In essence, it is a diet that causes the body to release ketones into the bloodstream. Most cells prefer to use blood sugar, which comes from carbohydrates, as the body’s main source of energy. In the absence of circulating blood sugar from food, we start breaking down stored fat into molecules called ketone bodies (the process is called ketosis). Once you reach ketosis, most cells will use ketone bodies to generate energy until we start eating carbohydrates again. The shift, from using circulating glucose to breaking down stored fat as a source of energy, usually happens over two to four days of eating fewer than 20 to 50 grams of carbohydrates per day. Keep in mind that this is a highly individualized process, and some people need a more restricted diet to start producing enough ketones.
A ketogenic diet may be an option for some people who have had difficulty losing weight with other methods.  The exact ratio of fat, carbohydrate, and protein that is needed to achieve health benefits will vary among individuals due to their genetic makeup and body composition. Therefore, if one chooses to start a ketogenic diet, it is recommended to consult with one’s physician and a dietitian to closely monitor any biochemical changes after starting the regimen, and to create a meal plan that is tailored to one’s existing health conditions and to prevent nutritional deficiencies or other health complications. A dietitian may also provide guidance on reintroducing carbohydrates once weight loss is achieved.
More Sustained Energy: 90-120 minutes after you eat carbohydrates, your body doesn’t have readily available energy produced from the mitochondria in your cells, so you start “crashing” or lowering your energy. When you are in ketosis, your body can run off your body fat, which is an essentially limitless source of fuel. This prevents any type of crash.

Carrie, I highly recommend a support group. I personally know a woman “Amanda Rose” who recently lost half her body weight through the Keto Diet and intermittent fasting. You should totally join her Facebook Group. It’s called “Eat Like a Bear” and you can find it by entering the group’s name in the Facebook search bar. She is so amazing and so supportive for people struggling to lose the weight.


Positive science on ketosis coupled with personal successes passed by word-of-mouth have driven more people to explore the ketogenic diet, says Volek. More recently, the keto diet hints at having a promising therapeutic role in cancer, Alzheimer’s, Parkinson’s and polycystic ovary syndrome (PCOS). Research is still early in many areas, but Volek suspects there will more definitive answers on the wider scope of the diet’s benefits within the next decade.
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).
“I discuss nutrition with all my patients as I believe lifestyle choices have an important impact on both physical and mental health. I recommend a simple whole-foods, low-carbohydrate diet, intermittent fasting or both, to many of my patients. I use the Diet Doctor website myself as I enjoy the ad-free, simple, but very comprehensive approach to low-carb eating and I recommend it to my patients as well as to my colleagues, friends and family.”

