Even though star fruit is another fruit that some people don’t think to add to their grocery list, it’s worth a try if you’re on keto and want to satisfy your sweet tooth. A ½-cup serving of cubed star fruit contains about 2.6 g of net carbohydrates, plus 1.8 g of fiber and 2.6 g of sugar. It’s also low in calories and has 88 mg of potassium (1.9 percent DV) and 22.7 mg of vitamin C (38 percent DV). 

You also get incredible gains in metabolic efficiency when you use fat as a primary source of fuel – especially when doing high-intensity interval training – with this one-two combo causing potent 3–5 percent decreases in the oxygen cost of exercise, which is extremely significant. Translated into real- world numbers, this increased fat utilization from carbohydrate restriction and high-intensity interval training would allow you to pedal a bicycle at a threshold of 315 watts, whereas a high-carbohydrate, aerobic-only program (the way most people train) would allow for only 300 watts. Talk to any cyclist and you’ll find out that an 15 extra watts of power is huge in a sport like cycling, and something most cyclists train years and years to achieve.
Hi Ben, great article. I have been a keto-adapted athlete for over 2 years, all through nutrition (65/25/10). I have recently discovered UCAN, KetoOS and MAP Aminos. So, here’s my question: If I am going out for a 4-hour ride, and I want to fuel myself just on these supplements and my body’s natural fat stores, how and in what order should I take them? If I take them all together, will the aminos in the KetoOS interfere with MAP Aminos? Or should I just make a mix of the UCAN and KetoOS in 10oz of water and use it to wash back my 6 MAP tablets, 15-mins before my ride? Thanks for your advice!
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.
Remember how important it is to measure ketone blood levels accurately? Same goes for food tracking. A food tracking app, like MyFitnessPal, provides insight into macronutrient intake and thus the ability to tweak the diet to achieve ketosis. Tracking diet (inputs) and measuring ketones levels (outputs) delivers the best shot at optimizing the keto diet plan.
The ketogenic diet is indicated as an adjunctive (additional) treatment in children and young people with drug-resistant epilepsy.[26][27] It is approved by national clinical guidelines in Scotland,[27] England, and Wales[26] and reimbursed by nearly all US insurance companies.[28] Children with a focal lesion (a single point of brain abnormality causing the epilepsy) who would make suitable candidates for surgery are more likely to become seizure-free with surgery than with the ketogenic diet.[9][29] About a third of epilepsy centres that offer the ketogenic diet also offer a dietary therapy to adults. Some clinicians consider the two less restrictive dietary variants—the low glycaemic index treatment and the modified Atkins diet—to be more appropriate for adolescents and adults.[9] A liquid form of the ketogenic diet is particularly easy to prepare for, and well tolerated by, infants on formula and children who are tube-fed.[5][30]
When HVMN Ketone was tested in mice, they performed 38% better on a maze solving challenge, so it's possible there may be a cognitive boost for humans also.9 While following a ketogenic diet, you avoid the energy peaks and troughs that come from quick-energy carbs. Producing ketones from stored body fat provides the brain with a steady, sustainable supply of fuel.

For example, a key component of safe and lasting fat loss is your capability to tap into your body’s own storage fat for energy. This access to fat cannot happen if your body is constantly drawing on carbohydrate reserves and blood glucose for energy. In the type of moderate- to high-carbohydrate diets you’ve learned are widely recommended by prevailing nutrition science, not only does the utilization of fat for energy become far less crucial (since you’re constantly dumping readily available sugar sources into your body), but your metabolism never becomes efficient at using fat. There is a growing body of evidence proving that a high-fat, low-carbohydrate diet results in faster and more permanent weight loss than a low-fat diet. Furthermore, appetite satiety and dietary satisfaction significantly improve with a high-fat, low-carbohydrate diet that includes moderate protein.


