Nov 04

#KetoAF Experiment Results – Trialing High Fat Carnivore

#KetoAF Talk of the Town on Twitter

Around March of this year I began to hear the term “#KetoAF” being used on Twitter. Not just from one person, but from several. The people using the hashtag weren’t using it to mean “very keto” or to exclaim that something was keto in a cool way. Instead, they were using it as a shorthand for “Keto Animal Foods”, or a carnivorous diet where fat was prioritized.

The people discussing KetoAF were also talking about how it helped kickstart weight loss after long stalls, or helped to resolve persisting issues that were lingering even with a more protein heavy carnivorous diet. I was intrigued, especially as I had heard the Paleolithic Ketogenic diet (PKD) discussed at CarnivoryCon earlier that same month.

By April, I was making plans and coordinating with Amber O’Hearn (who coined the term KetoAF) and Josh Blackburn (a fellow KetoAFer) to set up the experiment. This would turn out to be one of the longer experiments in my history, as I wanted to give it enough time to do something – if it did anything at all.

Testing Hiccups

Over the course of the experiment, I ran into a few problems with testing. You can read about the details below, but to summarize:

  • I needed to re-test my baseline, I did so by extending my baseline 1 day and re-testing the following morning.
  • The baseline microbiome results were lost
  • The post-intervention PEG400 data was lost
  • The two final tests were confounded by a cold and by a sunburn
Testing Issues In-Depth
The first was during my first baseline lab, on the 28th of May, the cholesterol reading I took after my blood draw (via a home monitor) indicated my triglycerides were unusually high. To ensure I collected accurate baseline data, I extended my baseline by one day, and re-tested everything the next morning. I suspect the confounder was the PEG400 testing, as the original labs did come back odd.

The data from the microbiome test I had done at the end of the baseline was lost as well – the company I was testing through (ubiome) discontinued support of the smartgut testing a day or so before I sent in my sample and cancelled my order as a consequence. I did however get a test at the end of the experiment via their explorer kit.

I was able to get a PEG400 at the end of the baseline, and got those results back fine. However the other kit I had for testing at the end of the intervention had apparently leaked in transit, and I wasn’t able to get a replacement fast enough due to an issue with the label on the replacement.

The final two blood tests were confounded due to 1) getting a cold and 2) getting a sunburn by falling asleep outside on accident. This definitely impacted the results, so unfortunately the blood data likely isn’t representative. I was working under some time constraints, and didn’t have time to extend the baseline further, but I did get another test when on unrestricted ketoAF a month or so later, so will provide that at the end, as it wasn’t part of the original experiment.

Prior Diet and Baseline

Prior to the experiment I had been following a predominantly carnivorous diet (barring experiments, etc) as of October 2017 (a little under a year and a half). I had lost an additional 25 pounds from switching to carnivore from omnivorous keto, bringing me down to 140 lbs. For around a year I had been at 143 lbs without additional weight loss. To note, this still left me “overweight” (and overfat, according to a DEXA). Throughout ad libitum carnivore I averaged around 30% protein, 70% fat and negligible carb from seafood and dairy.

Final baseline diet composition.

The baseline diet was originally intended to be 10 days, starting at May 17th, but was ultimately 7 days, starting at May 20th to May 26th. The first three days of the original baseline had unusually high glucose readings, and I also realized I was eating too fatty for my intended 1:1 target, so these three days were excluded.

Final baseline diet composition.

During the 7 day baseline I tracked morning glucose, ketones, and weight. I ate ad libitum, and logged all items consumed via pictures.

During this period I consumed:

  • Trimmed ribeye
  • Coffee
  • Water
  • Vitamin supplements (vitamin D, and methylated B vitamins)
  • Electrolytes as needed

After the baseline was completed I tested intestinal permeability with a PEG400 from ICMNI, as well as a slew of bloodwork which was repeated at the end of the intervention.

My baseline PEG400 returned the following result, with the comment “[It is] normal, even lower than the reference range which is characteristic of those not eating plant foods.”

