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Wondering what fits into a keto diet — and what doesn’t? “It’s so important to know what foods you’ll be eating before you start, and how to incorporate more fats into your diet,” says Kristen Mancinelli, RD, author of The Ketogenic Diet: A Scientifically Proven Approach to Fast, Healthy Weight Loss, who is based in New York City. We asked her for some guidelines.

The Inuit are often cited as an example of a culture that has lived for hundreds of years on a low-carbohydrate diet.[42] However, in multiple studies the traditional Inuit diet has not been shown to be a ketogenic diet.[43][44][45][46] Not only have multiple researchers been unable to detect any evidence of ketosis resulting from the traditional Inuit diet, but the ratios of fatty-acid to glucose were observed at well below the generally accepted level of ketogenesis.[44][47][45][46] Furthermore, studies investigating the fat yields from fully dressed wild ungulates, and the dietary habits of the cultures who rely on them, suggest that they are too lean to support a ketogenic diet.[48][49] With limited access to fat and carbohydrates, cultures such as the Nunamiut Eskimos—who relied heavily on caribou for subsistence—annually traded for fat and seaweed with coastal-dwelling Taremiut.[48]


1. If a set number ketones in the blood is an indicator that my body has transitioned to ketosis and not necessarily the cause (the cause being limited access to glycogen because of limited carb intake) then how does using exogenous ketones put me in ketosis as opposed to mimic being in ketosis (because when measuring blood ketones suddenly there are more because I put them there, I didn’t create them)?
The ketogenic diet doesn’t put a cap on saturated fat or even trans fats. The latter are fats you should always avoid. Read ingredient labels and avoid any food with partially hydrogenated oils, aka trans fats. These fats heighten your LDL (“bad”) cholesterol levels and lower your HDL (“good”) cholesterol levels. They also raise your risk of heart disease and stroke, according to the American Heart Association.

Ben, great article! I recently did my own ketosis experiment and didn’t catch the 100-200g advise until later than I should have, I’m guessing. Great results for 1-2 months but after 3 months I quit sleeping through the night and would wake after about 4 hours of rest each night. My guess is that the extra carbs at night coupled with iodine supplements should allow me to “have my cake and eat it too?” Any other suggestions on the sleep issue? I’ve gone back to High Fat/Low Carb, have improved sleep but I do miss nutritional ketosis and want to try again once my sleep is stable. Thank YOU!!!


BHB is the primary ketone your body can most efficiently use as fuel during exercise and at rest (especially when you’re keto-adapted), it is the most stable of the ketones, and it is actually found in nature in many foods including eggs and milk. A “BHB salt” is simply a compound that consists of sodium (Na+), potassium (K+), and the ketone body beta-hydroxybutyrate.

A small Feb. 20, 2017, study looked at the impact of a six-week ketogenic diet on physical fitness and body composition in 42 healthy adults. The study, published in the journal Nutrition & Metabolism, found a mildly negative impact on physical performance in terms of endurance capacity, peak power and faster exhaustion. Overall, researchers concluded, “Our findings lead us to assume that a [ketogenic diet] does not impact physical fitness in a clinically relevant manner that would impair activities of daily living and aerobic training.” The “significant” weight loss of about 4.4 pounds, on average, did not affect muscle mass or function.

