All Of Your Burning Keto Questions Answered: Fasting On Keto, Keto For Fat Loss, Keto Nootropics & Supplements, & Much More!

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I've been experimenting with some semblance of a ketogenic diet for nearly a decade now – specifically for a host of goals, including muscle gain, ultra-endurance, longevity, cognitive performance, and beyond. I have used a low-carb, cyclic ketogenic, and strict ketogenic approach to power through Ironman triathlons, Spartan races, intense kettlebell training, and more. At 6'3″ and 185lbs, it has also been one of the nutritional keys that have allowed me to maintain 5-6% body fat year-round. 

Additionally, I've covered the ketogenic diet extensively on my blog in the following articles and podcasts:

I tell you all this to not only illustrate how much of a proponent I am of a carbohydrate mitigation approach – and often a full ketogenic approach – for optimal, all-around health and wellness but also to emphasize that there's far more to ketosis than simply chugging ketones, putting coconut oil or butter in your coffee, or eating 5% carbs/25% protein/70% fat year-round.

So, to help folks out there struggling with keto, last month I hosted an AMA (ask me anything) on Reddit where I took questions on keto, carnivore, carb-cycling, metabolic efficiency, nutrition biohacking, and more. The AMA seemed to produce some valuable content, but, because it's admittedly all a bit difficult to sort through, I decided for today's article to pick out the top 30 keto questions that I thought would be most helpful to you, then organized them according to categories such as “fasting,” “cognition,” “supplements,” “carb-cycling,” and more to make this mountain of information a bit easier to digest.

Enjoy, and leave your own questions, comments, and feedback below!

Keto Questions On Fat Loss

1. I'm six weeks into a strict ketogenic diet, and I have lost only 3 pounds. This seems very slow compared to what everyone else reports. Do you have any tips for expediting fat loss?

There are actually 16 reasons that, despite a calorie deficit, folks tend to not lose fat. I highlight many of these in detail in Boundless, but I think a few of the important ones that come immediately to mind are:

  • Low levels of physical activity despite “hitting the gym.” I recommend shooting for a minimum of 15K steps per day to address this.
  • Not enough temperature fluctuation. I recommend cold thermogenesis for 5 minutes in the morning in a fasted state, and again in the evening pre-dinner.
  • Metabolic downregulation due to excess carb restriction/calorie restriction, which can be alleviated with targeted weekly refeeds.
  • Inflammation (which can occur in response to high saturated fat intake in the absence of fiber/phytonutrients) impairing fat cell lysis.
  • Sleep deprivation, which is known to raise cortisol levels, reduce glucose tolerance, and increase sympathetic nervous system activity—all of which may hamper fat loss. Check out my comprehensive sleep article, “The Last Resource On Sleep You’ll Ever Need: Ben Greenfield’s Ultimate Guide To Napping, Jet Lag, Sleep Cycles, Insomnia, Sleep Food, Sleep Supplements, Exercise Before Bed & Much, Much More!” for more on optimizing sleep.
  • Micronutrient deficiencies: Specific micronutrient deficiencies are associated with weight gain and obesity. Among these micronutrients, the most significant are vitamin D, chromium, biotin, thiamin, and antioxidants. Deficiencies in these specific compounds can prevent fat loss via mechanisms that include altered insulin gene transcription, amplification of intracellular insulin-signaling, and changes to glucose and amino acid metabolism. Metabolism and resistance to weight loss are also negatively affected by deficiencies in magnesium, boron, vitamin A, vitamin K2, and choline

Keto Questions On Fasting

2. When fasting overnight, should I drink baking soda and ascorbic acid in the morning? Or will this ruin the fasting/autophagy?