I ended up having to re-test the bloodwork the next day, as discussed, thus on the 29th I did another set of blood tests which we will consider the official baseline bloodwork, here.

Intervention Design

The intervention diet was set up to be ad libitum, eating when hungry until full and avoiding fasting beyond 24 hours if possible (to ensure any weight loss was not due to the fasting/ensuring I didn’t confound any lab results). I wanted to make sure I gave it sufficient time to show positives or negatives so ultimately decided on 26 days. The goal was not protein restriction, but rather fat prioritization so meals generally followed this pattern:

  1. Eat raw beef trimming until no more was desired (satiety)
  2. Eat raw beef liver (75g) next – this was included as I had stopped B vitamin supplementation, raw liver was best tolerated compared to other preparation methods.
  3. Eat trimmed ribeye (main protein source) until satiated.

The “goal” would be 2:1 fat:protein by macronutrient gram, but if I got full before I reached this, it wouldn’t be forced, and if I ate above the ratio (more fat) this would also be fine. All food was weighed and logged via pictures. Supplements and coffee were discontinued during the intervention period. Weight was taken each day, along with glucose and ketones (BHB).

I had two check-in labs, mostly to verify my folate levels were remaining stable with the removal of supplementation and addition of liver. On June 24th, the end of the experiment I tested the following:

  • Microbiome test
  • Blood work
Blood Tests Done Over The Experiment

Late Game Change to Intervention Diet

Originally, the intervention diet was supposed to include 75g~ of raw beef liver per day. However, after a couple weeks, I began to feel averse to eating it. I continued eating it, as part of the experiment design, however this rapidly turned into nausea after consuming it at meals.

On 6/17 the reaction to eating the liver escalated into becoming physically ill after eating it. In order to make sure I could continue the experiment, I decided to discontinue liver consumption for the duration of the experiment.

I’m not sure why this happened, exactly, as the reaction was disimilar to food poisoning, especially as the reaction increased over time. Some I’ve spoken to have speculated the aversion may have been due to being “topped off” on a certain nutrient (or nutrients) found in liver, but I have no way of verifying this.



During the baseline (5/22-5/28) I remained weight stable, fluctuating between my normal weight of 145-147 lbs. After the KetoAF intervention, I remained weight stable for four days, after which my weight began to decline. My weight continued to decline at a steady rate, with the exception of a period where I had a cold (6/9-6/14) during which I was weight stable. The week after the cold cleared (6/14-6/18) I was also stable at a slightly lower weight, but it is unclear if this is related.

The decline in weight continued until the end of the experiment (6/24). The total weight lost from the lowest weight of the baseline (145 lbs) compared to the lowest weight of the intervention (138 lbs) was 7 pounds. At 5’2″, and considering this is the lowest weight I’ve achieved during my adult life, I would consider this weight loss significant.

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Macronutrient and Energy Intake

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During the baseline, I averaged 1855 calories per day. During the first two weeks of the intervention, calories dropped to about 1750 calories per day – resulting in about a 100 calorie decrease from baseline. Average fat grams increased from 122g per day to 164g per day, and protein decreased from a daily average of 148g to an average of 51g per day.

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On the last day of my cold (6/13) I did not eat as I was not feeling well. This resulted in week 3 having a low average calorie intake. Unfortunately, week 3 is also missing data for one day (6/18). I know I didn’t fast that day, but can’t find picture logs of what I ate. In order to not artificially depress the average, this day has been excluded from all calculations of averages.

Finally, the average calories for week 3.5 was slightly lower than weeks 1 and 2 at an average of 1683 calories per day – on average, 67 calories less per day.

Over all it appears as though eating a carnivorous diet with a high fat content did not result in an increase in energy intake, and indeed seemed to result in a general decrease (100-200 kcal/d). Despite being very energy dense, appetite appeared to be properly regulated. It’s also interesting to note that although week 3 was the lowest calorie week, this did not correlate to more weight loss – in fact, I did not lose weight during this time period.

Calorie Data By Week

Ketones and Glucose

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Over the course of the experiment, a significant difference in average ketone level was recorded. During the baseline, average ketone level was 1.5~ mmol/L and over the course of the intervention average ketone level was 2.8~ mmol/L.