“I have been staying informed about therapeutic nutrition, diabetes reversal, and the role of diet in optimal metabolic health, and I am also practicing a low-carbohydrate diet. I do not believe in a one-size-fits-all approach to diet; what works for one person may not work for another. As a physician, I am very interested in the possibilities that good nutrition can bring to lifelong health.”
Overall this seems to be a very good diet for most people as far as fat loss is concerned. Some do deal with negative side effects while in ketosis but most people will find that although it's really hard the first two weeks, after that period their body begins to adapt and it gets much easier. Furthermore, one of the biggest benefits of being in ketosis is appetite blunting therefore it can actually be an ideal program for someone on a diet.
Gut health is extremely important for anyone looking to lose weight and increase overall health[*][*]. It is not uncommon for those who shift to a ketogenic diet to have a change in the production of bacteria in their colon (although not necessarily a bad thing – just a change)[*]. To help support this change and increase the healthy bacteria in your gut, try consuming more fermented foods such as sauerkraut, kimchi or kefir and/or supplement with a high-quality probiotic[*][*].
During the ketosis phase of the nutritional intervention, the IWQOL-Lite scores did not change for the sexual life, social anxiety, and work area domains (Table S1). A significant improvement was observed in the physical function and self-esteem scores during this phase. When comparing the visit of reduced ketosis and endpoint with baseline, a significant improvement was found in all domains, except for social anxiety, which did not change throughout the nutritional intervention.
There is a lack of evidence of the usefulness of low-carbohydrate dieting for people with type 1 diabetes.[1] Although for certain individuals it may be feasible to follow a low-carbohydrate regime combined with carefully-managed insulin dosing, this is hard to maintain and there are concerns about potential adverse health effects caused by the diet.[1] In general people with type 1 diabetes are advised to follow an individualized eating plan rather than a pre-decided one.[1]
Yes, you'll lose weight but only because you're consuming fewer calories. There's no real magic to the keto diet. The weight-loss equation remains the same: You lose weight when you consume fewer calories than you use each day. You're not burning more fat than other diets, or at a faster rate. On the keto diet, you eat high-fat meals with protein, which keeps you feeling full for longer and cuts down on your overall eating throughout the day.
Remember, the point of the ketogenic diet is to enter ketosis by limiting your carbohydrate intake to about 5% of your total calorie needs and consuming about 75% of your calories in the form of fats. Vegetables and fruits naturally contain carbohydrates, and the ones included in the list above are lower in carbohydrates while not skimping on nutrients.
At this point, we don’t know how long is safe to remain in ketosis. Based on the clinical trials, I recommend a trial of ketosis for up to 6 months, under the care of a knowledgeable functional medicine physician. There are some clinical trials up to 12 months, so that would be the maximum I would recommend under the watchful eyes of a collaborative professional and expert.
Hey Patricia, you definitely want to fill up on fat and make that the majority of your calories. Fat is very satiating so you will probably get fuller, faster compared to when you would eat carbs. However, if you are eating an excessive amount of fat (past your satiety level) than it has to go somewhere and anything in extreme excess will be most likely be stored in your body as body fat. I recommend eating to satiety and if you are not seeing results, you may have to track your consumption for a few weeks so you have a better idea of how much you’re consuming and what works best for your goals. Our macro calculator can help get you started with that if you’d like: https://perfectketo.com/keto-macro-calculator/
If you need to eat more or fewer calories per day, you can adjust accordingly by simply taking out or adding a bit more of the ingredients already included in a recipe. For example, adding/removing a tablespoon of olive oil or butter will add/remove about 100 calories. If you like or dislike certain recipes, feel free to shift things around. Make sure to keep an eye on the calories so you’re still falling within an acceptable range of your daily goal.
I have great respect for Harvard Medical School. I notice that they support their readers posting comments and I am most appreciative of the article and all the many thoughtful comments by the readers. The readers seem to have the most expertise here and I hope that the doctor who wrote the article will think long and hard about the comments by readers. After 35 years of clinical practice in mental health, I notice that all issues of emotion involve medical issues, nutrition, and the gut bacteria. I would say that these issues and all of the executive brain functions seem to improve with ketogenic principles. For those that apply it in a flexible and smart manner, it appears to improve every area of their lives. I strongly encourage the author of the article to take one class via The Institute for Functional Medicine. If he is open to more learning he can take more classes and get certified. I’m sure a fine doctor, he will be an even better doctor and personally healthier, if he gets more training. Are we all open to new learning(especially us healthcare providers)?
“The totality of evidence is very clear: A low-carbohydrate dietary approach is the most effective way to manage the insulin resistance syndrome which is that single biggest driver of obesity, type 2 diabetes and cardiovascular disease. Diet Doctor has been instrumental in providing extremely useful, clear and educational material to all who want to implement this dietary approach in to their lives. That’s why I recommend the website to all my at-risk patients.”
Researchers believe that the ketogenic diet can also help patients with schizophrenia to normalize the pathophysiological processes that are causing symptoms like delusions, hallucinations, lack of restraint and unpredictable behavior. One study found that the keto diet lead to elevated concentrations of kynurenic acid (KYNA) in the hippocampus and striatum, which promotes neuroactive activity. Some studies even point to the elimination of gluten as a possible reason for improved symptoms, as researchers observed that patients with schizophrenia tended to eat more carbohydrates immediately before a psychotic episode. (19)
61. Thomson C.A., Morrow K.L., Flatt S.W., Wertheim B.C., Perfect M.M., Ravia J.J., Sherwood N.E., Karanja N., Rock C.L. Relationship between sleep quality and quantity and weight loss in women participating in a weight-loss intervention trial. Obesity. 2012;20:1419–1425. doi: 10.1038/oby.2012.62. [PMC free article] [PubMed] [CrossRef] [Google Scholar]
I did Atkins way back and successfully lost 40 lbs and also my gallbladder. Today, I love being in ketosis. (Down 35 lbs so far). There is a learning curve, for sure, and yes, I “fell off the wagon” for a time (long enough to gain a couple pounds back and feel hungry all the time and lethargic) but I am now back in ketosis & love the mental clarity, the energy, weightloss & best of all, not being hungry all the time!
Keto friendly foods are quite high calorie. Fat has 9 calories per gram compared to the 4 for protein and carbs. And during the first week or so you may end up not maintaining much of a deficit because of how much you're used to eating. But as you get used to it, you'll find you don't need to eat as much to feel satisfied. So yeah, bacon has a lot of calories, but 4 strips will leave you feeling satiated with no need for toast or pancakes with it.