Neither of those break a fast. Someone recently asked me for my morning routine, which includes this same type of drink in a fasted state. Here is it, in a nutshell:

  • Wake and complete gratitude journal while laying in bed. Do not take phone out of airplane mode.
  • After journaling, go to kitchen and drink 30 ounces of water from a glass mason jar. Into water, place two packets or vials of Quinton hypertonic minerals (use code GREENFIELD for a 10% discount) OR a teaspoon of good salt, along with 1 teaspoon baking soda and 2 hydrogen tablets. If you add Vitamin C, which I recommend, use twice as many g of vitamin C as baking soda (e.g. 10g vitamin C + 5g baking soda).
  • Drink, then proceed outdoors into sunshine in bare feet wearing as little as possible. Complete 10-15 minutes of stretching, foam rolling, and deep tissue work, specifically focusing on anything that feels tight or painful. During this time, feel free to listen to encouraging, spiritually enhancing music, or an audiobook or podcast, but continue to keep phone in airplane mode.
  • Upon finishing stretching and breathwork, use restroom, then, if time permits, proceed to 20-30 minute sunshine walk or sauna and ice (use code BENFORGE for $150 off the retail price for any Forge) therapy (otherwise can save hot and cold for later in day).

3. What are your recommendations for an optimal extended fast, and how long have you personally fasted before? Are there any added benefits for fasting longer than 72 hours?

Autophagy benefits seem to kick in at about 16 hours, sometimes earlier in exercising and fat-adapted individuals.

  • Within 24 hours, your cells are increasingly recycling old components and breaking down misfolded proteins linked to Alzheimer’s and other diseases.
  • By 48 hours without calories or with very few calories, carbs, or protein, your growth hormone level is up to five times as high as when you started your fast.
  • By 54 hours, your insulin has dropped to its lowest level point since you started fasting and your body is becoming increasingly insulin-sensitive.
  • By 72 hours, your body is breaking down old immune cells and generating new ones.

I think there are certainly some spiritual and psychological benefits that kick in even beyond the 72-hour window, but I personally do as follows:

  • 24-hour dinner to dinner fast 2x/month.
  • Daily 12-16 hour fast with an exercise session at some point during that window.
  • Quarterly fasting-mimicking diet (at Prolon, you can use code BEN for a free gift) at 40% my normal calorie intake for 5 consecutive days.

I have yet to fast beyond the 3-day mark, personally. It's actually on my radar for this upcoming year.

Keto Questions On Cognition

4. What's the ideal time to eat for cognitive and physical performance? For example, one meal a day (OMAD) in the morning or night. Eating after exercise or waiting?

OMAD studies seem to indicate overall metabolic superiority for morning feedings, but they haven't yet investigated if effects are paralleled with a shift to an evening feeding preceded by a workout, which I suspect would elicit similar mechanisms. Based on the insulin sensitivity and upregulation of glucose transporters induced by an exercise session, if I were to go OMAD I would choose dinner (also convenient because that is the most social meal of the day anyways) but precede it with a weight training or HIIT workout to ensure glucose deposition into the liver and muscle tissue, insulin sensitivity, and also to block any potential for sleep disruption from nighttime hypoglycemia—provided any carbs eaten with dinner aren't very high glycemic index.

5. What’s the youngest you would recommend someone start with keto or nootropics to help with school?

I'd be cautious with any synthetic smart drugs of course and have to be careful with giving advice for putting children on an overly restricted diet.

When it comes to natural nootropics though…

Omega-3 fatty acids such as those found in fish oil have been shown to help children with reading and writing disorders, dyspraxia (developmental difficulties that result in troubles with coordination), and attention deficit hyperactivity disorder (ADHD) symptoms. They may also help boost mental performance in children aged eight to twelve with ADHD and produce symptomatic improvements in hyperactivity, behavior, and the ability to think clearly. (This has been shown in research involving children seven to twelve years old who were given a supplement containing fish oil and evening primrose oil.)

Zinc is also interesting for this. It is used in the metabolism of melatonin, which is important for the regulation of sleep and dopamine, which could help learning, attention, and emotional response. Studies have also found zinc supplements to decrease impulsivity and hyperactivity in children. (For children between the ages 9 and 13, the RDA of zinc is 13 mg.)

