Author:Lisa Esposito Update:2024-11-27

The ketogenic (keto) diet involves significantly reducing carbohydrate intake and sometimes limiting protein while significantly increasing fat consumption. Although some keto dieters have experienced rapid weight loss, it is important to consider the safety and healthiness of this diet. Continue reading to learn about the potential for sustained weight loss and the safety of the keto diet.


What Is the Keto Diet?

Advocates of the ketogenic (keto) diet promote it as a high-fat, low-carb approach to weight loss that triggers the burning of fat. The diet's objective is to achieve rapid weight loss without experiencing hunger or cravings. In addition to weight loss, proponents of the keto diet suggest that it can enhance mood, sharpen mental focus, and raise energy levels.

What Is Ketosis?


By significantly reducing carbohydrate intake and increasing fat consumption, the body is forced to rely primarily on fat for energy. This metabolic state is known as ketosis, which is triggered by a perceived state of starvation. As a result of ketosis, the liver produces ketones, which are utilized by the body for energy when food is not available. Although the presence of ketones in the urine is a positive sign for individuals seeking to lose weight on the keto diet, it can be a sign of a health emergency for individuals with diabetes who are not following the diet.


Compared to other low-carb diets, the ketogenic (keto) diet is more stringent, typically limiting daily net carb intake to no more than 20 grams. Net carbs refer to the carbohydrates that the body digests and absorbs. To calculate net carbs, one subtracts the amount of fiber and sugar alcohols (found in sugar-free foods) from the total carbohydrates in a food item. For example, a single slice of bread can easily contain 20 net carbs or more.

How Does the Keto Diet Work?

Carbohydrates are the body's preferred source of energy. When carbs are consumed, the liver converts them into glucose to fuel the body. However, on the keto diet, you’ll be eating far fewer carbohydrates than you’re likely used to enjoying.

“When there isn’t enough (glucose), your body will start breaking down stored fat for energy instead,” says Lolita Carrico, a certified nutritionist based in Los Angeles. “This can cause you to lose weight over time as your body adapts to using ketones as its main source of fuel.”

As part of the keto eating regimen, the macronutrients are broken down into the following:

  • Fat: 70% to 80%.

  • Protein: 10% to 20%.

  • Carbohydrates: 5% to 10%.


During the first week, you may experience symptoms of carb withdrawal, including muscle aches, headaches, fatigue, mental fog and hunger. As the diet moves into the second and third weeks, you’ll probably begin to feel better. Soon, low-carb, high-fat eating will become easier for most people.

By week four, you can expect to see weight loss, especially if you’ve been physically active.

Different Types of Keto Diets


There are many variations of the keto diet and low-carb diets in general. With a low-carb diet, the percentage of your calories from carbohydrates is lower than what is normally advised for good health.

In addition to the modified keto diet, there’s a so-called dirty keto diet, which focuses less on nutritional quality from whole foods and more on adhering only to the macronutrient ratio. For example, instead of consuming healthy fats from avocados and fish, dirty keto allows less healthy fats, such as those found in bacon, burgers and other highly processed foods.

Can I Lose Weight on the Keto Diet?

Research suggests that the keto diet can be effective for short-term weight loss, but in the long run, it may not be any better than low-fat diets that allow for more carbs.

“It is not clear if the keto diet works or is safe in the long term as a weight loss diet," says Lana Nasrallah, manager of clinical nutrition at UNC Health, a not-for-profit integrated health care system based in Chapel Hill, North Carolina.

Short-Term Weight Loss


On the keto diet, your body will begin to rely on glycogen for energy, which is glucose stored in the liver and muscle for future use. Each gram of glycogen is bound to approximately 3 grams of water. This water is flushed out via increased urination or sweat. As a result, initial weight loss is typically a result of water loss.

In comparison to calorie-counting, low-fat diets, people who followed keto-type diets experienced greater weight loss and more beneficial health outcomes, according to a review of 53 clinical trials. Researchers concluded that low-carb, high-fat diets of unprocessed, whole foods are an acceptable, effective and safe approach to weight loss (1).

People on a keto diet have been reported to initially experience rapid weight loss of up to 10 pounds in two weeks or less, according to a collection of peer-reviewed medical education studies (3).

Weight Maintenance and Management


Due to the highly restrictive nature of the keto diet, experts do not recommend it for long-term weight maintenance and management. Such an approach may lead to vitamin and nutrient deficiencies.

“Any diet that discourages certain food groups, such as carbs, is not good for long-term weight loss,” says Lisa D. Ellis, a registered dietitian in private practice in Manhattan and White Plains, New York.

How to Get Started on the Keto Diet

Various websites can help you get started on the keto diet. You can also purchase a number of books about the keto diet.

Pantry


You’ll want to stock your pantry with these keto-friendly foods:

Food Diary


Keeping a food diary can help you adhere to the keto regimen. You can use an app to track your daily food consumption.

