A ketogenic diet (also known as “nutritional ketosis”) is a high-fat, adequate-protein, low-carbohydrate diet. On a ketogenic diet, your brain uses ketones (a byproduct of your fat-burning metabolism) for fuel, instead of glucose.[1] Since humans can burn either glucose or ketones for energy, this change is possible to make, although there is some controversy surrounding ketogenic diets regarding both their efficacy and health benefit.[2] Ketosis keeps your body in a “fasting” or starvation metabolism, and consequently encourages weight loss by burning off fat reserves. While the shift to a ketogenic diet can be difficult initially, you should begin to see results after a few weeks.
I prescribe nutritional ketosis for my patients with brain and focus issues, such as: epilepsy, attention deficit, brain fog, traumatic brain injury, memory issues, mild cognitive impairment, Parkinson’s disease, and Alzheimer’s disease (including patients with one or two copies of the genes for Alzheimer’s, called ApoE4). Most of my patients on keto say they feel smarter, sharper, and more focused—and some may lose weight (fat) as a result of using ketones as fuel.
A CKD on the other hand is a diet where you will eat a minimum amount of carbohydrates per day (that 30-50 gram number) and then on the weekend (or at a time that is appropriate for you) do a large 'carb-up' phase where you will eat a large amount of carbohydrates in an effort to refill your muscle glycogen stores so you can continue to workout the coming week.
The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The Nutrition Source does not recommend or endorse any products.
“I discovered the ketogenic diet in 2017 and since then I have come to truly believe it is the metabolic and nutritional pathway to overall health. Hippocrates once stated, ‘All disease begins in the gut” and I now truly believe the right food can cure. I am now discouraging patients from undergoing bariatric surgery too soon and advising them to try the keto diet first. Diet Doctor gives people the knowledge they need. It is a place where everyone can go to learn and have fun with this nutritional approach.”
Keto runs counter to many of the low-fat diet fads of the 1980s and 1990s: It actually emphasizes fat. “That is hard to comprehend because we don’t eat anything that’s pure fat, says Kristen Mancinelli, RD, author of The Ketogenic Diet. “We don’t eat a stick of butter or a spoonful of olive oil or even a nice cup of lard. That would be unpleasant, so we really have a hard time wrapping our heads around this concept of the ketogenic diet.”

Anecdotally speaking, people do lose weight on the keto diet. Heather Wharton, a 35-year-old business relationship manager from Tampa, Florida, lost 140 pounds since starting the keto diet in January 2016: “I plan on being on the keto diet for the rest of my life,” says Wharton. “My husband and I consider ourselves to be food addicts, and the keto diet is what we use as a form of abstinence from trigger foods that have sugar and other carbohydrates." A typical day of eating for Wharton includes coffee with a protein supplement, a cup of unsweetened cashew milk, cauliflower rice with ground turkey and liquid aminos (a carb-free substitute for soy sauce), spinach, six slices of turkey bacon, six eggs, and a little salsa.
Dr. Josh Axe, DNM, DC, CNS, is a doctor of natural medicine, clinical nutritionist and author with a passion to help people get well using food as medicine. He’s the author of the books “Eat Dirt: Why Leaky Gut May Be the Root Cause of Your Health Problems,” “Essential Oils: Ancient Medicine” and the upcoming “Keto Diet: Your 30-Day Plan to Lose Weight, Balance Hormones, Boost Brain Health, and Reverse Disease” (February 2019, published by Little, Brown Spark). He’s a co-founder of Ancient Nutrition, a health company where the mission is to restore health, strength and vitality by providing history’s healthiest whole food nutrients to the modern world.
This is a diet that requires a fair amount of attention to macronutrient quantities in order to work. Unlike the Atkins diet, which only restricts carbs, the ketogenic diet also restricts protein based on your activity level, so that extra protein doesn’t get converted into glucose. When people first go on nutritional ketosis, they sometimes focus on getting their carbs super low (i.e., less than 20 grams per day), and that can cause hormone and mood problems, especially in women. They make up the difference with too much protein, which then converts into sugar. So if you over-restrict carbs and eat too much protein, ketosis may not work. It’s not just a certain amount of carbs you want to target, but the right combination of fat, carbs, and protein for YOU.
Keto flu symptoms and side effects can include feeling tired, having difficulty sleeping, digestive issues like constipation, weakness during workouts, being moody, losing libido and having bad breath. Fortunately, these side effects don’t affect everyone and often only last for 1–2 weeks. (And yes, you CAN build muscle on keto.) Overall, symptoms go away as your body adjusts to being in ketosis.