Another two are L-Theanine, which appears to be safe for children and may reduce hyperactivity and be useful for kids who have ADD and ADHD tendencies and phosphatidylserine, which is used for forming the lipid bilayer of neurons, which could also be helpful for the growing brain of children.

My boys don't take nootropics, but I do ensure they get plenty of choline, and their diet is rich in coldwater small fish (sardines, mackerel, herring, anchovies, etc.), walnuts, egg yolks, and also liver (organ complexes like Ancestral Supplements (use code BEN10 to save 10%) and Paleo Valley (use code BENGREENFIELD10 to save 10%) also do the trick if you can't get your kids to eat organ meats) a couple of times a week. They have the same organ meat sausages I talk about here with scrambled eggs a few times a week for breakfast.

Keto Questions On Supplements

6. What supplements & dosage do you recommend for people doing keto and intermittent fasting?

My top picks, although dosages are going to vary widely based on body size and activity levels, would be as follows:

7. What is the easiest way to make sure I get enough electrolytes?

Celtic salt is readily available just about anywhere and is very high in minerals and also low in metals and microplastics. It has a pretty good flavor profile too. But nothing beats, in my opinion, Quinton Hypertonic Elixir (use code GREENFIELD for a 10% discount). Listen to my podcast with Robert Slovak about this.

8. Your rocket fuel endurance recipe of Ketones, Thorne Catalyte, Kion EAA, and Gaspari Glycofuse works well until my stomach turns sour after 10hrs of this fuel. Are the ketones to blame or just too much acid in the form of supplements?

It's pretty rare to not have any gut issues at all once you exceed about eight hours of endurance exercise, especially running. Some people who don’t do well with ketone esters do better on a 50-50 blend of Ketone esters/Ketone salts. Loading with colostrum for about two weeks prior to your competition helps quite a bit with gut permeability issues too. Peppermint essential oil applied to stomach topically can be handy also, I've found.

Keto Questions On Carb Cycling

9. What is carb cycling and what does it look like for you?

Pretty simple really—carb cycling involves targeted re-feed of carbohydrates in the context, typically, of a low carbohydrate or ketogenic diet, to ensure that glycogen levels stay adequately elevated for purposes of things like performance or muscle gain or that metabolic rate is not down-regulated due to long-term carbohydrate deprivation. Listen to this podcast to learn more about carb cycling.

Carb cycling for me involves…

  • Eating zero net carbs the entire day until post-workout feeding, which is a dinner that typically occurs with 1-3 hours after a 30-60 min workout that falls sometime between 4:30 and 6:30 pm.
  • I then re-feed with starches up to 150-200g from sources such as millet, sweet potato, yam, white rice, red wine, dark chocolate, etc.
  • I then intermittent fast for 12-16 hours, then rinse, wash, and repeat.

That has been my approach for the past 3 years, after following a more strict ketotic approach in the absence of such re-feeds and finding decreased tolerance to high-intensity workouts and a dysregulation of sleep cycles, thyroid, and testosterone primarily. The daily carb re-feeds seem to fix that, enhance sleep, and still allow me to be back into ketosis by the next morning.

10. When using a continuous blood glucose monitor, what range do you try to stay at when carb cycling?

Average fasting values below 90, and return to normal values within 45 to 60 minutes after eating is my sweet spot. I typically don’t go much higher than 140 postprandially. If I do, or if glucose remains elevated for longer than about an hour, that’s the type of meal I avoid in the future.

11. Why would you increase carbs before a race or competition?

Most races or competitions involve a hefty amount of glycolysis. Even a long-distance, endurance event like a marathon or an Ironman triathlon, for the more serious participants, involves multiple surges to a very high intensity that require some appreciable carbohydrate availability—more than you’d expect actually.

12. For increasing athletic performance on the carnivore diet, would you say that consuming carbs (mainly raw honey and maple syrup) immediately prior to or during my workouts would be the very best way to utilize them effectively and minimize glycemic variability?

