Peak fat oxidation was 2.3-fold higher in the LC group (1.54 ± 0.18 vs 0.67 ± 0.14 g/min; P = 0.000) and it occurred at a higher percentage of VO2max (70.3 ± 6.3 vs 54.9 ± 7.8%; P = 0.000). Mean fat oxidation during submaximal exercise was 59% higher in the LC group (1.21 ± 0.02 vs 0.76 ± 0.11 g/min; P = 0.000) corresponding to a greater relative contribution of fat (88 ± 2 vs 56 ± 8%; P = 0.000). Despite these marked differences in fuel use between LC and HC athletes, there were no significant differences in resting muscle glycogen and the level of depletion after 180 min of running (−64% from pre-exercise) and 120 min of recovery (−36% from pre-exercise).


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Because the ketogenic diet alters the body's metabolism, it is a first-line therapy in children with certain congenital metabolic diseases such as pyruvate dehydrogenase (E1) deficiency and glucose transporter 1 deficiency syndrome,[35] which prevent the body from using carbohydrates as fuel, leading to a dependency on ketone bodies. The ketogenic diet is beneficial in treating the seizures and some other symptoms in these diseases and is an absolute indication.[36] However, it is absolutely contraindicated in the treatment of other diseases such as pyruvate carboxylase deficiency, porphyria, and other rare genetic disorders of fat metabolism.[9] Persons with a disorder of fatty acid oxidation are unable to metabolise fatty acids, which replace carbohydrates as the major energy source on the diet. On the ketogenic diet, their bodies would consume their own protein stores for fuel, leading to ketoacidosis, and eventually coma and death.[37]
That’s right: it turns out that if I could go back and do my year of strict ketosis again, I would do everything you’ve going to discover below. If I had done that, I would have avoided all the uncomfortable, unhealthy issues I experienced when I was eating a high-fat diet, and I would have gotten all the benefits with none of the harm. As a matter of fact, in the past 30 days, as I’ve begun a new journey into ketosis, I am now implementing the exact four methods you’re about to discover.
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.
Long-term disruption of menstruation can bring on serious side effects, including low bone density. “This is because estrogen is very important to bone health,” says Yawitz. “Studies have also found prolonged menstrual irregularity to increase risk for cardiovascular disease, depression, anxiety, and sexual dysfunction. It’s important to contact your ob-gyn if your cycles become irregular or if you stop having periods.”
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!
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 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.

“Certainly, the quality of fat counts,” says Yawitz. “There’s a big difference nutritionally between bacon and almonds. As much as possible, people set on the keto diet should emphasize plant-based, unsaturated fats like nuts, seeds, olive oil, and avocado, which have even been shown to protect the heart.” If you have high cholesterol or other risk factors for heart disease, you should speak with your doctor before beginning the keto diet. This is because the diet may — but doesn't have to — include large amounts of saturated fat. Some studies have shown increases in cholesterol and triglycerides in people following the diet, while other research reveals that the keto diet may actually decrease heart disease risk as well as saturated fat intake.
The ketogenic diet is a medical nutrition therapy that involves participants from various disciplines. Team members include a registered paediatric dietitian who coordinates the diet programme; a paediatric neurologist who is experienced in offering the ketogenic diet; and a registered nurse who is familiar with childhood epilepsy. Additional help may come from a medical social worker who works with the family and a pharmacist who can advise on the carbohydrate content of medicines. Lastly, the parents and other caregivers must be educated in many aspects of the diet for it to be safely implemented.[5]

I am not an athlete. I am a mid 30’s male with a sedentary lifestyle. I am 5’10” and 250lbs. I have mild hypertension, high triglycerides, and pre-diabetes. I have eaten whatever I want and as much as I want for years. I have recently started walking/jogging 3-4 times a week, taking fish oil, and eating significantly less carbs plus added fish and steak. Is this diet appropriate and safe for me?
I talk about that quite a bit here :https://bengreenfieldfitness.com/2015/09/things-your-pee-can-tell-you-about-your-body/

I tried a lot of shit to get thin. I used to eat exactly seven almonds to stave off hunger before bed. I finished my last meal at 4pm and my breakfast at noon. I passed on croutons. I worshipped fitness influencers so much that my ex photoshopped a photo of Tim Ferriss and I cooking together. I swore by kettlebelling. I peed on test strips at the drug test clinic I worked at to measure my ketone levels. I put MCT oil and butter in my coffee and avoided bread for nearly three years. I thought about making an Instagram of myself dumbbell lunging on a weight bench with the reps in the description. To some people, I was #goals.