The keto diet is a high-fat and low-carb (HFLC) diet. I would actually describe it as extremely low-carb—you're allowed to eat just 20 grams in a day. Some people on keto follow a net-carb plan (you can subtract the grams of fiber from a food's total carbs) and you're allowed to eat more carbs in a day. For my 30-day diet and for the sake of simplicity, I stuck with total carbs.
What's more, it's especially important to make sure your diet is well-planned when you're eating keto-style, because the foods you can choose from are limited. In addition to checking in with a dietitian if you're able, Stefanski recommends that you "talk to your doctor and make sure she or he is aware that you'll be starting a diet that completely changes how your body metabolizes energy." You might also want to check your most recent bloodwork levels for things such as cholesterol, vitamin D, and other indicators of health because these can change while on keto. That's because for some people, a prolonged keto diet can result in certain nutritional deficiencies or even high cholesterol. But most experts will tell you that the ketogenic diet is not a permanent lifestyle change (as could be the case for something like the 80/20 approach to eating or a Mediterranean eating style).
Dinner: In a small sauce pan bring 2-3 cups of water to the boil. Cook a large egg in rolling boil for 5 minutes, then transfer to ice bath (a bowl with cold water and ice cubes in it). Wash and spin dry butter lettuce, top with sliced avocado and hemp seed. Serve soft boiled egg with cherry tomatoes, butter lettuce salad and mayonnaise as dressing.
“The low-carb, high-fat diet has re-energized my clinical interest in the treatment of diabetes, obesity, and other chronic conditions relating to insulin resistance. Guiding my patients on their journey to reclaiming their health, wellness, and vitality with the prescription of real food brings me the utmost joy. Witnessing the transformative impact of this lifestyle has given me hope for the future health of our patients and communities.”
While it may be new to you, the keto diet has actually been around since the 1920’s, when the Mayo Clinic reported its effectiveness for helping epilepsy (that is still the case). Since then, there’s strong evidence that the keto diet helps with weight loss as well as type 2 diabetes, prediabetes, and metabolic syndrome, says Jeff Volek, Ph.D., RD, professor in the department of Human Sciences at The Ohio State University in Columbus, Ohio and co-author of The Art and Science of Low Carbohydrate Living.
When your body goes into ketosis, it will start to produce by-products called ketones. This includes acetone—yes, the same chemical found in nail polish remover, which your body actually naturally makes on its own, according to a 2015 review of research. Because acetone is a smaller molecule, it tends to make its way into your lungs. You’ll eventually exhale them out, resulting in “keto breath.” Your mouth might also have a metallic taste, but it won’t last forever as you adjust to the diet. Just be diligent about brushing your teeth!
It has been repeatedly found that in the long-term, all diets with the same calorific value perform the same for weight loss, except for the one differentiating factor of how well people can faithfully follow the dietary programme.[27] A study comparing groups taking low-fat, low-carbohydrate and Mediterranean diets found at six months the low-carbohydrate diet still had most people adhering to it, but thereafter the situation reversed: at two years the low-carbohydrate group had the highest incidence of lapses and dropouts.[27] This may be due to the comparatively limited food choice of low-carbohydrate diets.[27]
In theory, a ketogenic diet that increases carbohydrate loads for cardio exercise seems perfect. However, the side effects of a ketogenic diet can include dehydration, malnutrition and constipation. According to the Mayo Clinic website, ketogenic plans also can lead to kidney stones. In addition, the ketogenic diet does not give you the nutrition you need to be healthy. Instead, try cutting portion sizes and counting calories; this also can force your body to burn fat while still providing you with balanced nutrition, including proteins, carbohydrates, fiber and fat. As with any diet, you should discuss a ketogenic diet with your doctor. 

Aude, Y., A. S, Agatston, F. Lopez-Jimenez, et al. “The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat: A Randomized Trial.” JAMA Internal Medicine 164, no. 19 (2004): 2141–46. doi: 10.1001/archinte.164.19.2141. jamanetwork.com/journals/jamainternalmedicine/article-abstract/217514.
A ketogenic diet also has been shown to improve blood sugar control for patients with type 2 diabetes, at least in the short term. There is even more controversy when we consider the effect on cholesterol levels. A few studies show some patients have increase in cholesterol levels in the beginning, only to see cholesterol fall a few months later. However, there is no long-term research analyzing its effects over time on diabetes and high cholesterol.