This study indicates that (at least for endurance), the glycemic index is not super important if it's pre-workout. During a workout, high glycemic index formulations, such as a dextrose-based fuel, or a combo of maltodextrin/fructose is superior to low glycemic index carbs, and the same for the immediate post-workout window for rapid glycogen replenishment (if you're going to be working out again within 8 hours, particularly). And yes, no matter high or low glycemic index carbs, if you consume them pre-workout (or during/post-workout) you'll be inducing a temporary state of insulin sensitivity that would make them less problematic from a glycemic variability standpoint. I'm a fan of using minimal carbs for workout fueling, and instead ketones/essential amino acids/electrolytes. I discuss that approach in detail here.

13. Do you think one can have more carbs than required to maintain ketosis every day and still be healthy/lower blood sugar levels? How important is eating fish/omegas on the regular? Any opinions on mussels as a substitute for fish?

Absolutely. It really comes down to activity levels, and arguably, the metabolic and microbiome response to carbohydrate intake. I am convinced that omega-3 fatty acids are crucial for cell membrane protection, especially in the context of any appreciable amount of polyunsaturated fatty acid (PUFA) intake or even saturated fat (which can be inflammatory in the absence of much fiber/polyphenols). As far as mussels go…huge fan. Really good DHA and B-12 in those particularly.

Keto Questions On General Nutrition

14. Regarding omega 6 seed oils being toxic—is this the most important thing, or not really a big deal?

I'm not against polyunsaturated fatty acid intake within reason, particularly the essential linoleic acid. Some amounts of arachidonic acid are also necessary for inflammation modulation. But, chronic excessive intake of rancid or oxidized oils such as canola oil particularly, and a high intake of omega-6 eicosanoids overall is correlated with arthritis, inflammation, and cancer. I would shoot for at least a 1:1 ratio with omega-3s and choose healthy sources of omega 6 oil such as grapeseed oil, evening primrose oil, borage oil, black currant seed oilflaxseed oil, or linseed oil.

15. What's your position on cheese? Is there any food that should be avoided in a cheese combination due to any reaction while digesting?

I try to choose A2 dairy sources of cheese, which is a form of protein that is less inflammatory. A2-beta casein is less inflammatory and here is a good resource on how to source those types of cheeses, which are often the hard, artisanal European variety.

16. Is there something about keto that makes dairy easy to digest? I have lactose intolerance issues when I eat “regular,” but no issues with increased dairy when I eat keto.

Sometimes the absence of grains, vegetable oils, etc. due to elimination of a wide variety of problematic foods while on a keto diet can induce a gut-healing effect, which is important since the villi in your intestine product lactase that helps to digest lactose, and, if damaged, that lactase production is significantly limited.

17. If fueling a marathon with fat, how should I prepare nutritionally both before and during the race? Do I need to take on calories during the race?

I recommend the exact approach I describe here for fueling endurance with a keto-friendly approach of exogenous ketones and/or MCT oil, electrolytes, essential amino acids, and very low amounts (25g/hr) of an easy to digest starch such as dextrose fuel. You can—with that approach and adequate time (6+ months, preferably) of fat-burning adaption leading into the race and a pre-race meal that is more fat-based (fatty coffee)—sustain pretty impressive levels of energy throughout without bonking. Though you'll likely still find that towards the end of the race you may need to shift towards gels, Coke, etc. for that final glycolytic kick.

18. How sure are you about the number of calories you are eating? Do you just guesstimate your serving sizes and portions, or do you know down to the gram each serving of each food you eat?

I rarely measure, but occasionally feed my intake into Cronometer to “check in” out of sheer curiosity. I find constant measuring and tracking seem to suck the enjoyment out eating, and I instead intuitively pay attention to satiety, sleep, and HRV and that seems to work very well. Every time I feed my data into Cronometer it tends to fall between 15-30% based on my intuitive approach, and the fact that I simply don't eat carbs at all until a nightly post-workout refeed of around 150-200g max.

