I continue to be blown away by all of the kind feedback about the show - thanks everyone!
One topic that arose over on Facebook deserves mention here. On the podcast I joked that pro cyclists “eat like we’re trying to give ourselves diabetes” in context of our discussion about the importance of carbohydrates (CHO). The last thing I want to do is spread misinformation, so I want to clarify that I did not meant to say CHO causes diabetes! Instead, I was referring to the fact that high level endurance athletes ingest a lot of simple sugars to fuel their training, which without the insulin sensitizing effects of exercise, would likely cause repeated insulin spikes that over time could lead to insulin resistance (IR), which is a precursor to prediabetes and Type 2 diabetes (T2D). I apologize for the lack of clarity and context and definitely meant no offense!
Someone commented that intramyocellular lipids (small droplets of fat in muscle cells) cause T2D and cited a website that claims to ground recommendations peer-reviewed science. I wrote the following response and thought it would be a good thing to share here, because it illustrates some of the common pitfalls of allowing an so-called expert to cherry-pick and summarize primary sources without verifying those conclusions for yourself (even if that person has an M.D.). For the record, I am aware of the irony that I am “picking” sources to make a point here, as well, but my point is that you should take all perspectives - mine included - with a big grain of salt!
Here is my response; you can see the full comment thread on the Trainer Road FB page:
I appreciate your interest in this topic. Let’s dig into it. Intramyocellular lipids (IMCL) have been CORRELATED with insulin resistance (IR), i.e. we do see higher IMCL in people with IR, but whether IMCL CAUSE IR has not been proven and remains controversial. An example of this is the Athlete’s Paradox - see, e.g., this 2018 study Dissociation of intramyocellular lipid storage and insulin resistance in trained athletes and type 2 diabetes patients; involvement of perilipin 5? - PubMed – where athletes have the same high levels of IMCL as non-trained people with Type 2 Diabetes (T2D), but the athletes do not have T2D or IR—evidence contrary to Dr. Greger’s assertion that IMCL cause IR & T2D. More here: Exercise-induced alterations in intramyocellular lipids and insulin resistance: the athlete’s paradox revisited - PMC. The reality is far more complex. Dr. Greger is cherry-picking studies (most from 20 years ago) to support his assertion that a vegan diet can reverse/prevent various diseases, including T2D. He doesn’t mention any of the many (more recent) studies showing that a high-fat low-carb diet can also treat T2D by increasing insulin sensitivity. I found three in a brief search, including a comprehensive review article:
Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets - PMC,
The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus - PMC,
An Online Intervention Comparing a Very Low-Carbohydrate Ketogenic Diet and Lifestyle Recommendations Versus a Plate Method Diet in Overweight Individuals With Type 2 Diabetes: A Randomized Controlled Trial - PMC .
I have nothing against veganism (it has many benefits and helps a lot of people), but I do have a problem with selectively using science to justify false claims. Eating vegan is beneficial for many people and may work for you, but the truth is there is no silver bullet that works for everyone. (The closest thing we’ve got to a silver bullet is exercise, and even that doesn’t cure everything.) Anyone who tells you that all you have to do is follow this ONE diet and you can reverse all major diseases is selling you something, and in fact, Dr. Greger is doing just that.
With all of that said, if it works for you, that’s great! Physiology is highly individual and varied, so I encourage everyone to experiment to find what works best for them. Just because one study found a particular result does not mean that it works for all of humankind, or that the study’s results can even be replicated (see Why Most Published Research Findings Are False). That’s why it’s important to read multiple studies and look for counterexamples to prevent confirmation bias. Dr. Greger is not portraying a balanced view of our current understanding of metabolic disease and instead speaks in absolutes and presents only self-confirming evidence.
I write and edit scientific research proposals for a living, have authored/published peer-reviewed journal articles on physiology, and have studied human (and in particular exercise) physiology for many years with the world’s leading experts, and I still tell people to take what I say with a grain of salt and figure out what works for them. Anyone who doesn’t is not a real scientist. Science doesn’t work in absolutes, especially when it comes to physiology. In fact, just to check myself, I reached out to a physiologist friend who studied metabolic disease at the Mayo Clinic, and he said: “The real issue is not a matter of simple [IMCL]. Metabolic flux, tissue redox balance, and intramuscular inflammation all play a role in insulin resistance.” Even he is quick to point out the gray area.
The last thing I want to do is spread misinformation. I want to reiterate that I didn’t say carbohydrate causes diabetes, but I should have better clarified my comment, given the context of the conversation. I also don’t assert that sugar CAUSES diabetes (see my previous comment), but rather that repeated insulin spikes over time can lead to insulin resistance (IR). This is clearly not the only pathway to IR, nor does it capture the complexity of metabolic disruption that leads to T2D.
If you genuinely want to understand the science, I strongly encourage you not to take Dr. Greger’s word at face value and instead to go to the original literature and see for yourself. You can look up the original sources for studies he cites, or search keywords for related studies here: PubMed
You’ll quickly see a range of perspectives and far more complexity than what he portrays. I’ve seen worse and more harmful diet advice out there, but the fact remains that he does not offer his viewers an accurate representation of the state of the science on nutrition.
I realize I probably won’t change your mind about Dr. Greger or his website, but I hope that anyone else reading this thread will think twice about the nutritional “science” offered by websites that offer silver-bullet diets (and books and DVDs and related products). Just because his site operates as a non-profit does not mean that he isn’t making money from it (he owns the site according to public records and his non-profit reported over 1.5 million dollars in 2017 income according to Charity Navigator). As for veganism, there are plenty of sound reasons to promote this lifestyle without resorting to cherry-picking data to construct misleading conclusions.