The Ketogenic Diet: Fabulous or Fad?

By Stephen T. Sinatra, M.D., F.A.C.C., F.A.C.N., C.N.S., C.B.T.

If you haven’t heard about the ketogenic diet, you probably just got back from vacationing on Mars…

In all seriousness, though, “keto” dieting has taken the world by storm. Celebrities and fitness experts swear by its weight loss powers, athletes say it boosts their performance, and patients with Alzheimer’s, epilepsy, and other serious diseases have been able to use the ketogenic diet to treat, halt progression, or even reverse their conditions.

Even crazier, all of these claims about the ketogenic diet may actually be valid.

What Is the Keto Diet?

While it may seem like the latest weight loss fad, the ketogenic diet actually has a 100-year-long history.

In the 1920s, physicians used a ketogenic diet to treat epilepsy in children. Back then, researchers knew that extreme hunger (or even starvation) decreased the incidence of seizures. But instead of forcing kids to go hungry in an effort to treat their epilepsy, they created a diet to mimic the process that was reducing the seizures in the first place: ketosis.

During ketosis, the body uses fat for energy. It doesn’t normally, though. The body’s preferred fuel source is glucose, which is the easiest molecule for it to convert into energy. This glucose comes from dietary carbohydrates.

It’s an efficient system, especially for those who eat well-balanced diets with healthy ratios of fats, carbs, and proteins. But let’s get real for a second… Many (dare I say, most) people in this country follow the “standard American diet,” which as far too rich in refined carbs and sugars. Such high-carb diets lead to the overproduction of glucose. There are a few things that happen when too much glucose is coursing through the blood. The body uses whatever glucose it needs for energy. The remaining glucose then gets stored in the liver as glycogen. If there’s any that’s left after that, the body converts it and stores it as fat. (And you know what comes next: weight gain, then diabetes, heart disease, and other conditions related to obesity.)

With the ketogenic diet, you dramatically lower your intake of carbs and increase your intake of fats. As a result of this carb-limiting diet, the body no longer has the glucose it needs for energy. So it seeks out an alternative energy source—and that source is fat.

Fat starts to get broken down into ketone bodies (ketones for short), which generate energy and continue to do so until carbohydrates are reintroduced and glucose can once again be used. If that doesn’t happen, it will keep burning fat reserves indefinitely.

Benefits of the Ketogenic Diet

Research clearly shows that the ketogenic diet can be effective for weight loss and, as mentioned earlier, treatment of some types of seizures. But that’s not all. It shows promise with other neurological diseases like Alzheimer’s, as well as diabetes.

Weight loss is perhaps the main reason people want to give the ketogenic diet a try. And for many, it really works. The process of ketosis melts fat away as the body converts it to ketones, and noticeable results can often be seen within a week. The process of ketosis also happens to decrease appetite, which accelerates weight loss even more.

One study followed 83 obese patients who took part in a 24-week ketogenic diet. Not only did they lose weight, their LDL cholesterol and triglycerides significantly decreased, and their beneficial HDL cholesterol went up.

In a more recent study of 19,036 obese patients on a ketogenic diet, 15,444 experienced impressive weight loss (“a rapid 10% weight loss, 57% of which was fat mass”), with no major adverse effects. The researchers wrote that the diet is “safe, fast, inexpensive, and has good one-year results for weight maintenance.”

People who are overweight and have diabetes may also benefit from going keto. In a 24-week trial of 363 obese participants (102 of whom had type 2 diabetes), researchers wanted to see how a ketogenic diet compared to a low-calorie diet when it came to several measures, including weight, body mass index, waist circumference, blood glucose levels, hemoglobin, cholesterol, and triglycerides.

While both diets improved markers, the keto group saw far greater changes. The researchers concluded, “This study shows the beneficial effects of a ketogenic diet over the conventional low-calorie diet in obese diabetic subjects. The ketogenic diet appears to improve glycemic control…”

The keto diet also shows potential for slowing the progression of Alzheimer’s. For one, ketones appear to be neuroprotective, helping to prevent cognitive decline and degeneration in an aging brain. Among other benefits, ketosis can boost the activity of the antioxidant glutathione peroxidase in the hippocampus.

In an animal study, ketosis prevented amyloid beta plaques—a hallmark sign of Alzheimer’s. And in a trial of 152 people with mild to moderate Alzheimer’s, those who took an oral compound that induced ketosis showed substantial improvements on cognition tests by day 45, compared to the placebo group.