^ Lockyer, Christina (1991). "Body composition of the sperm whale, Physeter cation, with special reference to the possible functions of fat depots" (PDF). Journal of the Marine Research Institute. 12 (2). ISSN 0484-9019. Retrieved 2014-04-25. The significant levels of carbohydrate, probably mostly in the form of glycogen, in both blubber and muscle, may represent an instant form of energy for diving via anaerobic glycolysis.
Our bodies are incredibly adaptive to what you put into it – when you overload it with fats and take away carbohydrates, it will begin to burn ketones as the primary energy source. Optimal ketone levels offer many health, weight loss, physical and mental performance benefits.1There are scientifically-backed studies that show the advantage of a low-carb, ketogenic diet over a low-fat diet. One meta-analysis of low-carbohydrate diets showed a large advantage in weight loss. The New England Journal of Medicine study resulted in almost double the weight loss in a long-term study on ketone inducing diets.
The remaining calories in the keto diet come from protein — about 1 gram (g) per kilogram of body weight, so a 140-pound woman would need about 64 g of protein total. As for carbs: “Every body is different, but most people maintain ketosis with between 20 and 50 g of net carbs per day,” says Mattinson. Total carbohydrates minus fiber equals net carbs, she explains.
A study in the Journal of Applied Physiology showed that people who do twice-a-day workouts, but defy standard nutrition recommendations by not eating for two hours after the first session (thus depleting carbohydrate stores with the first session) experienced a better ability to burn fat (with no loss in performance) compared with a group that trained only once a day and ate carbohydrates afterward.
Similar to the BHB salts and MCT’s from the KETO//OS I discuss above, powdered forms of ketones are excellent if you don’t want to completely eliminate carbohydrates or protein (which can be gluconeogenic when eaten in excess) or eat copious amounts of fats, but want to simultaneously maintain high levels of blood ketones. It may also be used to ease the transition into a ketogenic state, because it can help alleviate the fatigue and lethargy some  people experience while making the transition from a glucose metabolism (carb burning mode) to ketone metabolism (fat burning mode).
After 2 years in ketosis suddenly I find my blood glucose has risen to high levels even while in ketosis. I thought it was the dawn phenomenon, stress hormones like cortisol but now I am beginning to think I am eating too many exongenous keytones like too much MCT oil? I am not taking exogenous keytone supplements but wondering if too much oil/ fat in the diet generates exogenous keytones which inhibits the livers production of endogenous keytones. I have read if the liver is producing endogenous keytones it is not at the same time producing glucose through gluconeogenisis?
Weight loss is my favorite side effect of keto. Coming in a close 2nd, 3rd, and 4th, and 5th is higher energy levels, no bingeing, clear skin, and lowered blood glucose! I don’t mind telling people that I’m Keto...or shutting down a conversation where they try and spew their online doctor degree about how I’m killing myself. This WOE work is for me, my bloodwork is the best it has ever been, and I feel great. Keto on, friends.
This is why Gaspari Nutrition chose highly branched cluster dextrin for what we consider to be the gold standard of recovery and performance drinks. This high molecular weight carbohydrate has a special helical structure, which gives it unique properties unlike many of the corn starches or polysaccharides out there. I'll be real with you and say this stuff isn’t cheap, but you certainly pay for what you get, and highly branched cluster dextrin is unlike any carb source I've found – especially if you want to control blood sugar levels and gut issues.
For example, in trained people and athletes who eat a low-carbohydrate, high-fat diet (not to be confused with a low-carbohydrate, high-protein diet), a large amount of fat burning can take place at intensities well above 80 percent maximum oxygen utilization (VO2 max) – allowing for very-high-intensity or long efforts with low calorie intake and also allowing for use of fat fuel stores during long steady-state exercise, even at a relatively fast pace (so much for the “fat burning zone” giving you the best bang for your buck). With high-fat, low-carb intake, you can go hard and still burn tons of fat. In addition, this means that more carbohydrate stores will be available when you really need them, such as for an all-out, 100%, maximum effort.
The DNA test does not necessarily take into account your goals (e.g. breathholding, Ironman, cognition, etc.) and if your goals would benefit from ketosis, then you may want to choose it as a dietary strategy even though it could indeed be true that for FAT LOSS a higher carb intake may suit you. So it all depends on your goals. Or you could just us the supplements like ketones AND eat more carbs and get "best of both worlds".
Ketosis is an option for many people with type 2 diabetes because they still produce insulin, which helps their body maintain a safe level of ketones in the blood. If you’re considering trying ketosis or the ketogenic diet with type 2 diabetes, be sure to consult your healthcare provider first to ensure it’s safe for you. This eating approach may interfere with some types of diabetes medication or be inappropriate for you if you have certain diabetes complications, such as kidney damage.
A survey in 2005 of 88 paediatric neurologists in the US found that 36% regularly prescribed the diet after three or more drugs had failed, 24% occasionally prescribed the diet as a last resort, 24% had only prescribed the diet in a few rare cases, and 16% had never prescribed the diet. Several possible explanations exist for this gap between evidence and clinical practice.[34] One major factor may be the lack of adequately trained dietitians, who are needed to administer a ketogenic diet programme.[31]
On the ketogenic diet, carbohydrates are restricted and so cannot provide for all the metabolic needs of the body. Instead, fatty acids are used as the major source of fuel. These are used through fatty-acid oxidation in the cell's mitochondria (the energy-producing parts of the cell). Humans can convert some amino acids into glucose by a process called gluconeogenesis, but cannot do this by using fatty acids.[57] Since amino acids are needed to make proteins, which are essential for growth and repair of body tissues, these cannot be used only to produce glucose. This could pose a problem for the brain, since it is normally fuelled solely by glucose, and most fatty acids do not cross the blood–brain barrier. However, the liver can use long-chain fatty acids to synthesise the three ketone bodies β-hydroxybutyrate, acetoacetate and acetone. These ketone bodies enter the brain and partially substitute for blood glucose as a source of energy.[56]
