The ketogenic diet, often shortened to "keto," has gained significant popularity as a weight-loss strategy and potential therapeutic approach for various health conditions. This article delves into the intricacies of the keto diet, exploring its mechanisms, potential benefits, drawbacks, and practical guidelines.
What is the Keto Diet?
The keto diet, also known as the ketogenic diet, is a low-carb, high-fat, and moderate-protein diet. Unlike many other diets that are hard to uphold socially, keto also allows for moderate consumption of wine and other alcohol.
How Does Keto Work?
The ketogenic (keto) diet works by starving the body of carbohydrates. When only fat is available, your liver uses fat as an alternative fuel and turns fatty acids into ketones. From your brain to your blood cells, glucose is typically the most readily available source of energy. We get glucose from the foods that we eat - whether that’s breads and refined sugars or those found naturally in nature, like fructose from fruits. But to keep the body and brain functioning in times of starvation when carbohydrates weren’t available, the human body can adapt to using ketones, instead of carbs for fuel.
Ketogenesis has existed as long as humans have. If you eat a very low amount of carbohydrates, you starve your brain of glucose, the organ's main fuel source. Your body still needs fuel to function, so your brain flips the switch to tap into your reserve of ketones, which are compounds the liver creates from fat when blood insulin is low. This process is known as ketosis: It’s like when a hybrid car runs out of gas and reverts to pure electricity. There's nothing inherently magical about ketones. In fact, you already have them in your body. “Your liver produces ketones all the time, but the rate depends on carbohydrate and protein intake,” says Jeff Volek, Ph.D., R.D., a professor of human sciences at Ohio State University. When the majority of your diet is made up of carbs and protein-as the average American diet is-ketogenesis (the process of producing ketones) slows. Replacing carbs and protein with fat will put your body into ketosis, thus ramping up ketone production. Essentially, you'll burn fat instead of carbs for energy. Ketosis is not instantaneous, and the process takes about three days to induce-often with some side effects during the transitioning stages.
Does the Ketogenic Diet Work?
According to the NIH, there is, “no doubt that there is strong supportive evidence that the use of ketogenic diets in weight loss therapy is effective.” In fact they agree that there are many other positive benefits too, like improved mood and protection from cognitive impairment caused by obesity. For some, the keto diet can be easier to maintain than other diets because you get to eat delicious foods like nuts, avocados, and cheese, while still feeling full.
Read also: Easy Low-Carb Cheese Crackers
When it comes to weight loss, "there is no question that ketosis does work in the short term," Konstantinos Spaniolas, M.D., associate director of the Stony Brook Metabolic and Bariatric Weight Loss Center in New York. It makes sense in theory, and the keto diet entices people by allowing those who participate many cult-favorite foods. Come on, a diet where you can eat endless amounts of bacon and Gouda? We're sold (maybe).
However, the rapid weight loss which occurs at the start of a keto diet may not be fat loss at all. “Early weight loss at the beginning of the Keto diet is likely related to fluctuations in fluid,” says Ashley Harpst, R.D., a sports dietitian and the owner of Go For the Gold Nutrition in San Diego. “Three to four ounces of water is retained for every 1 gram of carbohydrate stored as glycogen in the muscles to use for energy.” So, as your glycogen stores are depleted and you enter ketosis, there’s less water in your body as well.
There's also no long-term data on ketogenic diets versus other diets. In a 2015 Italian study, those on a ketosis diet lost 26 pounds in three months. About half of the participants stayed on the diet for a year but lost little additional weight in the next nine months. People in a 2014 Spanish study who followed a very-low-calorie ketogenic diet lost an average of 44 pounds in a year-but a third of them dropped out, possibly because it was too hard to maintain.
Another study, published in 2020 in The BMJ, analyzed the results from 121 previously conducted clinical trials that looked at the effectiveness of various diets (low-fat, low-carb, low-calorie, etc.) for weight loss and lowering markers of cardiovascular disease risk, like blood pressure and LDL cholesterol. Based on data from nearly 22,000 adults, the researchers found that while all of these diets led to weight loss and improvements in cardiovascular health markers in the first six months, virtually all of those benefits had disappeared at the one year mark.
The bottom line: Keto (and any other diet) may lead to weight loss and improved health in the first several months, but even if you’re able to stay on the diet for longer, those benefits will likely disappear after about a year.
