A Review of the Keto Diet

Dr. Christopher McGowan
febrero 27, 2023

People decide to lose weight for many reasons. For some, it’s about looking thinner or fitting some perceived societal standards of health and beauty. For others, it’s about becoming more healthy, or it may be a doctor-directed response to a serious illness. Whatever the motivation, the fact is that more Americans than ever are trying to lose weight even as rates of overweight and obesity continue to rise for both adults and children.

There are also almost as many ways to lose weight as there are reasons. Over the past few decades, more and more fad diets are becoming popularized on the internet and through social media. It can be hard to discern which ones have merit and which ones should be completely ignored. One diet that has remained popular is based on a low-carb concept that has roots that go back nearly a century: the keto diet.  

Origin of the Keto Diet  

The term “keto diet” is a modern shortening of ketogenic diet, a dietary therapy that was first developed in the 1920s. At the time, scientists were just discovering that fasting prompts the biochemical process called ketogenesis; this is when the liver converts fatty acids into ketone bodies that can be oxidized for energy. They soon also discovered that eating a very low-carb, high-fat diet produced the same basic result. In 1921, Dr. Russell Morse Wilder first coined the term “ketogenic diet” to describe a meal plan that would intentionally trigger ketogenesis in the liver.   

The original purpose of the diet was as a treatment for epilepsy, a neurological disorder in which misfiring neurons in the brain cause seizures. The idea of fasting as a treatment for epilepsy began in Classical Greece when Hippocrates proposed it as a cure based on empirical evidence of patients having fewer seizures when fasting. For over 2000 years, fasting was the default treatment for epilepsy; Wilder was simply proposing a new way to harness the benefits of ketogenesis without requiring a patient to go completely without food. 

While the ketogenic diet did show promising results for epileptic patients, it became clear that the treatment was much more effective in children. As a result, the diet stopped being used for adults. Throughout the 1930s and 40s, new anticonvulsant medications were developed that were a much more effective treatment. Over the years, the ketogenic diet as a treatment for epilepsy declined considerably; by the 1970s it was primarily only used to treat difficult cases such as patients with Lennox-Gastaut syndrome, a rare form of epilepsy that only affects children. 

The ketogenic diet was virtually unknown for many years until 1994 when the television show Dateline ran an episode that brought it back to light. The show told the story of a young boy with epilepsy who continued to experience seizures even with standard treatments. By adopting the ketogenic diet, the boy’s seizures were finally able to be controlled. While the diet referenced wasn’t new, it nevertheless sparked a resurgence in research about ketogenesis and the potential health benefits of a diet centered around the process.

By this point, the interest in ketogenesis for weight loss had already been established decades earlier with the 1972 book Dr. Atkins’ Diet Revolution, written by Dr. Robert Atkins. The so-called Atkins diet was also based on the idea of being in a state of ketosis (a state when the biochemical process of ketogenesis is active). Other variations, like the South Beach Diet, followed, but they were all based on the same principles. The “keto diet” as we know it today was simply a resurgence of the same ideas under a new name with a seemingly more legitimate pedigree.      

The Science of Ketogenesis           

The keto diet is based on the same concept of ketogenesis that was first described in the 1920s. The body has several pathways to meet the energy needs of cells. Carbohydrates from dietary sources are the primary way our cells meet these energy needs. When we don’t get enough through our diet, the body first turns to glycogen stored in the liver. When glycogen is depleted, the body uses gluconeogenesis to generate glucose from non-carbohydrate substances like lactic acid and certain amino acids. 

When glucose availability drops even further, as in prolonged periods of fasting, ketogenesis begins. During this state of ketosis, blood sugar is low as well as insulin secretion; this also means that both glucose and fat storage are effectively inhibited. Fatty acids are then converted into ketone bodies that become the body’s primary source of energy. The metabolism will remain in this state for as long as the body is deprived of carbohydrates. Research has shown that, in addition to body fat stores being reduced, ketosis is actually more efficient at producing energy than when the body is using glucose. 