19. What do you think is a good carb source, aside from honey, for the carnivore diet either on a day-to-day basis or more cyclic.

Underground storage organs for sure: carrots, parsnips, sweet potato, yam, purple potato, etc. Millet is also a very digestible grain and one of the few fully “gluten-free” grains out there—quite nutrient-dense too.

20. What kind of meal do you suggest prior to weight training?

I prefer to work out mostly fasted, but often take 10-20g of essential amino acids and sometimes also combine those with ketone esters and electrolytes for a “fasted-esque” workout that still allows for high workload/anabolism.

21. How much protein can you absorb at once, and is eating too much pointless?

Research varies, but the sweet spot tends to be 30-40g. Once above 50g, some digestive distress can set in for many people. Some pretty interesting effects on protein overfeeding are listed here. Notable that “protein overfeeding or the consumption of a high protein diet may not result in a gain in body weight or fat mass despite consuming calories that exceed one’s normal or habitual intake.”

My Thoughts On The Carnivore Diet

22. What do you think about the carnivore diet?

The carnivore diet falls into the same general category as the ketogenic diet since it is a very low carbohydrate protocol that can potentially set you up for many of the same deficits or issues people experience when going keto. The difference between a carnivore diet and a ketogenic diet is that, although a carnivore diet can (and based on what you read below should) be ketogenic, it is higher in protein and lower, or absent, in many of the common staples of a ketogenic diet, such as butter, coconut oil, seeds, nuts, plant-based oils, etc.

On a strict carnivore diet, one eats only meat (preferably nose-to-tail), fish (sardines, mackerel, herring, anchovies, etc.), water, and little else, although some variations allow for animal-derived foods such as butter, dairy, and eggs. So breakfast might be a cut of wild salmon, lunch a large ribeye, and dinner a serving of a rack of lamb.

However, if you eat exclusively meat, you can disrupt your microbiome, particularly via a shortage of the short-chain fatty acids (SCFAs) called butyrate, which your gut bacteria use as fuel to maintain the integrity of the intestinal wall. Research has indeed shown that an all-meat diet can lead to SCFA deficits. In addition, an interesting study found that cheetahs are able to ferment collagen from bones and chicken cartilage into SCFAs, and the same may be possible for humans on a carnivore diet who make sure to include bone broth, bone marrow, and other cartilaginous sources, such as many of the newer bone broth powders with added cartilage, in their diet. In addition, many of the benefits of fiber are attributable to its fermentation by bacteria that produce SCFAs in the colon, especially one called butyrate. However, it turns out that SCFA has metabolic properties that are very similar to those of beta-hydroxybutyrate ketones (BOHB).

In the presence of low carbohydrate intake, the internal production of BOHB by the liver may reduce or eliminate the need for butyrate produced from a higher fiber diet, which can be especially good news for people who experience gas, bloating, or other gastrointestinal distress from a high consumption of seeds, nuts, grains, or vegetables (particularly roughage and raw veggies). Therefore, a well-formulated ketogenic or low-carbohydrate carnivore diet may provide many of the benefits of fiber, without a high carbohydrate intake and the associated unpleasant side effects that some people experience from high fiber intake.

In other words, if you are in nutritional ketosis from a ketotic diet or a low-carb carnivore diet, it may not be necessary to consume a high fiber diet to achieve the health effects attributed to fiber.

Since red meat is also quite high in the amino acids cysteine, tryptophan, and methionine—which can be pro-cancer and pro-aging in excess—anyone on the carnivore diet should also prioritize getting adequate glycine, proline, and hydroxyproline, all of which can balance out the other amino acids and also further support a strong gut lining. This is another good reason to include bone broth, collagen, glycine, essential amino acids, and organ meats as they are high in these particular amino acids.