Read also: Keto Calorie Counting: A Detailed Guide
What Do You Eat on the Keto Diet?
With keto you should aim to have 70% of your calories come from fats, 25% from protein and 5% or less from carbs. With keto you should get the majority of your calories from fat and some protein. This means eating high-fat proteins and choosing low-carb vegetables like cauliflower. Remember- carbohydrates should make up less than 5% of your entire calorie intake. Aim to have an absolute maximum of 50 grams of net carbs a day, but aim for 20 grams or less. Someone following a keto diet should try to have a maximum of 50 net carbs every day.
A ketogenic diet generally requires that fat comprise 60 to 80 percent of your total calories. Protein take up about 20 percent, while the remaining 10 percent comes from carbs. Proponents of a ketogenic diet often recommend limiting your carb intake between 20 to 30 grams per day in order to maintain ketosis.
Foods to Eat on Keto
- Fats: Olive oil, avocados, nuts, eggs, butter, coconut oil
- Proteins: Chicken, tofu, turkey, beef, high-fat proteins
- Dairy: Cheeses - all kinds!
- Low-Carb Vegetables: Cauliflower, red bell pepper, kale, spinach, asparagus
- Fresh meat and fish: turkey, pork, chicken, lamb, beef, veal, venison, shellfish, tuna, cod, salmon, sardines
Foods to Avoid on Keto
- Sugary, starchy foods
- Grains: Rice, pasta, cereals, bread
- Starchy vegetables: Potatoes, corn, squash
- Most fruits
- Milk
- Beans and legumes
- Juices, sodas, and alcohol (can knock you out of ketosis)
- Bananas: While bananas are not an “unhealthy” food, their high carbohydrate count (28 net carbs for a small banana!) make them suboptimal for those on a keto diet.
Example Ketogenic Foods and Meals
- Breakfast: 4 eggs, 1/2 avocado, 1 to 2 Tbsp olive oil
- Lunch: 4 oz baked salmon with 1 Tbsp olive oil, 1/2 bunch asparagus with 1 to 2 Tbsp butter
- Dinner: Rib-eye steak, 2 cups spinach with coconut oil, 2 oz macadamia nuts
Are There Any Ketogenic Diet Side Effects?
Immediately after starting the diet during the first week, some dieters may experience what is referred to as the “keto flu“. But fear not! During the initial adjustment phase most dieters report rapid weight loss - losing up to 10 lbs of body weight in 2 weeks or less.
People who begin the diet often develop “Keto Flu,” as their bodies get accustomed to eating fewer carbs. During this time you may experience headaches, nausea, fogginess, muscle cramps and fatigue. Symptoms last about a week, but staying hydrated and getting ample sleep will help with cramps and exhaustion.
Aside from Keto Flu, you may notice a few other unpleasant side effects. Acetone-yes, the ingredient in nail polish remover-is one of the compounds found in ketones, so your breath may be stinkier than normal. Pooping may be difficult since cutting carbs will lower fiber intake, but a fiber supplement will help keep you regular.
Read also: Magnesium Supplements for Keto
There’s also the risk of nutrient deficiencies when you’re on the keto diet. “An individual who cuts out whole grains may become deficient in vitamin B1 (thiamine) and B3 (niacin),” Harpst says. These essential vitamins are added to grain products through fortification, as it’s tough to eat enough of them through food alone, and deficiencies can lead to adverse health effects. Iron and vitamin B9 (folate) are also added to grains, and while it’s relatively easy to get enough iron by eating animal products, eliminating grains can lead to folate deficiencies, as well. (This is particularly concerning for women who may become pregnant, as folate is essential for neural tube development in the first month of pregnancy, before most women even realize they’re expecting.)
And, while there’s not enough long-term research on keto diets specifically, a 2021 review published in Frontiers in Nutrition concluded that foods and nutrients typically consumed at higher than average levels on the keto diet (namely red meat, processed meat, and saturated fat) are linked to an increased risk of kidney disease, heart disease, cancer, diabetes and Alzheimers, whereas restricted foods like fruits, vegetables, legumes, and whole grains are associated with lowered risk of these same conditions. “Current evidence suggests that for most individuals, the risks of such diets outweigh the benefits,” the authors state.
Is Keto Like Other Low-Carb Diets?
Yes and no. While low-carb diets aren’t new, keto has a different macronutrient profile than other low-carb diets like Atkins. Most keto dieters start off with a diet where 70% or more of the calories come from fat- and carb intake is limited to just 5% of calories or less.