Glucose levels were not significantly different during the duration of the experiment, with an average of 89.8 mg/dL during baseline and 90.0 mg/dL during the intervention.


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At baseline, my Total Cholesterol and LDL Cholesterol were 312 mg/dL and 251 mg/dL respectively. By the end of the experiment these had decreased by 88 mg/dL and 83 mg/dL respectively, to 224 mg/dL and 168 mg/dL.

HDL remained within my normal range throughout the experiment at 45 mg/dL, while my triglycerides decreased by 26 mg/dL from 82 mg/dL to 56 mg/dL.

It’s possible that these results were confounded by the cold and sunburn at points 6/13 and 6/24, however a follow-up lab on 8/2 showed Total Cholesterol of 231 and LDL-C of 155 mg/dL, as well as triglycerides of 45 mg/dL so I find it likely these are representative. HDL at follow-up was 67 mg/dL but it is unclear if this is a one-off or a new normal. Further testing on all of these points will be beneficial.

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Vitamin B12 and folate both increased during supplement cessation and liver inclusion and dropped somewhat post liver exclusion. A longer time trial without liver would be needed to see where they settled longer term.

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Throughout the experiment Vitamin C levels remained steady with a small decrease in Vitamin A and a decrease in Iodine. It’s unclear if the decrease in Vitamin A was impacted by cessation of liver consumption.

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Glucagon increased from baseline and insulin generally decreased (excluding one datapoint on 6/13 from when I was sick; not shown). They appeared to mirror each other over the course of the experiment.

Free T3, and IGF-1 both decreased over the experiment. Longer term tracking of Free T3 would be needed to gauge relevance versus fluctuation. Low T3 is not entirely surprising due to a very high fat, low carb diet as mentioned in this post. No hypothyroid symptoms were noted during the course of the experiment, and energy levels remained stable.

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Uric acid, interestingly, increased over the course of the experiment. Further testing would be required to gauge whether the increase in Uric Acid was temporary due to a deeper level of ketosis (as evidenced by higher ketones) as noted by Westman Et Al that this can cause a temporary increase in Uric Acid during keto adaption. The follow-up test from 8/02 showed uric acid was back to 6.2 (data not shown), so this is suspected in this case. Further testing over a longer time period is warranted.

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Finally, although possibly confounded by the circumstances of the last two data points, lipoprotein(a) levels generally decreased during the experiment, just as LDL-C did. This is consistent with Lp(a) following LDL levels over the course of various experiments, with its role as an acute phase reactant in mind given the cold and sunburn of the last two tests (possibly elevating it above what it might have been otherwise). Longer term tracking would be interesting to see if this is sustained over a longer time period.

Final Comments

Ultimately I greatly enjoyed ketoAF as a way of eating over the course of the experiment, minus the liver incident. Since the experiment, I’ve been using ketoAF as my baseline diet including at conferences (e.g. at Low Carb Houston I ordered moist brisket with a side of butter). I find it easy to do even when away from home, and my food enjoyment has increased.

I’ve found it to be a helpful tool post-High Carb Experiment (post on this one coming soon), to help come back from the weight gain and adverse side effects that lasted long after the experiment. I find I will likely continue it longterm as long as I continue to enjoy it. Longterm data will certainly be interesting, especially if it allows me to come down to a normal/lean weight/bodytype given enough time.

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Siobhan HugginsRafaelTuanChristieJohn Recent comment authors

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eric feitler
eric feitler

This is great! Can you clarify the raw beef and liver trimmings part. I love raw meat but dont eat it often due to sanitary concerns. Dont think I would enjoy raw fat. Did you actually eat all that raw as described? Thanks

Brian Lenzkes
Brian Lenzkes

Wow! This is truly remarkable. Glad I didn’t bet money on the outcomes! Strong work.


What was your diet heading into this test (i.e. what was responsible for the TC and LDL of 312 mg/dL and 251 mg/dL)?
And what do the PEG400 results mean? Is lower recovery % good or bad?


