This trial for systematic reviews or meta-analyses was registered at PROSPERO as CRD42024525197 (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=525197).
If somebody wants to eliminate even more, they could try out a low carb, or even a ketogenic diet or even a zero carb diet.
Most recent studies of long term ketosis show accelerated aging markers, and some potentially harmful increases in LDL and VLDL cholesterol. Some propose periodic resets out of ketosis to avoid some of the accumulated long term issues, while taking advantage of some of the short term benefits for overall insulin sensitivity and obesity.
The human body has many, many ways to meet its nutritional needs. We’re omnivores and we have lots of anthropological history of different cultures surviving primarily on carbs, primarily on animal products, and all sorts of in between.
There are plenty of issues with people on carnivore diets, too, so I would caution against trying to swing the pendulum too far in the other direction. I’ve never seen anything suggesting that there’s a statistically significant delta between a high carb whole foods diet and a low carb whole foods diet. And even within those frameworks, it’s entirely possible that the qualitative differences between one whole food still makes a difference compared to another whole food, like the observed studies regarding red meat being bad, fatty fish being good, legumes being good, fermented vegetables being good, etc.
Nutrition science is pretty incomplete. We’re only recently learning bits and pieces about the role of the microbiome, and haven’t even finished accumulating the information we started learning in recent decades about endocrine feedback loops in nutrition and metabolism. It’ll take a lot of data and analysis to have confidence in what people are saying, and I personally take it all in with interest but skepticism.
Most recent studies of long term ketosis show accelerated aging markers
That is interesting, what study was that? What were the markers they used?
some potentially harmful increases in LDL and VLDL cholesterol
Potentially is doing a lot of heavy lifting there. The only group following keto which see a increase in LDL is the lean-mass-hyper-responder phenotype. There is some interesting research being released on this group Paper - Plaque Begets Plaque, ApoB Does Not: Longitudinal Data From the KETO-CTA Trial - 2025. However, Cholesterol is not a disease - its essential for life - the concern has never been cholesterol but atherosclerosis - if someone has elevated LDL, undamanged and unglycated (as on keto) and they are concerned they should get a CAC score so they can see their actual plaque burden.
There are plenty of issues with people on carnivore diets
I’d like to learn what those problems are, I’m currently following a carnivore diet and as far as my reading has gone there are not any downsides.
However, Cholesterol is not a disease - its essential for life - the concern has never been cholesterol but atherosclerosis - if someone has elevated LDL, undamanged and unglycated (as on keto) and they are concerned they should get a CAC score so they can see their actual plaque burden.
What you’re asking for is being studied. Here’s a meta study from 2013:
However, one established risk factor of CVD, i.e. LDL-cholesterol, still turned out to be harmfully affected by the VLC regimen, most probably attributable to the larger amounts of saturated fat in the diet(Reference Bueno, de Melo and de Oliveira1). In their discussion, the authors stated that future meta-analyses should investigate the impact of low carbohydrates (LC) v. LF on other important pathological markers, e.g. endothelial function, in order to further assess the safety of LC dietary therapies.
This is reasonable, since evidence from prospective cohort studies has shown that endothelial dysfunction represents an independent risk factor for the development of many CVD including atherosclerosis(Reference Inaba, Chen and Bergmann2). We, therefore, carried out a meta-analysis to compare the effects of LC and LF regimens on flow-mediated dilatation (FMD). FMD of the brachial artery is a non-invasive measure of endothelial function, furthermore reflecting the local bioavailability of endothelium-derived vasodilators, especially NO. Inflammation of the endothelium is regarded to play a major role in the destabilisation of atherosclerotic lesions, therefore paving the way for future CVD events(Reference Inaba, Chen and Bergmann2).
Their results:
In our meta-analysis, LC dietary protocols were associated with a significant decrease in FMD when compared with their LF counterparts. A recent meta-analysis of observational studies including a sample size of 5·547 subjects has observed that a 1 % decrease in FMD is associated with a 13 % increase in the risk of future cardiovascular events(Reference Inaba, Chen and Bergmann2)
Look, none of these studies are, standing alone, enough to really change things. But it seems to me, from the outside that you’re cherry picking your own results to justify carnivore diet.
Trying to tease out which of a million variables is truly responsible for cardiovascular health isn’t easy, but a lot of the overall trends can be seen:
Whole grains good
Whole fruit good
Red meat bad
Cured meat really bad
Seafood good
Legumes good
Now, you can quibble with confounding variables, but at a certain point trying to argue that minutiae starts looking like religious apologetics, really cherry picking examples in favor while ignoring examples against. Coming up with a coherent theory of “fiber not important” or “the foods our genetic ancestors ate are somehow bad for us now” is an uphill battle, and I’m not convinced that the carnivore diet is anything more than a scam designed to sell books.