Thanks for all of the great info!! I have Hashimoto’s and would really like to try a high fat/low carb diet. You mentioned that this might not be a good option for people with thyroid issues. How do you recommend I modify my diet to lose weight taking into consideration the Hashimoto’s. I take Westhroid, a non-synthetic thyroid supplement to help with my sluggish thyroid. Thanks so much for any advice you can give me. :)
An interview with University of Florida researcher and scientist Dominic D’ Agostino. In that episode, “A Deep Dive Into Ketosis: How Navy Seals, Extreme Athletes & Busy Executives Can Enhance Physical and Mental Performance With The Secret Weapon of Ketone Fuel“, Dominic highlights his research into the use of ketones to enhance breathhold time and reduce the brain’s requirements for oxygen.
Some people group tomatoes with vegetables, but a tomato is actually a fruit. Low in fat but also carbs (with just 2.4 g of net carbs per ½ cup), tomatoes are also keto-friendly. The same serving size of tomatoes contains 2.4 g of sugar and 16 calories. Among their health benefits, tomatoes contain lycopene, which research suggests may help prevent heart disease.
In Asia, the normal diet includes rice and noodles as the main energy source, making their elimination difficult. Therefore, the MCT-oil form of the diet, which allows more carbohydrate, has proved useful. In India, religious beliefs commonly affect the diet: some patients are vegetarians, will not eat root vegetables or avoid beef. The Indian ketogenic diet is started without a fast due to cultural opposition towards fasting in children. The low-fat, high-carbohydrate nature of the normal Indian and Asian diet means that their ketogenic diets typically have a lower ketogenic ratio (1:1) than in America and Europe. However, they appear to be just as effective.[54]
But wait, there’s one loophole. Have polycystic ovary syndrome (PCOS)? Then the keto diet may help regulate your periods. “Women with PCOS have high insulin levels, which cause sex hormone imbalances,” notes Yawitz. In a small study published in the journal Nutrition & Metabolism, subjects with PCOS following a ketogenic diet for six months noted improvements in their menstrual cycles — and a small number of women became pregnant, overcoming previous infertility obstacles. “This study was very small, so we can’t make recommendations for all women with PCOS based on its findings,” says Yawitz. “And really, any diet that leads to weight loss should help in PCOS.”
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!!!
Sensational article. I am experimenting with a low carb diet, high fats and moderate protein. I am not keeping strict notes on what I eat but I cut out almost all fruit and I eat eggs, spinach, kale, chard, avacados, hard cheese, walnuts (raw organic) and grass fed meet and butter. I take about 25-30ml of Brain Octane straight a day. I take your probiotic and colostrum (I need to get more regular) and I consume bone broth four days a week. I am looking to live longer and be healthier during that long life. In the short term I want to be smarter and be able to handle stress better. I would also love to avoid cancer and drop a deuce every day. My question is: Is there a point of carb consumption where even combining it with exogenous ketones using your recommendations it would be less effective or cause negative outcomes? Could one consume all the cards and sugar one wanted and use the supplements and still be getting into ketosis and reaping the benefits?
You said you saw Dr. Jeff Volek at UCONN. I am interested in ketosis to help me with my M.S. I still have questions related to M.S. and not so much as it effects on athletes. I do live in CT, but was unable to locate Dr. Volek at either the Storres or Farmington campus. Would you be able to give me either his e-mail address or telephone number so that I can contact him directly? Your help would be greatly appreciated.

Let’s talk about a keto side effect that may not be so sexy: constipation. “Many of the richest sources of fiber, like beans, fruit, and whole grains are restricted on the ketogenic diet,” says Clark. “As a result, ketogenic eaters miss out on the benefits of fiber-rich diet such as regular laxation and microbiome support. The microbiome has been implicated in everything from immune function to mental health.” Indeed, in a long-term study in the Journal of Pediatrics in April 2015, constipation was noted as a very common side effect in children receiving ketogenic diets for epilepsy treatment.
"Many of the richest sources of fiber, like beans, fruit, and whole grains are restricted on the ketogenic diet," registered dietician Edwina Clark told Everyday Health. "As a result, ketogenic eaters miss out on the benefits of fiber-rich diet such as regular laxation and microbiome support. The microbiome has been implicated in everything from immune function to mental health."
It is very interesting to read about the keto/low card diet.I love to change my lifestyle as I an TYPE 2 Diabetic.I subscribed for a free printable low carb meal .The initial email stated that that I will receive an email for instructions to access the members area .Your free download will be there.However it is very deceiving ,I never got the 2nd email with instructions which is frustrating and not good .Hopefully this is not a way to get us to pay to get the printable version.
What is the link between ketones and diabetes? Ketone is a chemical produced by the body when fats are broken down for energy. Ketone testing is important for people with diabetes, because high levels can lead to diabetic ketoacidosis (DKA), when acid levels become too high in the blood and the person loses consciousness. Find out when and why to do ketone testing. Read now

"The keto diet is primarily used to help reduce the frequency of epileptic seizures in children. While it also has been tried for weight loss, only short-term results have been studied, and the results have been mixed. We don't know if it works in the long term, nor whether it's safe," warns registered dietitian Kathy McManus, director of the Department of Nutrition at Harvard-affiliated Brigham and Women's Hospital.

“Loss of muscle mass as we age has a number of serious consequences,” notes Clark. “Muscle is metabolically active and helps boost daily energy expenditure and mitigate age-related weight gain.” Losing muscle mass can also decrease functional strength and heighten the risk of falls, notes Clark. Falls are the top cause of death from injury in older populations, according to the Institute of Medicine Division of Health Promotion and Disease Prevention.