Why raw liver and raw beef?
And, maybe I missed the point, but what was the objective of the experiment?

Tom Andersen
Tom Andersen

Maybe I should upper my fat intake rather than CHO to normalize my LDL 🙂

Heather M Carr
Heather M Carr

Excellent work. Very interesting!


Liver has a lot of vitamin A. Too much can be toxic. Your body was probably telling you you’re getting too much vitamin A..

Bruce Moore
Bruce Moore

Hi, I’m also interested in what you meant by “trimmed ribeye”. Does this mean you trimmed the meat off to leave more fat or the other way around? I’m trying to get my fat content up to 2:1 protein but finding it difficult with regular ribeye and other steaks. Trying also to cook eggs in tallow but doesn’t taste that good. Also, just wondering if you tried cooking the liver would it have made it more palatable?
Thanks for your work on this.


Hi Siobhan, your experiment has been illuminating, especially about the liver. I commented earlier in the experiment that I have been eating liver almost daily since I realized it gives me some kind of energy boost and mental clarity. My intake was sometimes lower than yours, usually ranging between 40-80 grams, and always raw. I have also noticed if I go more than 3 days without the raw liver, the benefits go away and my mood is lower. I have been trying to figure out what nutrient(s) I must be deficient in, so if anyone in your community has a guess, would lover to hear. I eat lots of eggs, other organs (here in Spain we get nose to tail easily), and no supplementation other than D/K2 irregularly. I rarely eat plants, sometimes an avocado or olive oil. I eat rare or raw in the warm months and more cooked meat in the cold months. Been eating carnivore for nearly 3 years now but the liver just the last year.

When I saw that you were supplementing with methylated Bs, it made me wonder if you were getting too much of one or more B vitamins during your experiment. Were you taking them concurrently with the liver? What was your reason for including them? My apologies if you have explained this and I missed it. Thanks for all you do – it’s been a fascinating experiment to follow.


Hi, thank you for your great website, I also watched your video and it made me less worried about my recent Cholesterol test. I started keto in January 2019, here are my numbers before keto and while being on keto:





I would love to try your method before my next test but was wondering if the “no coffee” and “no MCT oil” would be only for those three days prior to the test or all the time? Thanks again

Weekend Knowledge Dump- November 15, 2019 | Active Response Training

[…] #KetoAF Experiment Results – Trialing High Fat Carnivore […]


So,if your glucagon went up and your insulin went down, this would imply your blood sugar went up. Did it?


Just heard your great interview on Low Carb MD podcast, and would like to take you up on your offer to leave comment here.

65+ male doing LCHF / KetoAF for 2 years, IF 16:8 for 1 year, high intensity resistance training to MMF for 5+ years. 
17% BF (per Bodpod), BMI = 21, waist to height = 0.48

Total Cholesterol (fasted) = 347,  LDL = 240,  HDL = 94,  TG = 66, (TG/HDL = 0.7)
Fasting Glucose = 108 mg/dL
Hemoglobin A1C/Total Hemoglobin =  5.5%
Fasting Insulin = 11.1 uIU/mL
HOMA IR = 3.0

Given my diet and life style I expected high LDL but not the high Insulin.

Would appreciate your comments


I am curious as to since I started carnivore my liver enzymes have increased alot. My ALT went from 16 -55 since starting carnivore. The test was 6 months into carnivore. My AST also rose from 23 -40. They did an ultrasound and hepatic bloodwork and everything was normal. I would love some input.


This is awesome! I was in Keto about 1 year and been on Carnivore for 5 months now. My A1C is 6.1, glucose is 123, Triglyceride is 109, HDL 59, LDL 377. I ate most ground beef 80/20. Could you give me your thought please?


Hi Siobhan,

I really enjoyed your experiment above. You really kept detailed track of all the variables. I’m curious for your theory of why Keto AF would be better than Keto plain.

I’ve found that when I do Keto Af for a while, I tend to get muscle cramps, sometimes in the legs and sometimes in my whole body. I’ve supplemented with salt, potassium and epsom salt baths. I’m curious if you have any other ideas.