This research is still preliminary, but considering all the Alzheimer’s treatments available right now do little to stop disease progression, ketosis may provide the hope that these patients need.

Keto Diet Foods

A classic ketogenic diet involves completely eliminating all sugars (honey, maple syrup, agave, white/brown sugar, molasses, coconut sugar, etc.), all starchy veggies (tubers like white and sweet potatoes, and root vegetables such as beets, carrots, etc.), all grains and legumes, and most fruit. (It should also go without saying that all prepared and processed foods are no-nos.)

What’s left? Lots of fat, moderate protein, and a stingy amount of low-glycemic carbs. That translates to about 75% of calories from fats, 20% from proteins, and the remaining 5% or less from carbs. (Depending on body weight, this typically amounts to about 20–60 grams of carbs per day.)

Here’s a rundown of the allowable keto diet foods:

  • Meats: beef, lamb, pork, veal, venison, poultry, fowl, seafood, eggs
  • Leafy green vegetables: spinach, kale, collard greens, lettuce, endive, bok choy, arugula, etc.
  • Above-ground vegetables: cauliflower, broccoli, eggplant, cucumber, green beans, etc.
  • Coconuts, nuts and seeds, flours and oils made from nuts/seeds; nut butters
  • Avocados and low-glycemic berries (raspberries, blueberries, blackberries, etc.)
  • Healthy oils: olive, avocado, coconut, flaxseed, grapeseed, hempseed, and macadamia
  • Full-fat dairy: hard cheeses, Greek yogurt, and grass-fed butter
  • Full-fat, unsweetened dairy substitutes: coconut, almond, cashew, and soy milk
  • Low-carb sweeteners: stevia, monk fruit, erythritol

Drawbacks of the Ketogenic Diet

While I’m sure you’ll find many nutritionists and experts warning about dangers of the keto diet, I don’t really think there’s anything too harmful about it—as long as the fats you eat are primarily the healthy monounsaturated variety and you don’t go overboard on saturated fats. I would also make sure to eat only grass fed meat and dairy products, and free range or organic poultry and eggs to avoid GMOs and pesticides.

There are a few of the side effects to be aware of, though:

  • Frequent urination: The first few days of starting the ketogenic diet, as your body burns through all your stored glucose, you release a lot of water and excess sodium.
  • Hypoglycemia: Low blood sugar is common the first few days as well, especially for people who are used to eating a lot of carbohydrates. Dizziness, tiredness, shakiness, and hunger are symptoms of hypoglycemia, but they eventually subside once the body adjusts.
  • “Ketosis flu”: Many people experience flu-like symptoms the first three or four days of starting the keto diet. This also subsides.
  • Digestive issues: Constipation or diarrhea can occur due to the drastic change in macronutrient ratios. To make sure you’re getting enough fiber, eat lots of “allowable” vegetables and consider adding a fiber supplement like psyllium husk powder.
  • Bad breath: Acetone is one of the ketones created during ketosis. It definitely has a distinct odor that many find unpleasant, but it’s a good sign your body is in full-on fat-burning mode. Most keto dieters report their bad breath going away after a few weeks.

If there’s any concern I have about going keto, it’s this…

One of the most important characteristics of any diet or eating plan is not its ability to help you lose weight…because in reality, any diet promotes weight loss, especially in the short term. It’s the sustainability of the diet…meaning, is it a plan that you can easily follow for the rest of your life, and enjoy and thrive on? Does it provide all the nutrients you need to stay healthy? Does it help you not only maintain a decent weight, but also excellent heart health? While some research has shown that the keto diet is safe and sustainable, I’m not totally convinced.

Altering your macronutrient ratio so drastically is really hard to do…and it’s even more difficult to keep it up for months at a time. Can you imagine never ever having a strand of spaghetti, a banana, or a glass of wine again? If you’re a follower of strict keto diet, that’s your life.

This is why I’m such a proponent of the Pan-Asian Modified Mediterranean Diet (PAMM), which is a blend of the best of traditional Asian and Mediterranean dietary approaches.

The PAMM diet consists of a healthy, balanced ratio of fats, low-glycemic carbohydrates, and lean proteins—and it even allows for a glass of wine or occasional bowl of pasta, if desired. You never feel deprived, and for that reason alone, PAMM is extremely easy to follow indefinitely.

With that said, though, I don’t see any major reason to not give the ketogenic diet a try for a few weeks or months if you’re really struggling with your weight. (If you want to try it to help resolve or treat a serious health issue like epilepsy or Alzheimer’s, I highly recommend not going it alone and instead working with a doctor who’s knowledgeable in this area.)