I am curious if someone takes any or too much MCT oil (5-10 tablespoons/day) or Exogenous Ketones will the liver slow/stall or shut off endogenous ketone production as you are providing the ketones exogenously and thereby you may NEED to supplement ketones to maintain ketone levels or you may suffer a short term ketone deficit while the liver adjusts to making them on its own again. A parallel I am thinking of is exogenous testosterone supplementation and the hypothalamus/endocrine system slowing/stopping endogenous testosterone production (seen in bodybuilders).
Remember how important it is to measure ketone blood levels accurately? Same goes for food tracking. A food tracking app, like MyFitnessPal, provides insight into macronutrient intake and thus the ability to tweak the diet to achieve ketosis. Tracking diet (inputs) and measuring ketones levels (outputs) delivers the best shot at optimizing the keto diet plan.
In fact, most folks have enough stored body fat to fuel aerobic activity for days and days without running out of energy. For example, a 150 pound dude at a hot, sexy and ripped at 8% body fat still carries 12 pounds of storage fat – which at 3500 calories per pound of fat can easily liberate 42,000 calories of useable fuel for exercise. You’ve got those same thousands of calories sitting around your waist, abs, hip, butt and thighs – just sitting there, waiting to be burnt.
A: The amount of weight you lose is entirely dependent on you. Obviously adding exercise to your regimen will speed up your weight loss. Cutting out things that are common “stall” causes is also a good thing. Artificial sweeteners, dairy, wheat products and by-products (wheat gluten, wheat flours, and anything with an identifiable wheat product in it).

Although many hypotheses have been put forward to explain how the ketogenic diet works, it remains a mystery. Disproven hypotheses include systemic acidosis (high levels of acid in the blood), electrolyte changes and hypoglycaemia (low blood glucose).[19] Although many biochemical changes are known to occur in the brain of a patient on the ketogenic diet, it is not known which of these has an anticonvulsant effect. The lack of understanding in this area is similar to the situation with many anticonvulsant drugs.[56]
Great post!! I’m a 41 year old Master CrossFit athlete, been in keto / LCHF Primal lifestyle for the past 9 years. I feel that my performance has improved a lot and continues to improve pretty significantly. I was a top 200 Master Open Qualifier on 2016 and 2017 and I’m usually on the podium of local competitions so my performance is really not bad…and I’m totally fat adapted. I follow sort of a TKD where I sometimes eat carbs at night during the week, but never above 100g so It doesn’t even kick me out of ketosis due to activity level. I’ve been playing with some measurements and I noticed that my BG reading after high intensity training sessions is really high (up to 180mg/dl). But it goes down fast (sometimes it goes down to 50mg/dl but I show no side effect of hypo, function completely normal). From my research, the high glucose post high intensity is normal and due to the stressful response of the exercise and also because my liver is producing the glucose from gluconeogeneses to provide it for the workouts, when needed. This only happens when the workouts are long, above 30 minutes.
Considered a symptom of the keto flu, your breath on this diet often smells fruity at first. This is because acetone is a by-product of ketosis and is eliminated mostly through the lungs and the breath, according to a study in the journal International Journal of Environmental Research and Public Health in February 2014. Acetone is a type of ketone known for having a fruity aroma in smaller concentrations. “It’s hard to say exactly how long it will last as it depends on the person, but it’s common for someone to experience this side effect for a few weeks,” says Asche.
The ketogenic diet is not a benign, holistic, or natural treatment for epilepsy; as with any serious medical therapy, complications may result.[28] These are generally less severe and less frequent than with anticonvulsant medication or surgery.[28] Common but easily treatable short-term side effects include constipation, low-grade acidosis, and hypoglycaemia if an initial fast is undertaken. Raised levels of lipids in the blood affect up to 60% of children[38] and cholesterol levels may increase by around 30%.[28] This can be treated by changes to the fat content of the diet, such as from saturated fats towards polyunsaturated fats, and if persistent, by lowering the ketogenic ratio.[38] Supplements are necessary to counter the dietary deficiency of many micronutrients.[18]