Finally, due to the low intake of plant matter, the carnivore tends to be low in vitamins C and E, and if dairy is not included, also vitamin K2 and calcium. If organ meats aren’t consumed on a carnivore diet, it also becomes low in Vitamin A, folate, manganese, and magnesium, which are crucial compounds for normal, healthy metabolic function.

In reality, it is very rare to find a long-lived, healthy population that subsists entirely on meat, especially muscle meat. For example, several Asian, Latin American, and African tribal cultures actually consume the intestines of ruminant animals like goats, sheep, deer, and cows—all of which contain high amounts of the vegetables and fiber those animals consumed, a literal stomach salad! These include dishes such as the Spanish zarajos, the Filipino dinuguan, the Korean gop chang, and the Latin American chinchulines.

Many argue of the existence of carnivorous ancestral populations. While it’s true that many of our ancestors thrived on large quantities of animal products, every single one of the commonly cited carnivorous groups also took significant advantage of plant foods. For example:

  • The nomads of Mongolia ate plenty of meat and dairy products, but consumed wild onions and garlic, tubers and roots, seeds, and berries.
  • Gaucho Brazilians consumed mostly beef, but also supplemented their diet with yerba mate, a tea rich in vitamins, minerals, and phytonutrients.
  • The Maasai, Rendille, and Samburu tribes of East Africa primarily consumed meat, milk, and blood, but also occasionally consumed herbs and tree barks. Women and older men in these communities consumed ample amounts of fruit, tubers, and honey.
  • The Russian Arctic Chukotka thrived on fish, caribou, and marine animals but always paired these animal foods with local roots, leafy greens, berries, or seaweed.
  • The Sioux of South Dakota ate large amounts of buffalo, but also consumed wild fruit, nuts, and seeds that they came across as they hunted the buffalo herds.
  • The Canadian Inuit subsisted primarily on walrus, whale meat, seal, and fish, but also foraged wild berries, lichens, and sea vegetables and even fermented many of these plant foods as a preservation method.

Granted, one could argue that many of these populations turned to these plants as survival food, and that they (and modern humans) could thrive on eating animals nose-to-tail, along with fish, in the absence of such plant matter. However, this may not be sustainable for the planet, accessible to many people, or enjoyable (since it would require getting rid of a rich, tasty, and satisfying tradition of consuming plant compounds such as coffee, red wine, sourdough bread, sweet potato fries, beet salad with goat cheese, or any of your other favorite foods that are plant-derived).

Finally, researcher Richard Wrangham hypothesizes and presents good evidence that the relatively large brain and small gut of the human didn’t happen from eating more meat (which the carnivore diet enthusiasts propose) but from eating more starchy underground storage organs, such as tubers and root vegetables.

In a nutshell, all things considered, if I were to eat a carnivore diet (and this has been my approach in the past when implementing such a diet), I would not only eat nose-to-tail, organ meats, bone marrow, and bone broth, but I would also add:

Keto Concerns

23. I was wondering if you could point to any research on 1) Keto and heart disease, and 2) Starting the keto diet in old age.

1) Low Carb Cardiologist has a fantastic article about this—and particularly highlights heart-healthy benefits such as insulin regulation, cell membrane integrity, high HDL cholesterol, autophagy, and ketone production. But one 2010 study of low-carb dieters found that those who focused on vegetable-based sources of fat and protein had a 23 percent lower risk of heart disease than those who relied more heavily on meat-based sources, so including plant matter in a keto approach appears to be beneficial. 2) I haven't seen much research on keto/seniors, but I'd prioritize protein and protein-digesting enzymes like protease and not let protein fall under 30%. For older adults, probably the biggest risk of keto (or fasting) is that you may deprive your body of the protein it needs to build and maintain muscle mass or stave off sarcopenia.

24. Is it a myth that severe low carb damages your thyroid, in particular your T3 levels?

It can, particularly if you go for longer than four weeks without any re-feeds (unless you’re using ketosis for managing a medical condition). This is why I recommend daily re-feeds for very active athletes or exercise enthusiasts and weekly re-feeds for most people.