How Does Ketogenesis Lead to Weight Loss? 

As noted, the benefits of the metabolic changes at the heart of the keto diet were intended to reduce the frequency of seizures in epileptic children. It remains unclear why exactly it has that effect, but it is more clear why it can lead to weight loss. By switching the metabolic pathway from glucose to ketone bodies, the body begins to regularly use fat stores for its energy needs. Over time, this means fat loss and therefore a lower body weight.  

The other aspect of a ketogenic diet that may contribute to weight loss is the changes it can promote in how many calories you eat and how hungry you are. In general, carbohydrates are less calorically dense and therefore tend to be less filling; by significantly reducing carb intake, it may reduce cravings that otherwise might lead to overeating. So in addition to burning fat stores, a keto diet may also help you reduce your overall calorie intake and thereby promote further weight loss. 

How Does the Keto Diet Work?

The ketogenic diet that was originally developed for children with epilepsy called for primarily fat with enough protein to support body growth and repair. This meant a 4:1 ratio of fat to combined protein and carbohydrates. To achieve this, you would have to exclude sugar, breads, whole grains, pasta, and starchy vegetables in favor of high-fat foods like eggs, butter, cream, nuts, and fatty meats. Even when it was initially used for epilepsy, it wasn’t considered a balanced diet, so vitamin and mineral supplements were needed to maintain proper nutrition. This is considered the “classic” ketogenic diet, but it isn’t used much anymore. Below are some other variants: 

  • Modified keto: The modified keto diet is very similar to the classic version, but it uses a 3:1 ratio of fats to combined protein and carbohydrates rather than 4:1. It still requires only 2-5% of energy to come from carbohydrates, but it shifts some of the energy that comes from fat to protein. 
  • MCT oil: This variant is based on the premise that the body is more efficient at metabolizing medium-chain triglycerides than the long-chain triglycerides found in butter and other animal fats that are typically found at the core of keto diets. The diet emphasizes palm oil and coconut oil in lieu of some of the other fats; it envisions that 40-50% of fat in the diet comes from MCT oil.  
  • Modified Atkins: The Atkins diet also relies on ketogenesis as the main mechanism of weight loss, but it has a unique program with different “phases.” The modified Atkins variant of the keto diet is based on the “Induction” phase of the Atkins diet and puts no restriction on the amount of protein that can be eaten. Carbohydrate intake is limited to 10 grams per day at first, and then it can increase after one or two months depending on the person’s tolerance for remaining in ketosis.   
  • Low glycemic index treatment (LGIT): This treatment is generally less restrictive and is based on the theory that maintaining a stable blood glucose level is the primary mechanism for the keto diet’s effectiveness. Like the other variants, it calls for a high-fat diet (60% of calories from fat), but it allows for 50-60 grams of carbohydrates per day from foods that have a glycemic index that is lower than 50.   

It’s important to note that these variants were all derived primarily as treatments for epilepsy rather than weight loss. Unlike Atkins or South Beach or many other low-carb diets, there isn’t an “official” keto diet that has a specific set of criteria. The potential weight loss from following a keto diet is essentially an unintended side effect, and there are now countless versions that can be found online that all draw from the same basic idea. Numerous authors, physicians, and nutritionists have given their own spin on an old concept. 

What Foods Do You Eat on a Keto Diet? 

Depending on what version of the keto diet you’re doing, you might have different proportions of carbohydrates, proteins, and fats. In general, though, the keto diet is more restrictive than other low-carbohydrate diets, so that means a lot of fat, some protein, and very few carbs. Below are some foods that are keto-friendly: 

  • Meat: beef, chicken, pork, turkey
  • Fish: salmon, tuna, sardines
  • Dairy: cheese, butter, cream, plain yogurt 
  • Fruits: berries, avocado
  • Non-starchy vegetables: broccoli, bell peppers, cauliflower, spinach 
  • Fats: olive oil, nuts
  • Eggs
  • Unsweetened coffee and tea 
foods to eat on a keto diet