My colleague and friend, Dr. Dan Pompa, is a strong believer in a “diet variation” strategy, where you adopt a keto diet for a few months, then add more starchy veggies and fruits back into the program (while continuing to avoid grains and refined sugars), then returning to keto. In his experience, the diet variations trigger metabolic shifts which result in weight loss.

And, if the very strict classic keto diet is too much for you, even a modified version—40% of calories from fat and 30% from both carbs and protein—has been shown to aid in weight loss. (Even better, a modified keto diet is a much more sustainable diet to follow long term.)

Finally, if you’re reading this and thinking, “Nope, Dr. Sinatra, the ketogenic diet is definitely not for me,” but you’re still curious about the potential benefits of ketosis, try intermittent fasting. As I mentioned earlier, “starving” for short periods of time puts the body into ketosis. With intermittent fasting, you’re not restricting any food groups; you’re simply eating in a short 8-hour window during the day (typically between noon and 8pm), and avoiding food the rest of the time. Lots of research praises intermittent fasting for weight loss and blood sugar control.

Whatever you choose to do, don’t lose sight of the big picture: Your health. If you look and feel absolutely fantastic on any particular diet, then it’s probably the right one for you. But if you look and/or feel sluggish, sick, and just plain terrible, then your body is telling you loud and clear that you aren’t giving it something it needs. It’s then time to reevaluate and try something new.


  • Wheless JW. History of the ketogenic diet. Epilepsia. 2008 Nov;49 Suppl 8:3-5. Last accessed June 19, 2018.
  • Dashti HM, et al. Long-term effects of a ketogenic diet in obese patients. Exp Clin Cardiol. 2004 Fall;9(3):200-205. Last accessed June 20, 2018.
  • Gianfranco C, et al. Ketogenic enteral nutrition as a treatment for obesity: short term and long term results from 19,000 patients. Nutr Metab (Lond). 2012;9:96. Last accessed June 21, 2018.
  • Hussain TA, et al. Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition. 2012 Oct,28(10):1016-21. Last accessed June 20, 2018.
  • Qin W, et al. Calorie restriction attenuates Alzheimer’s disease type brain amyloidosis in Squirrel monkeys (Saimiri sciureus). J Alzheimers Dis. 2006 Dec;10(4):417-22. Last accessed June 20, 2018.
  • Henderson ST, et al. Study of the ketogenic agent AC-1202 in mild to moderate Alzheimer’s disease: a randomized, double-blind, placebo controlled, multicenter trial. Nutr Metab (Lond). 2009 Aug 10;6:31. Last accessed June 20, 2018.

© 2018 HeartMD Institute. All rights reserved.

Leave a Reply


  1. Vivien

    on July 26, 2018 at 1:54 pm

    A Ketogenic diet seems to be recommended to starve cancer of sugar. What does anyone think of this?

  2. Richard

    on August 2, 2018 at 2:52 pm

    Not a good idea. Whatever your body uses as fuel likely could also be metabolized by the cancer. Personally, I believe that a ketogenic diet is an unnecessary extreme measure for weight loss or for treating cancer. If your diet includes a wide range of nutritious foods, I think you can enjoy anything you like and do not have to exclude anything. Of course, this presumes moderate portion sizes, exercise and a healthy lifestyle.

  3. Heather Carey

    on August 9, 2018 at 12:22 am

    Keto diet is extremely good for starving cancer – look at Complimentary oncologist Dr Lawenda – modified fasting diet. Also Dr Dom D’Agostino, who also adds in fasting and hyperbaric chamber oxygen. Hyperthermia is another way to stress cancer cells and not normal cells. Its not an extreme diet – once you work out what you can eat – avocados on a corn cracker for breakfast with coconut oil and MTC oil in the coffee, then add raw hemp seeds for protein and some organic wakame, green veggies in chicken or beef broth, add olive oil, tomato pasta sauce, erythritol/ stevia sweetener and sugar free chocolate or 75% – not too much, make your own yogurt with lactose free low fat milk/ with rhubarb /erythriltol/stevia/ cinnamon, then curry made with canned lentils ( eden brand) and coconut cream and permitted vegetables. Organic frozen berries are low sugar. Avoid non organic chicken,eggs and dairy fats ( naturally high in Oestrogen) . Tinned sardines or tinned tuna are OK. Go vegetarian if possible. Cancer also likes an amino acid higher in meat, chicken and fish. Add omegas 3 and CO Q10. Eat only organic chicken to make bone broths and lots of green veggies, olive oil, lemon juice, Avocado, Thats how I do it.