Great point – the literature shows that ketogenic macro splits are very protein sparing for weight loss and the body will typically burn fat and glucose and spare lean mass. Dr. Jason Fung makes the analogy that it would be like stacking firewood for the winter and then when winter hits, deciding not to use the firewood and instead use the living room couch!
“Through my 31 years in primary care, I have witnessed the growing waistlines and blood sugar levels of my patients. Seeing that the “eat less, move more” advice was failing them, I moved to a low-carb, high-fat approach eight years ago. This has produced great results in my patients. I am able to manage many medical issues without resorting to medications. This new approach has revitalized my practice. I feel like I can finally really help my patients.”
Katherine Arvesen, RDN, who in private practice in Plano, Texas, also notes that the study was not randomized and controlled, which is the gold standard for medical research to minimize error and bias. In this study, the patients were their own controls, meaning their results were compared with their own baseline (starting) measurements, not with the results of a control group.
Wondering how many carb foods you can eat and still be “in ketosis”? The traditional ketogenic diet, created for those with epilepsy consisted of getting about 75 percent of calories from sources of fat (such as oils or fattier cuts of meat), 5 percent from carbohydrates and 20 percent from protein. For most people a less strict version (what I call a “modified keto diet”) can still help promote weight loss in a safe, and often very fast, way.
A ketogenic diet (also known as “nutritional ketosis”) is a high-fat, adequate-protein, low-carbohydrate diet. On a ketogenic diet, your brain uses ketones (a byproduct of your fat-burning metabolism) for fuel, instead of glucose.[1] Since humans can burn either glucose or ketones for energy, this change is possible to make, although there is some controversy surrounding ketogenic diets regarding both their efficacy and health benefit.[2] Ketosis keeps your body in a “fasting” or starvation metabolism, and consequently encourages weight loss by burning off fat reserves. While the shift to a ketogenic diet can be difficult initially, you should begin to see results after a few weeks.
The information you share, including that which might otherwise be Protected Health Information, to this site is by design open to the public and is not a private, secure service. You should think carefully before disclosing any personal information in any public forum. What you have written may be seen, disclosed to, or collected by third parties and may be used by others in ways we are unable to control or predict, including to contact you or otherwise be used for unauthorized or unlawful purposes. As with any public forum on any site, this information may also appear in third-party search engines like Google, MSN, Yahoo, etc. Your use of this site is governed by Harvard University and its affiliates Terms of Use located at www.health.harvard.edu/privacy-policy and may be amended from time to time.
A review of multiple studies in the journal Nutrients found that ketogenic diets are connected to significant reductions in total cholesterol, increases in “good” HDL cholesterol levels, dips in triglycerides levels and decreases in “bad” LDL cholesterol; there are questions as to whether diets high in saturated fat negate these benefits. The same paper reports that a ketogenic may slightly reduce blood pressure, but science is still very scant on this point.
“I recommend LCHF nutrition to all my patients to shift their metabolism to a more beneficial state. This nutrition is often enough to reverse diseases like obesity, diabetes and fatty liver disease, improving the health and quality of life of my patients. In my experience, other medical interventions also become much more efficacious. I recommend the Diet Doctor website, due to its panel of experts, to all my patients to make their transition easier.”
If you do try the diet outside of medical supervision, Kizer says it’s important to test your urine with urinalysis ketone test strips to ensure your ketone levels don’t become dangerously high. Ketone urine test strips are also used by people with diabetes to determine if they’re at risk for ketoacidosis (DKA), a life-threatening complication that occurs when an individual doesn’t have enough insulin in their body. (Healthy ketosis is considered 0.5 to 3.0 mM blood ketones.)
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]
Stock up: Jet.com's new City Grocery service (available in select markets) makes it easy to ensure you always have keto-friendly veggies in the fridge. We love their delivery scheduling tool; simply fill your cart, then decide which day and timeframe you'd like your groceries delivered. One of our faves: Urban Roots Green Squash Veggie Noodles are great for whipping up low-carb "pasta" dishes.
I ate a lot of bacon, cheese, eggs and meat (steak and chicken mostly). For a person whose eating philosophy is typically more plant-based and whole-food-focused, eating processed pork products every morning took a lot of personal persuasion. It also took a complete mental shift, because eating multiple pieces of bacon every day for weeks on end goes against everything I've been taught for personal health.
×