This was a 4 week high carb, 4 week low carb group. The order was not randomized!!! Adapting to a new metabolism takes on the order of 12 weeks (from the Noakes athletic performance studies)
Here is a 12 week study https://pmc.ncbi.nlm.nih.gov/articles/PMC3845365/ Consuming a hypocaloric high fat low carbohydrate diet for 12 weeks lowers C-reactive protein, and raises serum adiponectin and high density lipoprotein-cholesterol in obese subjects
Relative to the LFHC group, the HFLC group had greater improvements in blood lipids and systemic inflammation with similar changes in body weight and composition. This small-scale study suggests that HFLC diets may be more beneficial to cardiovascular health and inflammation in free-living obese adults compared to LFHC diets.
I’ll make each of these papers a post in the keto group here and go over them in detail. This is a great set of research to dig into, thank you.
Most recent studies of long term ketosis show accelerated aging markers, and some potentially harmful increases in LDL and VLDL cholesterol. Some propose periodic resets out of ketosis to avoid some of the accumulated long term issues, while taking advantage of some of the short term benefits for overall insulin sensitivity and obesity.
The human body has many, many ways to meet its nutritional needs. We’re omnivores and we have lots of anthropological history of different cultures surviving primarily on carbs, primarily on animal products, and all sorts of in between.
There are plenty of issues with people on carnivore diets, too, so I would caution against trying to swing the pendulum too far in the other direction. I’ve never seen anything suggesting that there’s a statistically significant delta between a high carb whole foods diet and a low carb whole foods diet. And even within those frameworks, it’s entirely possible that the qualitative differences between one whole food still makes a difference compared to another whole food, like the observed studies regarding red meat being bad, fatty fish being good, legumes being good, fermented vegetables being good, etc.
Nutrition science is pretty incomplete. We’re only recently learning bits and pieces about the role of the microbiome, and haven’t even finished accumulating the information we started learning in recent decades about endocrine feedback loops in nutrition and metabolism. It’ll take a lot of data and analysis to have confidence in what people are saying, and I personally take it all in with interest but skepticism.
That is interesting, what study was that? What were the markers they used?
Potentially is doing a lot of heavy lifting there. The only group following keto which see a increase in LDL is the lean-mass-hyper-responder phenotype. There is some interesting research being released on this group Paper - Plaque Begets Plaque, ApoB Does Not: Longitudinal Data From the KETO-CTA Trial - 2025. However, Cholesterol is not a disease - its essential for life - the concern has never been cholesterol but atherosclerosis - if someone has elevated LDL, undamanged and unglycated (as on keto) and they are concerned they should get a CAC score so they can see their actual plaque burden.
I’d like to learn what those problems are, I’m currently following a carnivore diet and as far as my reading has gone there are not any downsides.
This study shows inflammatory markers are increased on a ketogenic diet: https://pmc.ncbi.nlm.nih.gov/articles/PMC6922028/
This rat study shows increased senescence in heart and kidneys in long term ketosis: https://www.science.org/doi/10.1126/sciadv.ado1463
What you’re asking for is being studied. Here’s a meta study from 2013:
Their results:
Along the same lines, here’s another study with arterial measurements that shows reduced blood flow and arterial function for those who stuck with a high protein diet: https://journals.sagepub.com/doi/10.1177/000331970005101003
Look, none of these studies are, standing alone, enough to really change things. But it seems to me, from the outside that you’re cherry picking your own results to justify carnivore diet.
The high carb versus low carb discussion is complicated and has a lot of factors at play. But the evidence for animal versus plant based low carb suggests that animal product diets are more harmful than plant product diets of similar macronutrient profiles.
Moreover, the overall trends show that those who eat a lot of whole grains (which are, by their nature, high carb plant based foods) have lower mortality than those who don’t. The same is true of those who eat a lot of fruit (again, high carb plant based food).
Trying to tease out which of a million variables is truly responsible for cardiovascular health isn’t easy, but a lot of the overall trends can be seen:
Now, you can quibble with confounding variables, but at a certain point trying to argue that minutiae starts looking like religious apologetics, really cherry picking examples in favor while ignoring examples against. Coming up with a coherent theory of “fiber not important” or “the foods our genetic ancestors ate are somehow bad for us now” is an uphill battle, and I’m not convinced that the carnivore diet is anything more than a scam designed to sell books.
Wow, great response - it’s going to take some time to read the papers and get back to you, but i’ll start here with the first study.
This was a 4 week high carb, 4 week low carb group. The order was not randomized!!! Adapting to a new metabolism takes on the order of 12 weeks (from the Noakes athletic performance studies)
Here is a 12 week study https://pmc.ncbi.nlm.nih.gov/articles/PMC3845365/ Consuming a hypocaloric high fat low carbohydrate diet for 12 weeks lowers C-reactive protein, and raises serum adiponectin and high density lipoprotein-cholesterol in obese subjects
I’ll make each of these papers a post in the keto group here and go over them in detail. This is a great set of research to dig into, thank you.