  4. Rich

    on December 17, 2018 at 4:46 pm

    I had lost weight in the past cutting carbs. I modified the past approach I had, with a list of Keto-friendly food, and also seek to avoid eating anything sweet. I am now eating more vegetables, using lower carb vegetables to replace grains I used to eat. I also do flax seed more. My weight is down from 275 to around 230 now, and I have more to go. I started late September 2018, to now middle of December. I am trying to balance more. I try to avoid sweets, but get a bit of a craving so I do a taste. Key part for me is to try to not only avoid sweets, but try to eat as much bitter and sour food, and thing that may be seen as “yucky” to adjust my taste preferences and acquire a taste for things better. Bitter taste apparently helps digestion, so that is a key part of what I am doing. I am not using any sticks or measuring any macros, just restricting things. Yuck thins the gut I will say.

  5. Tom Cadez

    on January 21, 2019 at 7:38 pm

    The name of your entity is – HeartMD Institute! I have read the article directly above, TWICE – and cannot find one mention of any heart related benefits relative to current heart patients. I have read of benefits for certain forms of cancer via glucose starvation along with certain Alzheimer and obesity disease studies backed by minimal research findings to support the benefits of ketosis but, that does not resonate to your company’s name, whatsoever. The issue here is that this misleading article makes severely diagnosed heart patients with significant heart issues (such as my Mother who is suffering from SEVERE CHF, COPD and severe breathing issues, ventricular tachycardia, renal failure, cardio edema and enema) think that the Keto Diet “Fad” is OK for them to try, as she is currently doing. The proneness to ketosis in CHF suggests increased use of fatty acids as an energy source. Considering the low cardiac output of severe CHF, this is uneconomic because more oxygen is needed with fatty acid than with glucose oxidation to produce the same amount of energy. Measuring the degree of ketonaemia has direct clinical utility in CHF. Proneness to ketosis provides an additional index of the severity of CHF and could also be taken as a warning of incipient malnutrition. The “Heart Institute” should not, in any ethical or other manner, recommend or make heart patient believe that the Keto diet is good for heart patients. This becomes especially troubling considering the facts that you have no substantial research from patient studies which currently, have not been conducted by any keto-based institution. Almost all cardiologists recommend cardiac-recommended diets to their current heart patients, for good reason. It is obvious that you have no substantiated research to substantiate alternative recommendations to severe heart patients. Your research footnotes above do not include one study that is relative to current heart patients yet, it is perceived from your article that these critical patients could benefit from such a diet plan, which is completely false. I am the CEO of a media company and conduct research for a living, quantifiable research! I know the differences between substantiated and unsubstantiated claims and what products or fake news falls under each category … Please discontinue to mislead current heart patients into thinking that ketosis is of benefit to them – it is not! If you feel that I am off-base with my comments and concerns, please provide to me just one research paper that suggests that severely hampered heart patients should replace their cardiologist recommended dietary plan with the Keto Diet. Thanks in advance for your reply to my post … Sincerely, Tom Cadez, CEO – Spectrum Media/CMI

  6. HeartMD Editor

    on January 30, 2019 at 4:57 pm

    Hi Tom, HeartMD Institute is Dr. Sinatra’s informational website, through which he discusses heart-healthy living practices. It is intended for the general public – healthy people and heart patients alike. This article is a brief exploration of the pros and cons of the keto diet, not a prescription for heart patients. And if you read through it, you’ll see that Dr. Sinatra recommends another diet – the PAMM diet – because he feels that keto is not sustainable for most people. Please download a free copy of Dr. Sinatra’s PAMM diet ebook to learn more Best of luck to you and your mom.

  7. June Granger

    on January 31, 2019 at 10:29 am

    I will try it. I’m sure it will be beneficial to my health

  8. David Kipping

    on February 3, 2019 at 7:22 am

    BS radar: “…never ever having a strand of spaghetti, …or a glass of wine again? If you’re a follower of strict keto diet, that’s your life.”
    That’s sooo untrue. Dry white and red wine have around 2 grams per serving (some are even lower). So you can have 1 or 2 every day with hardly any influence on your ketosis. A typical beer has 13 grams so 1 glass every now and then might still be possible depending on how low you need to stay -below 20 gr or 50 gr?
    And ofcourse, strands of anything are always possible. And anyway, even if you overdo it and get out of ketosis every once in a while. So what!? As long as you’re in ketosis for the large majority of time, you’re still that much better than the average Joe.

