September 2025

Back to a wider variety of topics this month.

I’ve been struggling a bit with “turf toe”, which I think I picked up when a wave dumped me off a SUP board (more on that later) at Cowell Beach. As I pretty much always find to be the case, active rehab is better than total rest, a few weeks of active foot strengthening work has helped a lot and it’s motivated me to get back on my Toe Pro as well (if you’re a runner you need one of these).

WHOOP, blood pressure, and the FDA: To grossly simplify the news, WHOOP got their wrist slapped by the FDA for marketing “blood pressure insights” even after being told not to. The two are now going back and forth, somewhat publicly, in a debate that exposes some of the ambiguities and complexities of a seemingly simple question, “What is a medical device?”. There has been a lot written about how this fits into the broader discussion on wellness devices vs. regulated medical devices, if you want to dig into it I can recommend articles from Bill Betten and a series from Blythe Karow on the topic. I would add one perspective that I haven’t seen discussed a lot.

WHOOP was founded in 2012 and first raised money in 2013. To date they’ve raised about $400M over six rounds. The typical timeline for VCs to return money to their customers (LP’s, or limited partners) is about a decade. So WHOOP is getting to that point where I can easily imagine some investors are raising their voices about an IPO. CEO Will Ahmed was answering questions about a potential IPO back in 2021. The VC fund pipeline spent 4 years in a traffic jam, at least in part due to Lina Kahn leading the FTC under the Biden administration, although you can debate to what degree her policies caused the merger/IPO slowdown. Kahn was opposed to almost all tech M&A, a key source of liquidity for private market investors. And now, RFK Jr. is the first head of HHS to come out in favor of wearables as a component of making America healthier. So my pet theory is that someone on the Whoop BoD watched Super Pumped and just said “full send it” in picking a fight with the FDA, hoping for a big win to propel them to an IPO. I’m mostly joking, but corporate behavior can certainly be influenced by investor needs and in a very noisy health tech market a win like this would be worth a lot of publicity.

Moving on from my armchair musings on wearables to nutrition, I’ve often said that the problem with trying to stay lean on a vegan diet is math. Every gram of plant protein is attached to a lot of carbohydrates (or in some cases fat). So when you hit your protein goal, then tally up how many carb calories come along for the ride, you have a real challenge staying under your total calorie intake goal. You won’t have this problem if your protein comes from eggs, salmon, chicken breast, or just about any animal protein. That’s a simple analysis but the following paper gets into more detail on protein quality and you will see the same conclusion. Animal protein wins on quality. And for the umpteenth time - PEANUT BUTTER IS NOT A GOOD SOURCE OF PROTEIN. It is a good source of fat however.

Relative Energy Deficiency in Sport (REDs) has been getting more attention lately. With the high-carb fueling revolution underway, more studies coming out that rely on doubly labeled water to measure total energy expenditure, and more weekend warriors pushing their own limits, it’s great to see this awareness growing. Lionel Sanders suffered a fractured sacrum and he’s been posting a lot about REDs, low energy availability (LEA) and their relationship to bone health this summer. Here’s the first of his videos if you want to follow along with one athlete’s journey.

There’s been talk recently of “AI psychosis”, and the firestorm over the change in “personality” from GPT-4 to GPT-5 is but one example highlighting how some individuals have become emotionally attached to computer algorithms. A few of these cases have ended in tragedy. Lest we freak out over an entirely new thing, here is philosopher and guitarist Prince (RIP) warning us in 1999:

Speaking of AI, I’ve been working through Stanford’s AI in Healthcare program on Coursera. The program includes 5 classes, the first covers the basics of the healthcare system, can’t say I learned a whole lot but it was a good review. Class 2 was intro to clinical data, Class 3 covers machine learning topics, and Class 4 was Evaluation of AI in Healthcare. Overall it’s a pretty good course and worth your time if you are trying to get your hands around the use of AI in healthcare.

My super awesome GF Vicky got me into stand-up paddling, which has been on my radar a long time so it was great to finally get around to doing it. I like it because it has a few traits that distinguish it from my other training and physical activities. It’s low intensity, gets me a more varied range of motion than cycling or running, and focuses on balance. It’s also a great excuse to hang out at the beach or a lake, get a lot of sun, and generally be mellow in the outdoors. Plus my significant other likes it so it’s something we can do together. All that to say, my newsletter photos will start to include some SUP pics.