25. For females, would you recommend increasing carbs in the luteal phase and avoiding fasting during those weeks?

No. Beta-oxidation and fat burning tend to INCREASE during the luteal phase, so that would be exactly when you could handle lower carb intake and more fasting! Brad Dieter has good thoughts on that here. Alisa Viti's book, In The FLO, is a very good resource too.

26. How do we overcome heartburn on carnivore if apple cider vinegar doesn’t work?

I’d look into your gut bacteria (use code BEN20 to save $20) because gut dysbiosis can be a big contributor to heartburn. I’d also look at pancreatic enzyme production (GI Effects® Comprehensive Profile – Stool (Three Day Collection)-Genova Kit), and consider using more proteolytic enzymes. You may also want to consider a supplement that includes ox bile extract and even hydrochloric acid.

27. What would you recommend for sleep in the context of a ketogenic diet?

It's pretty common that carbohydrate deprivation long term can affect sleep quality due to suppressed serotonin, and one of the best ways around that is to include carbs with dinner. It doesn't have to be a full-on 100-200g carb refeed as I do, but even half a sweet potato with a dab of honey or a bit of red wine with extra dark chocolate can do the trick. You may also want to try glycine. Two to four grams of glycine can be really great for enhancing sleep quality in the absence of an appreciable amount of carbs.

28. I was curious as to why when I start going keto my sympathetic nervous system goes through the roof?

My hack for that is long breath exhales and occasional use of theanine. It's common for people to experience that with hefty use of exogenous ketones, btw, as they are quite stimulating (like common smart drugs or nootropics), but not so common with nutritional ketosis.

29. If fat in your stool bad?

Fat in the stool on a keto diet is common. Fat digesting enzyme compounds like Thorne Biogest or Kapex can help with that quite a bit, as can bitters and digestifs such as cocktail bitters (use code GREENFIELD10 to save 10%), unsweetened black licorice, lemon juice, etc..

30. I have been doing keto for the last four years as a therapeutic diet for chronic fatigue syndrome, but my cholesterol in the past year has gone up (235 LDL). Would you recommend I stop keto?

I'm not a physician so this is not to be considered as medical advice, but I personally don't consider high cholesterol to be problematic in and of itself unless the following risk factors are present:

  • High inflammation (e.g. measure your CRP, homocysteine, fibrinogen, and Lp pla2 to make sure those are within range).
  • High blood glucose (hbA1c and glucose are good markers to track, and also insulin).
  • High Trig:HDL ratio (under 4 is good, but I shoot for under 1).

So keep inflammation at bay (particularly by avoiding vegetable oils), blood glucose under 90 as an average, and triglycerides low with high HDL (particularly by keeping sugars and processed starches low and fiber/omega-3 fatty acids moderately high) and the cholesterol is likely to be more protective than harmful, IMO.


Keeping your body in a state of ketosis for extended periods of time can result in everything from decreased body fat and increased muscle mass to enhanced cognition—with even more profound impacts on certain diseases like cancer, morbid obesity, and beyond.

With that said, keto is not for everyone, and it's important to do your research and speak with a qualified professional before starting a ketogenic diet. I get into a ton of detail in Boundless about who should and who should not eat a ketogenic diet, and much of it is based on everything from genetics to liver/gallbladder function to level of physical activity and much more.

If you're thinking about starting a ketogenic diet, I highly recommend checking out some of the resources mentioned above first, doing your homework, and speaking with your doctor if you have any underlying medical issues.

As someone who's studied the science, seen first-hand what works and what doesn't, and most importantly, has gone through just about every variation of a ketogenic diet there is, you can work with me by checking out my personal coaching page here. I've also trained an entire army of Kion Coaches, which you can browse and connect with here.

So that's it! I hope to host more AMAs in the future on even more topics, so be sure to follow me on Reddit so you don't miss out on them. Let me know in the comments section below what topics you'd like to see me cover in the future, and as always, leave any keto questions, comments, or thoughts you have below.

