More on Cystatin C & Kidney Fx
Most of what is available to read about kidney function concentrates on people with CKD. I’d love to hear more about the various lab values for determining kidney fx, how healthy peoples’ values may be erroneous with “usual” testing and your strategy for following kidney dx over time with Cystatin C. Basically, I’d love to hear a whole AMA episode on all things kidney. Context: I’ve had four patients recently that all tested in the 50s for GFR based on Cr but when retested based on Cystatin C had a GFR over 100. This seems like a big discrepancy!
Available self-tests to estimate VO2 Max?
You advocate using RPE (rating perceived exertion) to approximate Level 2 aerobic level vs formal watt meter mets or lactate testing.Yet for VO2 Max I have only heard you suggest formal testing in an exercise physiology lab. This is less widely available, can be difficult to schedule and is certainly difficult to do! I have heard there are some self-tests that are said to correlate with VO2max. Such as timed walk or run tests over a set distance, or a cycle/treadmill measurement of wattage vs time at specific heart rate zones (anaerobic threshold or maximal). Are there any self-administered tests one can do to be a proxy for VO2max?
Thermodynamics and calories in versus out--why does everyone use this argument?
I recently saw a clip of you chatting with Biolayne about the calories in/out studies when comparing low-carb and low-fat diets and essentially debunking any differences between the two. A lot of folks seem to fall back on the overly simplistic "it's thermodynamics..." "you can't argue with physics" arguments that have a clickbaity feeling to them. My question is, why does everyone think bodily function can be so simply compared to burning fuel in a furnace when everything I've seen from a biological standpoint references ATP as the fuel source for cellular function, and how carbs, vs fat, vs glucose at their various states all find their way being converted to ATP through very different mechanisms--which would seem to reason could easily alter the amount of energy the body consumes on their own. Is it possible that the majority of studies comparing the two diets are focused too much on dieting in general in which case the restricted caloric intake in both situations is not great enough to see a difference between the energy expenditure truly? Have any studies compared macronutrient intake with excessive caloric consumption, say 5,000+ calories per day? Perhaps a more fundamental question that might frame this better is to what degree is our daily resting metabolism based on the processes of converting energy versus using it? Is it possible that when measuring macronutrients at a caloric level, they do equate to a similar quantity of ATP with all conversions being taken into account?