They mimic ketosis, to answer your question in short. Best to get fat adapted and use ketones to get the best of both worlds and to enhance fat burning abilities. They will allow you to use glucose and fatty acids simultaneously, yes. 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.
I see a lot of people say that ketosis is great for insulin sensitivity. BUT, in my experience ketosis causes physiological insulin resistance whereby the muscles and liver are sparing glucose for the brain. Hence, glucose tolerance actually goes down during ketosis. As such, is it possible that post workout carbs could do a lot more damage than they would on a non-ketogenic diet? Or maybe, as Kiefer suggests, glucose uptake post workout is not moderated by insulin at all i.e. muscles soak up glucose regardless of their insulin sensitivity? Or maybe cyclical ketosis doesn’t allow liver glycogen to get low enough to trigger physiological insulin resistance?
Burns fat: You can drop a lot of weight — and quickly — on the keto diet.[3] Ketones suppress ghrelin — your hunger hormone — and increase cholecystokinin (CCK), which makes you feel full.[4] Reduced appetite means it’s easier to go for longer periods without eating, which encourages your body to dip into its fat stores for energy. Learn more here about the keto diet and weight loss. 
The same goes for people with type 2 diabetes. While some preliminary research suggests the keto diet may be safe and effective for certain people with type 2 diabetes, there’s still the risk for low blood sugar, especially for those on insulin, and the keto diet omits certain food groups known to benefit those with this disease. For example, a study published in September 2016 in the journal Nutrients highlights the importance of whole grains for helping to control weight as well as episodes of high blood sugar. Whole grains are off-limits on the ketogenic diet.
No offense brother, but this whole article is a big selling advertisement. The health benefits of a “low – carb, high – fat” diet are well known and proven. I directly blame nutritionists, like yourself, for the fact that ~70% of American is considered obese now, not fat, obese. And the fact that Heart Disease is the number 2 killer in America now, second only to cancer.
First, a little background: Eric Westman, MD, director of the Duke Lifestyle Medical Clinic, explained to Health in a previous interview that in order to successfully follow the keto diet, you need to eat moderate amounts of protein, reduce your carb intake, and increase fats. When you reduce your carb consumption, your body turns to stored fat as its new fuel source—a process called ketosis. To stay in ketosis, followers of the keto diet must limit their carbs to 50 grams a day, Dr. Westman says.
I’ve been experimenting with MCT Oil Brain Octane. I have one questions. I’ve been eating about 20 – 25 gr. of carbs per day on a high fat, medium protein diet. I’m measuring ketones in the morning before taking the MCT and after. I’ve been taking btw. 1-2 tbsp of MCT Brain Octane with butter (Bulletproof coffee) – I measure again after 30 min., 1hr, 2 hrs. and don’t see a raise in my blood ketones. Anything I’m missing, would love to hear your thoughts, Ben. – Thx I’m measuring with Precision Xtra and Ketonix Red.
There are so many tricks, shortcuts, and gimmicks out there on achieving optimal ketosis – I’d suggest you don’t bother with any of that. Optimal ketosis can be accomplished through dietary nutrition alone (aka just eating food). You shouldn’t need a magic pill to do it. Just stay strict, remain vigilant, and be focused on recording what you eat (to make sure your carb and protein intake are correct).
The ketogenic diet is calculated by a dietitian for each child. Age, weight, activity levels, culture, and food preferences all affect the meal plan. First, the energy requirements are set at 80–90% of the recommended daily amounts (RDA) for the child's age (the high-fat diet requires less energy to process than a typical high-carbohydrate diet). Highly active children or those with muscle spasticity require more food energy than this; immobile children require less. The ketogenic ratio of the diet compares the weight of fat to the combined weight of carbohydrate and protein. This is typically 4:1, but children who are younger than 18 months, older than 12 years, or who are obese may be started on a 3:1 ratio. Fat is energy-rich, with 9 kcal/g (38 kJ/g) compared to 4 kcal/g (17 kJ/g) for carbohydrate or protein, so portions on the ketogenic diet are smaller than normal. The quantity of fat in the diet can be calculated from the overall energy requirements and the chosen ketogenic ratio. Next, the protein levels are set to allow for growth and body maintenance, and are around 1 g protein for each kg of body weight. Lastly, the amount of carbohydrate is set according to what allowance is left while maintaining the chosen ratio. Any carbohydrate in medications or supplements must be subtracted from this allowance. The total daily amount of fat, protein, and carbohydrate is then evenly divided across the meals.[37]
Children who discontinue the diet after achieving seizure freedom have about a 20% risk of seizures returning. The length of time until recurrence is highly variable, but averages two years. This risk of recurrence compares with 10% for resective surgery (where part of the brain is removed) and 30–50% for anticonvulsant therapy. Of those who have a recurrence, just over half can regain freedom from seizures either with anticonvulsants or by returning to the ketogenic diet. Recurrence is more likely if, despite seizure freedom, an electroencephalogram shows epileptiform spikes, which indicate epileptic activity in the brain but are below the level that will cause a seizure. Recurrence is also likely if an MRI scan shows focal abnormalities (for example, as in children with tuberous sclerosis). Such children may remain on the diet longer than average, and children with tuberous sclerosis who achieve seizure freedom could remain on the ketogenic diet indefinitely.[46]
Western diets are high in carbohydrates, leading to high blood sugar levels, whereas the ketogenic diet enforces a small amount of carbs to be consumed. It can take some weeks of keto dieting to reach increased levels of blood ketones. For others, after 2 - 4 days of low-carbohydrate, high-fat ketogenic dieting, ketone levels in the blood can increase to ~1 - 2 mM, achieving ketosis.5
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