In the US especially, coconut oil and MCT oil manufacturers are legally allowed to claim that lauric acid is an MCT because chemists named it that way, even though it does not act like other true biological MCT oils. If you are relying on plain coconut oil or “MCT-labeled” oil to get enough useful MCTs, think again and check the label: odds are you’re getting very few of the potent, ketogenic shorter chain MCTs (also known as “C8” and “C10”), and instead getting mostly cheaper but ineffective lauric acid.


Hi Kelly, All packaged foods will have a nutrition label that list the macros per serving, including fat, protein and cabrohydrates. Net carbs, which is what most people look at for low carb and keto, are total carbs (the amount on the label) minus fiber and sugar alcohols, as explained in the article above. I have a low carb food list here that gives you a full list of all the foods you can eat, and the net carbs in each. You can also sign up above to be notified about the meal plans, which are a great way to get started.
Amazing article – gonna have to print it and read it again. To much to break down in one sitting. Thanks Ben – you’ve pulled together so much insight and references that’s given me greater confidence and conviction. I’m 50 and use to be super active and a seasoned athlete but after a few ‘mid life surgical interventions’ I had to find a better way… Ketogenics has been that for me… no more inflammation… I can’t tell you how great it’s been to be pain free! Keep leading from the front.
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
I’m missing one key-step in this whole process … I understand (vaguely) how to get into ketosis via diet, starvation, or supplementation. But, my confusion really is with the supplementation method (such as XCT Oil, for example). If I supplement with these to get into ketosis quicker, but haven’t significantly altered to a high-fat diet, won’t I just shift back into glucose-use as soon as I burn out the supplemented ketones?? like within minutes / hours?
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.

Reduced hunger. Many people experience a marked reduction in hunger on a keto diet. This may be caused by an increased ability of the body to be fueled by its fat stores. Many people feel great when they eat just once or twice a day, and may automatically end up doing a form of intermittent fasting. This saves time and money, while also speeding up weight loss.


Selecting the right food will be easier as you become accustomed to the Keto approach. Instead of lean meats, you’ll focus on skin-on poultry, fattier parts like chicken thighs, rib-eye steaks, grass-fed ground beef, fattier fish like salmon, beef brisket or pork shoulder, and bacon. Leafy greens such as spinach, kale and lettuce, along with broccoli, cauliflower and cucumbers, make healthy vegetable choices (but you’ll avoid starchy root foods like carrots, potatoes, turnips and parsnips). You can work in less-familiar veggies such as kohlrabi or daikon.


My Husband and I started doing Keto July 2018. We got over weight after we got out of the Marine Corps. It has been hard to workout because I became disabled, but my diet was not good. After our friend Amber recommended your site and support group, we found a lot of helpful information to get us started on a successful journey. So far it’s been one month and we have lost 18 pounds each!
Take coconut oil for example. The coconut oil industry loves to market the idea that relatively inexpensive and abundant coconut oil is a great source of MCTs because it’s “62% MCT oil”, but the problem is that studies show you can’t get many useful ketogenic MCT’s from just eating coconut oil or even most brands of “MCT oil”, which are often is diluted with lauric acid, a cheap, hugely abundant part of coconut oil that is typically marketed as an MCT oil.

Under these circumstances, as soon as the body’s limited reserves of glucose starts to run out, your entire body switches its fuel supply to run almost completely on fat. The levels of the fat-storing hormone insulin levels become very low, and fat burning increases dramatically. You thus get easy access your fat stores, and can burn them off. This is great for losing excess weight. Studies prove that keto diets result in more weight loss, faster. There are also more potential benefits.

On a low carb or ketogenic diet my fasting blood sugar is 90-120. I think it may get higher the lower carb I go. Most internet sources say don’t worry about it, worry about your Ha1c. Is this insulin resistance? Anyone have better information? If I do a water fast my morning blood sugar will go down and down each day, til it reaches about 50 in 4 days. But as soon as I start eating it pops right back up.


If you’re following the keto diet, you will need protein, but you should limit your intake to about 20 percent of your total daily calories. (1) This is important because when you consume more protein than you need, your body converts the excess protein into carbs through a process called gluconeogenesis. This process pushes your body out of ketosis.

Decades later, when low carb became the best thing since sliced bread, people were calling it the Air Force Diet and the Drinking Man’s; Atkins and Paleo; Comet and Cupid. Then, in 2016, podcaster and MMA commentator Joe Rogan discussed keto once on his show and his loyal following of fitness enthusiasts and life optimizers took it and ran (especially in the mornings, to increase fat burning during the fasting state). 
My question is: what if I want to be in ketosis for all the reasons mentioned in the Life Extension article and because I don't feel a strong urge to eat in between meals when I go lower carb and if I up carb intake I get hungrier more frequently and get urges . . . BUT on the flip side, I don't seem to digest fat all that well(dairy in particular is a no-no) and constipation is an issue and starchy carbs seem to help with that. It's a bit of a catch-22.
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