Health Concerns with the Keto Diet

For as long as ketogenic diets have been used for weight loss, there have been questions about whether they’re actually a good idea. Most of the concern naturally stems from the singular emphasis on consuming mostly fat; this seems to fly in the face of decades of research and conventional wisdom about what constitutes a healthy diet. But the fact is that there are numerous health concerns that must be considered when evaluating this diet: 

  • Heart health: The fact that most versions of the keto diet require upwards of 80% of your total calorie intake to come from fat could be a major problem, depending on what kind of fats you’re consuming. A diet with a high amount of saturated fat, for instance, is considered a major risk factor for cardiovascular disease, high blood pressure, and even some types of cancer.   
  • Nutrient deficiency: The original formulation of the diet that was used for epilepsy treatment relied on dietary supplements since many of the foods that fit the keto diet don’t contain all of the vitamins and minerals the body needs. Without sufficient intake of fruits, veggies, and grains, a person could experience nutrient deficiencies that could lead to a variety of health problems.  
  • Liver health: A ketogenic diet by its nature forces the liver to process an abnormally high amount of fat. There is some evidence that the buildup of fat in the liver could lead to non-alcoholic fatty liver disease (NAFLD), a condition that can lead to long-term liver damage and eventual liver failure. 
  • Kidney health: For people who already have some form of kidney disease or kidney-related diseases like type 2 diabetes, high fat and high protein can put additional strain on the kidneys. There is even some evidence that it could lead to kidney stones or chronic kidney disease. 
  • Digestive health: Because of the need for such a low intake of carbohydrates, the keto diet tends to leave participants with insufficient amounts of dietary fiber. This can cause mild gastrointestinal symptoms like constipation and diarrhea, but it can also potentially negatively impact the balance and diversity of bacteria in the gut microbiome. 
health concerns with the keto diet

How Effective is Keto for Weight Loss?   

As with just about any diet out there, keto has many proponents who are quick to share anecdotal evidence about how much weight they were able to lose. The truth is, though, that research about the efficacy of any diet plan is generally sparse because of how difficult it is to collect data on what people eat every single day over a long period of time. It is especially difficult to determine the effectiveness of keto diets because there are many different types advocated by many different people. 

There have been, however, a few studies done in recent years that show that ketogenic diets are able to promote more weight loss over the short term than some other diets. A 2013 meta-analysis of randomized controlled trials, for instance, found that participants on a low-carb ketogenic diet lost about two pounds more than those who were on a low-fat diet after one year. More research is needed, however, to determine if such losses could be sustained over the long term and whether or not the diet can lead to long-term health problems.   

What Do the Experts Say? 

Weight loss is a complex subject, and there are always new studies that can be difficult to interpret. Sometimes you just need to turn to an expert for the best advice. Laura Sebring, MS, RD, LDN is a Registered Dietitian at True You Weight Loss, and she has answers for some of the most common questions about keto:  

What are the pros and cons of keto?

  • Pro: The pros of a ketogenic diet are that most people can lose weight on it, as long as you have a caloric deficit. It has also been shown to benefit those with epilepsy. 
  • Con: Cons are that it is very difficult to adhere to this diet and sustain it for a long time. Once someone comes off the diet, the weight generally returns quite quickly.
  • Con: Anyone with cardiovascular disease, pancreatitis, high cholesterol (especially triglycerides), or bariatric surgery should avoid a ketogenic diet. Those who do not have a gallbladder may also have trouble with gastrointestinal issues on this diet.
  • Con: Low carbohydrate diets can lead to fatigue, headaches, and brain fogginess.
  • Con: This diet can also contribute to gout due to increased levels of uric acid in the blood. 

What have you found people are generally unaware of when considering keto? 