“Keeping a food diary is highly encouraged when first adopting a ketogenic diet, as this can help one determine if they are consuming the appropriate foods and ratio of macronutrients to truly induce ketosis,” Endicott says. “Ketone urine strips or blood test monitors can also be helpful for monitoring one’s state of ketosis. Food diaries can also help track symptoms that arise or progress over the course of following a new diet regimen.”

What Does the Keto Diet Cost?

The keto diet is not a commercial diet and should not cost you anything beyond the price of food and perhaps a book or two.

Is the Keto Diet Easy to Follow?

The keto diet is ranked No. 20 in Easiest Diets to Follow.

  • Budget friendly. Foods for this diet are easy to find at a typical grocery and don’t require expensive or specialty food items.

  • Gluten-free friendly. Recipes can be easily modified and still follow a gluten-free diet.

  • Halal friendly. Recipes can be easily modified and still follow a halal diet.

  • Kosher friendly. Recipes can be easily modified and still follow a kosher diet.

  • Low-carb. Foods on this diet are high in protein and healthy fats and low in carbs.


Experts say the keto diet is a restrictive eating regimen and is difficult to follow in the long run. To follow it, one must be educated on which foods contain carbs and have the skills and desire to prepare appetizing high-fat meals over the long term.

“To truly be in ketosis, you must consume 80% of your calories from fat, which, over time, can become boring, unappetizing and unsustainable,” Endicott says.

Who Should Not Try the Keto Diet?

Pregnant women, children who have not been medically advised to lose weight, people with certain types of cancer, people with heart disease, kidney or liver conditions and high-performing athletes should not try this diet. There are some concerns that following a keto diet for more than two years may have adverse effects, according to a recent review of studies. These issues can include (3):

  • Nutrient deficiencies.

  • Gastrointestinal upset, especially in the first few weeks. 

  • Kidney stones.

  • Heart disease. 

  • Muscle loss.

  • Cognitive decline.


The diet can also have a dramatic effect on insulin and reproductive hormones. The keto diet for people with diabetes is controversial, and some dietitians advise against it. A person with diabetes, especially someone taking insulin, requires careful medical monitoring at the very minimum.

Everyone interested in following a keto diet should consult a physician and registered dietitian before starting.

Pros

  • Coaching and/or group support available.

  • Convenient – grab and go options.

  • Has proven health benefits.

Cons

  • Lacks in-depth nutritional guidance.

  • Tedious portioning, meal planning or prep.

  • Potential for monotony unless you customize.

  • Eating out is limited.

  • Unsafe for some people.

  • Lots of rules to remember.

  • Could fall short nutritionally.

What Can I Eat? Do's and Don'ts of the Keto Diet

The keto diet calls for greatly curtailing your intake of carbs and consuming more fats.

Foods to Eat



Foods to Avoid (or Limit)


  • Alcohol.

  • Corn.

  • Desserts.

  • Sweets. 

  • Legumes, beans, peas and lentils. Though these are good sources of protein and generally considered very healthy food items, they contain too many carbs to conform to the keto diet's strict limit on carbohydrates.

  • Grains, including rice, pasta and oatmeal. There are too many carbs in grains to be keto.

  • Low-fat dairy products. The fat content of full-fat dairy makes it useful for keto dieters, but low-fat or skim products don't contain enough fat to balance out the milk sugars they contain.

  • Added sugars and sweeteners.

  • Sugary drinks.

  • Snack foods. Most items contain too many carbohydrates.

  • Starchy vegetables, such as potatoes and peas.


Vegan and Following the Keto Diet


Although difficult, it is possible to adhere to a vegan diet while following the keto diet. In a keto diet for vegans, you’ll need to rely on high-fat, plant-based foods, including coconut oil and nuts, for most of your calories. Choose coconut milk and cream, vegan cheese alternatives and ground flaxseed to replace dairy products and eggs. See all vegan diets.

Vegetarian and Following the Keto Diet


Following a vegetarian keto diet is possible. Vegetarians can select tempeh, tofu and seitan as protein sources while on the keto diet. Avocado, coconut and olive oils are healthy plant-based fats that will fit nicely into your diet. See all vegetarian diets.

Gluten Free and Following the Keto Diet


When you eliminate carbs on the keto diet, you also rid your menu of most gluten-containing foods. However, you’ll still need to check every ingredient list on processed foods – such as keto-friendly salad dressings, soups or seasonings – that you incorporate into your diet. See all gluten-free diets.

Halal and Following the Keto Diet


You’ll be able to find halal-compliant meat and poultry at a halal butcher or some national supermarket chains. You will also need to seek out halal cheese (from cows milked by hand). See all halal diets.

Kosher and Following the Keto Diet 


It will be easy to combine kosher and keto diets. However, because the keto diet is generally rich in butter, you’ll need to find suitable replacements, such as coconut oil, for dishes containing meat to avoid mixing meat and milk. See all kosher diets.

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