By design, the nutritional intervention induced an important reduction in BMI and fat mass, especially visceral fat mass through the study visits synchronized with the ketone levels in four visits (Figure 1). Thus, at the end of the nutritional intervention, the patients were out of ketosis (0.2 ± 0.1 mmol/L) with a total of 7.7 units of BMI lost (Figure 1). Most of the initial body composition loss was in the form of total fat mass (Figure 1). Relevantly, from the total fat mass, visceral fat mass, the most physiological and clinically relevant fat depot, was significantly reduced after the VLCK diet (−1.2 ± 0.7 kg; p < 0.05).
“I really believe that the more informed you are about the benefits of a healthy bite versus the chain reaction that you’re going to put into effect in your body when you take that bite — you just suddenly don’t want to make that choice for yourself anymore. It’s beyond willpower at that point; it’s become a desire to do something good for yourself.” — Christie Brinkley
Combine that with the fact that your body is excreting more water, and you have a potential recipe for clogged pipes. You can keep things moving by getting some fiber from keto-friendly foods like avocado, nuts, and limited portions of non-starchy vegetables and berries, says David Nico, PhD, author of Diet Diagnosis. Upping your water intake helps, too.
Although the patients underwent a total of 10 visits, the complete body composition analyses were synchronized with the ketone levels in 4 visits (Table 1; Fig. 1). Visit C-1 was the baseline visit, before starting the diet, with no ketosis (0.0 ± 0.1 mmol/L) and a body weight of 95.9 ± 16.3 kg. Visit C-2 was at the time of maximum level of ketosis (1.0 ± 0.6 mmol/L) with a body weight of 84.2 ± 18.0 kg. At visit C-3 (after 89.7 ± 19.1 days of VLCK), patients began the return to a normal diet and showed a reduction in ketone levels (0.7 ± 0.5 mmol/L) and a body weight of 76.6 ± 11.1 kg. Finally, at visit C-4, the patients were out of ketosis (0.2 ± 0.1 mmol/L) and showed a body weight of 75.1 ± 11.8 kg. All weights were statistically different from baseline levels (P < 0.05; Table 1; Fig. 1).
Check nutritionally-complete low-carb menus with under 50 grams of net carbohydrate per day to see what a ketogenic diet could look like. These menus are, however, going to be too high in protein for some people to remain in ketosis, and some of them may be a little high in carb if you have very poor carb tolerance. Keep in mind that ketogenic diets should always be tailored to the individual.
Twenty obese patients followed a VLCK diet for 4 months. Body composition assessment was performed by dual-energy X-ray absorptiometry (DXA), multifrequency bioelectrical impedance (MF-BIA), and air displacement plethysmography (ADP) techniques. Muscular strength was also assessed. Measurements were performed at 4 points matched with the ketotic phases (basal, maximum ketosis, ketosis declining, and out of ketosis).
It’s also currently as trendy to the fitness world as kale and açaí are to the pseudo-hipsters who wear beanies, even in the dead-heat of summer. If you haven’t tried keto on for size, maybe give it a go (unless you’re a complete and utter carb bitch, and cramming yourself full of bagels and pancakes just makes your abs really pop - in which case, the rest of us hate you on the inside. Just a little.)
Well, I am going to give this another try. I have great difficulty in eating greens , or drinking them, also I am not fond of fats, years and years of low fat diets have totally screwed my metabolism,and taste buds. I will read this page every day to keep my mind focused. Start tomorrow when I get up …… I work nights which can cause me problems as well. When I tried this diet before, I got terrible cramp, now I realise I wasn’t drinking enough water. Anyway.here goes.