Ask Ben a Podcast Question

15 thoughts on “All Of Your Burning Keto Questions Answered: Fasting On Keto, Keto For Fat Loss, Keto Nootropics & Supplements, & Much More!

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  3. Having been on the Keto diet for13 months, I suffer severe muscle cramps beginning about 20 minutes after eating any kind of bread or sugar.. I take from a quarter Tsp to a half teaspoon of salt, calcium and magnesium supplements, Sentrum Silver, every day. My potassium levels are already high, according to my blood work. When I told my doctor, she said it’s happening with high carb intake while on a strict KETO diet. It’s obvious that when I “reward” or have a “replenish day” of indulging in carbs, it come with a high consequence, That is hours of severe foot, leg, hand and arm cramps. Why after searching the web, have I not found a single report of these symptoms? It seems to me that once I go KETO, I can never go back. I’d like to have your opinion on my seemingly one in a million side effect of the KETO diet, Please.

  4. The blog is very informative and outstanding. I would love to read your blog. Give me lots of useful information. I will often visit your blog.

  5. John Crosby says:

    Ben, so grateful for all your work and resources. Could you clarify the vitamin C and baking soda ratio. I’m guessing baking soda is by weight–1 tsp = about 5 g–but is the C by weight or by dose? For example, a teaspoon of vitamin C is about 5 g by weight but could be a 2-4 g serving size of vitamin C depending on brand. Related, do you use straight ascorbic acid or a buffered source? Thanks so much.

    1. Joe says:

      I cane here for this too

      1. Joe says:

        Came* 🤦🏼‍♂️

  6. Desmond says:

    Thanks for the article. It really made y day. Here is a program that helped me maintain my fitness. I think it will help others too:

  7. Ashton K Long says:

    You mention “high activity-level athletes” should consider a daily refeed instead of just a weekly refeed. Would you define someone utilizing your “Perfect Two Weeks of Training” program in the book as high activity?

    If going the daily refeed route with this workout routine, and considering a weight of 150lbs, what would you say the sweet spot would be for carb intake on the back end of each day to mitigate all the potential issues of the keto diet?

  8. Jerry says:

    Ben Greenfield you are the man!

  9. Victória says:

    Hello Ben! Thanks for the article, very helpful

    I’m somewhat confused though in regards to question 25, which you said the luteal phase is the ideal period to fast and lower women carb intake and you specifically suggested Alisa’s book. But in her book, she suggests the opposite, claiming that in luteal our metabolism is more efficient, which we could get away with increasing our caloric intake and to prevent pms and hormonal disturbances pre menstruation, we shouldn’t stress our bodies with low carb, fast approches
    Do you have any thoughts on that, can you expand a little bit more on this subject?

    Thank you so much for the reply!

  10. Varun Sharma says:

    Is Keto diet causes low BP?

  11. Judd B says:

    Hey Ben,
    Given the substantial benefits to “medium term” (72h or less) fasting, out of curiosity why have you surprisingly not incorporated this practice into your routine?



  12. Kathleen says:

    In reference to #26, you say “ I’d look into your gut bacteria because gut dysbiosis can be a big contributor to heartburn. I’d also look at pancreatic enzyme production and consider using more prototypic enzymes“

    How would you look into gut bacteria? Pancreatic enzyme production? And what is prototypic enzyme and how to use more? Also do you recommend ACV for heartburn? I’ve never had any gut issues ever (60 years old now) and suddenly for 2-3 mo I have severe heartburn which is little better w betaine. I can’t even exercise bc heartburn gets increased.

    1. You could take Onegevtiy's Gutbio test:, which will give you personalized recommendations based on a stool sample you provide from home. For pancreatic enzyme production, the GI Effects® Comprehensive Profile – Stool (Three Day Collection)-Genova Kit:… Here are the proteolytic enzymes I recommend: And this is a pretty good article on some foods that could help mitigate acid reflux symptoms (ACV included):…

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