Keto vs.
Getting started with keto doesn’t have to be scary! Like with most diets, it can be easy to slip back in to old ways. To gauge how deep you are in ketosis, you can measure the amount of ketones your body is producing. Even if you think you’re sticking to your diet, sugar can hide in salad dressings, condiments, restaurant food and sauces, so it’s best to monitor how you’re doing every day.
Keyto - Ketone Breath Analyzer
The Keyto is a ketone breath analyzer. More than 10,000 Keytos have already been purchased.
Tips for Sticking to Keto
- Monitor Ketone Levels: To gauge how deep you are in ketosis, you can measure the amount of ketones your body is producing.
- Read Labels Carefully: Sugar can hide in salad dressings, condiments, restaurant food, and sauces, so it’s best to monitor how you’re doing every day.
- Gradual Changes: It can help to ease into the diet gradually. For instance, a person might stop eating one type of food at a time, such as bread or juice that is high in carbs and sugar.
- Whole, Unprocessed Foods: Aim to consume carbs from whole, unprocessed foods to benefit from their vitamins and minerals.
- Regular Health Monitoring: For people following the keto diet, regular health monitoring is important to check whether the diet is having any effects on the heart. For people with diabetes, it is also important to monitor for hypoglycemia (low blood sugar).
Can You Cheat on the Keto Diet?
Many people who are “keto-adapted” (have consistently maintained deep ketosis) report being able to stay in ketosis despite having a rare high-carb treat like beer, sushi or cake. But proceed with caution - “cheating” on a regular basis or designating a weekly cheat day is highly discouraged on keto. Due to the high fat concentration of keto foods you can easily regain the weight (or gain more weight) if you’re not actually in ketosis and cheating regularly.
Common Misconceptions About Keto
That’s a common misconception. But don’t just take our word for it. There is no literature or long-term evidence that implies keto is not a safe lifestyle or diet.
Is the Keto Diet Right for You?
This may sound like a cop out, but the best diet is the one you stick with. For Volek, who’s been following an ultra-low-carb diet for two decades, it works. If you can’t stick to it, then it probably won’t.
"This is the problem I have with all of these fad diets," registered dietitian Andy Yurechko, M.S., R.D., of Augusta University Medical Center in Georgia, previously told Men's Health. "A healthier type of diet is something you can do every day of your life."
Because maintaining ketosis requires strict carb counting, this diet works best for people who are diligent. And, it’s probably not a good idea for athletes or avid gym-goers to do the keto diet long-term. “There is no conclusive research to support any athletic performance benefit [of keto],” Harpst says.
Keto and Cancer Research: A Promising Avenue
Recent research has explored the potential of the keto diet in combination with cancer therapies. A study co-led by Liu and Guruprasad, with mentorship from Ruella and Levy, investigated the impact of various diets on CAR T cell therapy, a type of immunotherapy.
The research team tested the effect of several different diets, including ketogenic, high-fiber, high-fat, high-protein, high cholesterol, and a control diet, on CAR T cell’s tumor-fighting capabilities using a mouse model of diffuse-large B-cell lymphoma. They found improved tumor control and survival in the mice receiving a ketogenic diet compared to all other diets. According to Guruprasad, “Our theory is that CAR T cells prefer BHB as a fuel source rather than standard sugars in our body, such as glucose.”
Next, the research team tested a BHB supplement combined with CAR T cell therapy in laboratory models of human cancer (on a standard diet); the results showed complete obliteration of the cancer in the vast majority of mice and resulted in higher CAR T cell expansion and activation. To see if BHB, which occurs naturally at various level in our bodies, had a similar effect in humans, the team assessed blood samples from patients who had recently received CAR T cell therapy and found that greater BHB levels were associated with better CAR T cell expansion in patients.
Past studies across several cancer types have looked at the impact of dietary interventions, such as a high-fiber diet, on the response to cancer immunotherapy, however the mechanism behind the BHB effect in this study appears to stem from metabolic changes in the blood, rather than via the gut microbiome, as in the case of a high-fiber diet.
Levy noted, “We’re talking about an intervention that is relatively cheap and has low toxicity potential.” Ruella added, “As a physician and scientist, I share my patients’ excitement for potential new strategies to better treat their cancer, and I’m thrilled to see this research move from the lab bench to translational studies and now to a clinical trial.”