Gluconeogenesis is the endogenous production of glucose in the body, especially in the liver primarily from lactic acid, glycerol, and the amino acids alanine and glutamine. When glucose availability drops further, the endogenous production of glucose is not able to keep up with the needs of the body and ketogenesis begins in order to provide an alternate source of energy in the form of ketone bodies. Ketone bodies replace glucose as a primary source of energy. During ketogenesis due to low blood glucose feedback, stimulus for insulin secretion is also low, which sharply reduces the stimulus for fat and glucose storage. Other hormonal changes may contribute to the increased breakdown of fats that result in fatty acids. Fatty acids are metabolized to acetoacetate which is later converted to beta-hydroxybutyrate and acetone. These are the basic ketone bodies that accumulate in the body as a ketogenic diet is sustained. This metabolic state is referred to as "nutritional ketosis." As long as the body is deprived of carbohydrates, metabolism remains in the ketotic state. The nutritional ketosis state is considered quite safe, as ketone bodies are produced in small concentrations without any alterations in blood pH. It greatly differs from ketoacidosis, a life-threatening condition where ketone bodies are produced in extremely larger concentrations, altering blood ph to acidotic a state.


A study of 89 obese adults who were placed on a two-phase diet regimen (6 months of a very-low-carbohydrate ketogenic diet and 6 months of a reintroduction phase on a normal calorie Mediterranean diet) showed a significant mean 10% weight loss with no weight regain at one year. The ketogenic diet provided about 980 calories with 12% carbohydrate, 36% protein, and 52% fat, while the Mediterranean diet provided about 1800 calories with 58% carbohydrate, 15% protein, and 27% fat. Eighty-eight percent of the participants were compliant with the entire regimen. [12] It is noted that the ketogenic diet used in this study was lower in fat and slightly higher in carbohydrate and protein than the average ketogenic diet that provides 70% or greater calories from fat and less than 20% protein.

Adequate food records were available for analysis in a proportion of participants at each of the 4 timepoints (Table ​(Table2).2). Participants completed food records at a mean of 2.5 and a median of 3 timepoints. In general, comparing baseline to subsequent timepoints, mean carbohydrate intake decreased substantially and energy intake decreased moderately while protein and fat intake remained fairly constant.
RESULTS: After VLCKD1 were reduced: Body Mass Index (BMI) (Δ%=-11.1%, p=0.00), Total Body Water (TBW) (p<0.05); Android Fat Percentage (AFP) (Δ%=-1.8%, p=0.02); Android Fat Mass (AFM) (Δ%=-12.7%, p=0.00); Gynoid Fat Mass (GFM) (Δ%=-6.3%, p=0.01); Intermuscular Adipose Tissue (IMAT) (Δ%= -11.1%, p=0.00); Homeostasis Model Assessment of Insulin Re-sistance (HOMA-IR) (Δ%=-62.1%, p=0.01). After VLCKD1 a significant increase of uricemia, cre-atinine and aspartate aminotransferase (AST) (respectively Δ%=35%, p=0.01; Δ%=5.9%, p=0.02; Δ%=25.5%, p=0.03). After VLCKD2 were reduced: BMI (Δ%=-11.2%, p=0.00); AFM (Δ%=-14.3%, p=0.00); GFM (Δ%=-6.3%, p=0.00); Appendicular Skeletal Muscle Mass Index (ASMMI) (Δ%=-17.5%, p=0.00); HOMA-IR (Δ%=-59,4%, p=0.02). After VLCKD2, uricemia (Δ%=63.1%, p=0.03), and Vitamin D levels (Δ%=25.7%, p=0.02) were increased. No significant changes of car-diovascular disease (CVD) indexes were observed after DTs. No significant changes of PPARγ lev-el in any DTs.
Total body composition was first measured by iDXA (GE Healthcare Lunar, Madison, WI). Daily quality control scans were acquired during the study period. No hardware or software changes were made during the course of the trial. Subjects were scanned using standard imaging and positioning protocols, while wearing only light clothing. For the current study, bone mineral density, lean body mass, and FM values, which are directly measured by the GE Lunar Body Composition Software (GE Healthcare), were used. Some derivative values, such as bone mineral content, regional lean mass, ALM, FFM, and FM percentage (FM%), as well as android and gynoid fat (%), were also calculated. The android/gynoid ratio was automatically generated and analyzed using enCORE software, version 13.6 (GE Healthcare). For measuring android fat, a region of interest was automatically defined as the caudal limit placed at the top of the iliac crest, and its high was set to 20% of the distance from the top of the iliac crest to the base of the skull to define the cephalic limit of abdominal subcutaneous adipose tissue. The scanner was calibrated daily against the calibration block supplied by the manufacturer.
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.
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