  • People are unaware of the exact levels of carbohydrates and fat required to remain in ketosis. Most people who claim to be on a ketogenic diet are not truly in ketosis.
  • A lot of people do not realize that some fats can be very unhealthy and eat meals that look something like a cheeseburger without the bun and a heaping side of bacon.
  • Anyone attempting to lose weight on a ketogenic diet should be closely monitored by a dietitian and have regular lab work performed by their healthcare provider. 

Do you have firsthand experience with keto, whether it's something that you've personally tried, or have seen others be successful or unsuccessful with? 

  • I have never tried a ketogenic diet myself. I have had many patients who have tried it before coming to me for weight management counseling. I would estimate that 50% of them were successful at losing weight on the diet, but obviously, if they came to me, they regained the weight. Many mention that it was too difficult to follow long term or that their lab values changed in a negative way.
  • My personal experience regards a friend who reached out to me about a ketogenic diet after suffering a severe pancreatitis attack that landed her in the ER. She had a roux-n-y gastric bypass many years ago. These patients have a malabsorptive component to their procedure because the small intestine is rerouted. Fat is absorbed in the small intestine. The pancreas creates enzymes that break down fats. When you eat a high fat diet, such as the ketogenic diet, your triglyceride levels can increase, and your pancreas can become overtaxed. Thus, those with malabsorptive bariatric surgeries such as roux-n-y gastric bypass or duodenal switch, should avoid eating a ketogenic diet.

For someone that might be considering keto, what alternative options should they consider and why?

  • I do not usually recommend following a “diet” but more of an “eating pattern.”  Your daily intake should consist of lean protein sources, whole grains, and plenty of fruits and vegetables. You should be mindful of sodium intake as well, generally aiming for 2300 mg per day or less. 
  • Some healthy “eating patterns” to consider are a Mediterranean style of eating or DASH (Dietary Approaches to Stop Hypertension). A Mediterranean style consists of a high intake of fruits, vegetables, whole grains, fish, and healthy fats and oils. DASH promotes heart health and tends to focus on increased lean meats and fish, fruits and vegetables, fiber, low fat dairy, low in refined sugar, and low in sodium.

Bottom Line 

The principles behind the keto diet and the metabolic effects of restricting carbohydrate intake have been apparent for a long time, and the emphasis on finding a better balance of macronutrients has merit—especially given that the average American diet has far more refined carbohydrates than are recommended for good health. There is also some evidence that a keto diet can lead to weight loss, at least over the short term, but it’s worth reiterating that the diet was never intended as a means of weight loss.  

One aspect of ketogenic diets (including Atkins and South Beach) that isn’t necessarily reflected in the data is that the incredibly restrictive diet makes them difficult to stick with over the long term. Withholding so many categories of food can be emotionally difficult and socially isolating. Many people cave in and eat that donut someone brought to the office or the piece of cake at a friend’s birthday party. That can leave someone feeling defeated and dejected and can lead to overeating when they return to their old ways. 

The bottom line is that a ketogenic diet can potentially be a pathway to weight loss for some people. In many ways, though, it requires a much bigger and more intense commitment than a lot of other diet plans. And the research currently available seems to indicate that it isn’t significantly more effective at promoting weight loss than other methods. There are also long-term health concerns with the kinds of foods that might end up being at the center of such a diet plan. 

Other Ways to Lose Weight 

Though the keto diet is based on some long-accepted principles of metabolism and how ketogenesis is triggered, in practical terms it’s a fad diet like most other diet plans that you can find on the internet. Weight loss is hard, and there are no magic diets that can bring rapid weight loss that is also sustainable over the long haul. In fact, most people who go on diets and manage to lose a little weight end up gaining it back after a year or so. 

If you’ve tried a bunch of different diets and haven’t found the freedom you’ve been looking for, you’re not alone. At True You Weight Loss, we are passionate about helping people find a new, sustainable approach to weight loss. We offer non-surgical weight loss solutions like gastric balloons and ESG that can help you finally turn the corner and never look back. To learn more about True You and how we can help, please contact us to solicitar una consulta.  

Dr. Christopher McGowan
Dr. Christopher McGowan
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