I’m not sure if I really understand the idea of exogenous Ketones putting ones body into a state of KETOSIS, in that their own fat cells will be burned for fuel. Won’t the body just use the exogenous ketones and energy and continue to use glucose sources as well? How does taking ketones, make the body burn it’s own fat stores? I always thought that one would have to be in a state of energy deprivation for the body to actually begin to use the TG in the fat cells to generate ATP. Please let me know what I’m missing…
Once inside the mitochondrion, the dominant way that the bound fatty acids are used as fuel in cells is through β-oxidation, which cleaves two carbons off of the acyl-CoA molecule in every cycle to form acetyl-CoA.[24] Acetyl-CoA enters the citric acid cycle, where it undergoes an aldol condensation with oxaloacetate to form citric acid; citric acid then enters the tricarboxylic acid cycle (TCA), which harvests a very high energy yield per carbon in the original fatty acid.[25][26]
A lot of changes are happening in your body and you’re going to feel it! The first five to seven days can be pretty rough, but your body is getting over its dependency on sugar. During this time of transition it is essential that you supplement electrolytes. Your body is flushing out lots of water, and with that goes electrolytes. The Keto Flu can be greatly reduced if you add sodium, potassium and magnesium to your diet. Check out our supplements page for a list of electrolyte supplements we recommend. Stay on course and you’ll start feeling better in no time!
The ketogenic diet is a mainstream dietary therapy that was developed to reproduce the success and remove the limitations of the non-mainstream use of fasting to treat epilepsy.[Note 2] Although popular in the 1920s and '30s, it was largely abandoned in favour of new anticonvulsant drugs.[1] Most individuals with epilepsy can successfully control their seizures with medication. However, 20–30% fail to achieve such control despite trying a number of different drugs.[9] For this group, and for children in particular, the diet has once again found a role in epilepsy management.[1][10]
Since originally publishing this article, I’ve been asked whether elevating blood ketones with exogenous sources could trigger a ketone-induced release of insulin that would theoretically reduce hepatic ketogenesis and perhaps slow fat mobilization. This makes sense since you are putting more energy into the system in general (from exogenous ketones), so there would be less need to draw off your own fat stores.
Ben – curious about your thoughts on this. I went into ketosis (using LOTS of coconut oil) but it raised my cholesterol and doc was worried about my lp(a) level (17mg/dL on VAP) even though crp was 0.5, trigs 51 and a1c was 5.2. Advised a low fat diet. Have you seen this before with folks on a lchf/ketosis diet and is there anything to be concerned about? Off to read your coconut oil article. Thank you!
If you have a functioning pancreas that can produce insulin – i.e. you don’t have type 1 diabetes – it would be extremely hard or, most likely, impossible to get ketoacidosis even if you tried. That’s because high ketone levels result in release of insulin, that shuts down further ketone production. In other words, the body has a safety net that normally makes it impossible for healthy people to get ketoacidosis.
I'd recommend starting with glucose and hemoglobin A1C, along with a good multi like https://bengreenfieldfitness.com/multi and a fish oil like the one at greenfieldfitnesssystems.com – Anyways, I'd be happy to help you via a personal one-on-one consult. Just go to https://bengreenfieldfitness.com/coaching. and then choose a 20 or 60 minute consult, whichever you'd prefer. I can schedule ASAP after you get that.
Fairly recently, the diet was introduced as a weight-loss diet by an Italian professor of surgery, Dr. Gianfranco Cappello of Sapienza University in Rome. In his 2012 study, about 19,000 dieters received a high-fat liquid diet via a feeding tube inserted down the nose. The study showed an average weight loss of more than 20 pounds in participants, most of whom kept it off for at least a year. The researchers reported a few minor side effects, like fatigue.
“Studies have shown that the ability to stick to a diet is more important for long-term success than the type of diet that’s followed,” says Yawitz. “Keto is incredibly restrictive and is particularly tough for those who have frequent social engagements or are prone to carb cravings.” The Mediterranean diet allows you to eat carbs, like as many fruits and veggies as you want, along with whole grains. Not to mention, the Mediterranean diet has been linked to a number of other health benefits, including a lower risk of Alzheimer’s and Parkinson’s disease, certain types of cancer, and heart disease, according to the Mayo Clinic.
Meat – like grass-fed selections – and fresh veggies are more expensive than most processed or fast foods. What you spend on Keto-friendly foods will vary with your choices of protein source and quality. You can select less-expensive, leaner cuts of meat and fatten them up with some oil. Buying less-exotic, in-season veggies will help keep you within budget.

I know, I know you’d think with all these side effects I’d just give up on ketosis! but I enjoy the mental clarity and I have a lot of food sensitivities and gut and yeast problems and don’t tolerate carbs well either so I feel stuck between a rock and a hard place. Not craving what I can’t have constantly is LIFE CHANGING! (34 year old female with chronic fatigue, thin, hike for exercise).
Our bodies are incredibly adaptive to what you put into it – when you overload it with fats and take away carbohydrates, it will begin to burn ketones as the primary energy source. Optimal ketone levels offer many health, weight loss, physical and mental performance benefits.1There are scientifically-backed studies that show the advantage of a low-carb, ketogenic diet over a low-fat diet. One meta-analysis of low-carbohydrate diets showed a large advantage in weight loss. The New England Journal of Medicine study resulted in almost double the weight loss in a long-term study on ketone inducing diets.
Then there’s medium chain triglycerides (MCT’s). Most dietary fat has to be converted into water soluble molecules that then need to enter the liver via your lymph system. Your liver then converts these molecules to fatty acids and ketone bodies. But unlike most other forms of dietary fats, MCT’s can enter your liver directly without having to go through your lymph system. This means that consuming MCT’s gives your body an opportunity to quickly produce ketone bodies.
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