpatient study that was really aimed at trying to at least pilot what would be necessary to do the definitive experiment to answer a question that I'm sure we're going to talk about a lot today, which has to do with the nature of calories and weight gain. So I will leave it at that only by way of background to say that we had the incredible pleasure of working together and really getting into the weeds of how one technically tries to measure these things and how difficult it is on all of the challenges and potential pitfalls of this. But let's just take a step back and maybe give folks a sense of your life's work and your life's passion. You've been the head of Pennington Biomedical Research for how many years now? Is it 20 years?