  9. Michael Siddle

    on March 8, 2019 at 12:16 am

    Anyone criticising the keto diet has tried it seriously. I have been on it for years, lost a stack of weight and improved my health dramatically. You lose any desire for carbs when you become fat adapted, You very rarely get hungry and the range of substitutes is endless. In fact the vast majority of carb based foods can be substituted. Most fruits , potatoes and rice are out but can be substituted. Eg blueberries and strawberries are fine, we eat ice cream made with cream and erythritol and non sugar based flavors, cheesecakes made with cream cheese and diet jelly, we have bacon and eggs, and cheese omelettes, steak, chicken, fish, prawns and oysters, smoked salmon and salmon cutlets. We have pizza where the base is made from almond flour, eggs, mozzarella cheese and cream cheese, which is much nicer than wheat flour pizza. We have lasagne using the same mix as the pizza base for the pasta substitute, delicious, we have cakes and coconut ice and chocolate, all sugar free! We have bread made from almond flour, flaxseed, psyllium husk and coconut flour. We have curries with cauliflower rice and nan made from coconut flour and we have pancakes with sugar free maple syrup, blueberry syrup, strawberry syrup or chocolate syrup all carb free or very low carb – yeh, sure it is a really hard diet to stick with because you can’t eat a strand of spaghetti! LOL. Get real!

  10. Alberto Carrilho

    on April 9, 2019 at 8:51 am

    I think the statement “the body’s preferred fuel source is glucose” is grossly inaccurate. I’m not going to swear by this (please look into it), but I’m given to understand ketones are a more efficient fuel source, and cells will prefer ketones over glucose in the presence of both. Glucose may be a “faster” fuel, but that doesn’t make it better or ideal for the human body. I think this distinction is very importat.

  11. Judith Cervizzi

    on April 24, 2019 at 7:55 am

    Love all the comments. Here is my thought: Not every diet is appropriate or effective for the vast populace. Listen to your body. I could not successfully do Keto because of severe hypoglycemia diagnosed by the late Dr. Robert Atkins. Keto lowers your blood sugar. In my case, it got lower which made me sick. I don’t have weight to lose. I wanted to follow keto for lowering cholesterol and preventing Diabetes. Any thoughts?

  12. Dorothy moton

    on April 24, 2019 at 11:56 am

    I would like to know does the Keto diet with so much fat clogg your arteries.

  13. Todd Cory

    on July 14, 2019 at 8:05 pm

    “I don’t have weight to lose. I wanted to follow keto for lowering cholesterol and preventing Diabetes. Any thoughts?”

    try a low glycemic, plant based diet. works exceptionally well for me.

  14. Nick

    on August 15, 2019 at 12:06 am

    I’ve had CAD since ’03 as far as I know. A bad case of angina then put me in the ER and it was found I had 2 blocked arteries, one received 2 stents, the other was left blocked as it was explained that I was growing collaterals to shunt the blood. I was an avid hiker before this event as I still am. I still had chest pain for 10 years following the stents if starting to do a hike too fast or with heavy exertion. My Docs PA alerted me 6 years ago that my fasting blood glucose looked like it may be in the prediabetic range. This freaked me out so I starting researching it and found out about dietary ketosis and how this could reverse it. I immediately started dropping my carb heavy eating habits and got into ketosis. That was late in 2013. I still eat keto and the most amazing thing is within my first couple of months of the keto diet all my chest pains subsided and have not returned. My cardiologist says it’s because my collaterials opened up, I say it’s the ketogenic way of eating. Whatever the reason, keto works, my doc say’s my labs and stress tests prove whatever I’m doing is working and working very well.

  15. Claire

    on March 2, 2020 at 9:47 am

    I want to do intermittent fasting but I’m very confused about my heart medications. I can’t seem to find a definitive answer regarding the proper time to take them while fasting. My question…
    Will taking them during a 18-20 hour fasting window disrupt the fast? I’ve reviewed each med and the only one that says it should be taken with food is not for absorption but to decrease the likelihood of GI distress.

  16. Janel

    on March 2, 2020 at 12:22 pm

    I tried the keto diet last year starting in mid May. Within 2 weeks I developed Atrial fibrillation very badly which I had never had before. Keto affects your eletrolyte balance and that is how it started for me. Now I have to take extra high blood pressure meds and Eliquis 2x a day. There are other heart health journals and web sites that state clearly that Keto diets are not good if you have heart issues, especially the possiblility of A-fib.

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