Medically Reviewed by Melinda Ratini, MS, DO on September 13, 2023
Written by Shishira SreenivasThe ketogenic diet, or keto for short, is a high-fat, moderate-protein, low-carbohydrate diet that has gained a lot of attention as a weight loss method in recent years. But does it really work? If you're thinking about trying the keto diet, here's a look at what to expect if you're a beginner.
The keto diet may sound trendy, but it has been around for a while. It first surfaced in the 1920s. Originally, doctors recommended it to help with conditions like epilepsy and diabetes. But today, some people use the keto diet to lose weight.
For many Americans, carbs like breads, pasta, or potatoes make up more than 50% of their daily diet. Your body breaks down the glucose (sugars) found in carbs to fuel your body with energy.
In the keto diet, the goal is to swap out the glucose calories with fat. In a typical keto diet, your nutrition centers on fatty foods. They'll make up anywhere from 60% to 80% of your daily calories. Proteins make up 15% to 20%. Carbs are restricted to no more than 50 grams. This makes it quite a restrictive diet.
Studies show that those who follow the low-carb keto diet are more likely to lose weight within the first 3 to 6 months than they would if they followed a more balanced diet. But because the keto diet calls for drastic changes in your daily diet, it's best to ask your doctor or a nutritionist if it's right for you before you get started.
When you're on the keto diet, you’re eating too few carbs to support your body's energy needs. As a result, your body turns to burning your stores of body fat to fuel your energy.
When your body burns body fat for fuel, it produces ketones, substances made in your liver. Your body enters a metabolic state called "ketosis."
If you follow the keto diet strictly, your body will reach ketosis in about 4 days. You will likely even see several pounds of weight loss the first week.
If you're planning to start the keto diet, keep in mind that there are several types. Each one focuses on slight changes in the proportion of fat, protein, and carbs in your daily diet.
The types of keto diet include:
Standard ketogenic diet (SKD). This is a very low-carb, moderate-protein, high-fat diet. It typically contains 70% fat, 20% protein, and only 10% carbs in your daily diet.
Cyclical ketogenic diet (CKD). This involves periods of higher-carb "refeeds," such as 5 ketogenic days followed by 2 high-carb days.
Targeted ketogenic diet (TKD). This diet allows you to add carbs around intense workouts.
High-protein ketogenic diet (HPKD). It's similar to the SKD, but you can eat more protein. The ratio is usually 60% fat, 35% protein, and 5% carbs.
The standard and high-protein diets have been researched and studied the most. They're also the most common. The cyclical and targeted keto diets are recent additions and are mostly used by athletes or bodybuilders
At first, the keto diet was primarily used as a way to help people with seizures. Over time, experts applied the benefits to several other health conditions, including:
The keto diet has been highly effective for certain conditions, especially type 2 diabetes. One study looked at the before-and-after keto diet results for 349 adults with type 2 diabetes over a period of 1 year. It reversed diabetes in about 60% of the participants. The keto diet also helped many of those in the study to lower their dependence on prescription insulin drugs.
If you have a health condition, it's best to talk to your doctor before you start the keto diet.
To start the keto diet, you may have to toss a few things out of your pantry and add certain high-fat food sources to include in your daily meals.
Talk to your doctor or a nutritionist about what will work best for you. This is especially important if you have other dietary restrictions, such as being a vegan, vegetarian, or having certain food allergies. Experts can help you find alternatives or substitutes and come up with a meal plan that best suits your needs.
Before you start changing your meals, here are some questions you should consider or ask your doctor:
Some keto-friendly foods are:
For the 20 to 50 grams of carbs per day, choose non-starchy veggies like:
Foods to avoid or limit include starchy and high-carb foods like:
In terms of acceptable drinks on the keto diet, you can opt for unsweetened coffee or tea. Cut down on how much alcohol you drink. If you drink alcohol, choose low-carb liquors like tequila or vodka and use soda water as a mixer.
Keto-friendly snacks are a good balance of healthy fats and moderate protein with low-carb content. You can make some at home or use store-bought versions.
This includes snacks such as:
These snacks can help you manage your hunger between meals and stick to staying in ketosis in the long term.
While research shows that the keto diet helps some people lose weight or manage health conditions, the restrictive diet isn't a good idea for everyone. It may be harmful if you follow the diet incorrectly or without proper supervision.
The keto diet also affects each person differently. While some people can transition easily to the dietary changes, others may find that their body takes longer to adjust to the sudden changes.
It's important to get your cholesterol checked regularly. The keto diet may decrease cholesterol for some people, but it may increase cholesterol for others.
The low-carb part of the diet may have long-term consequences for some people. For many, cutting out carbs so suddenly and drastically can lead to what many popularly call the "keto flu." You may get flu-like symptoms as your body navigates switching from burning glucose to fat for energy.
Symptoms of keto flu include:
Usually the symptoms of keto flu kick in a day or two after you cut carbs from your daily diet. They may last up to a week or less, but in severe cases, they could last up to a month. If the symptoms are severe or persist, see your doctor or stop the diet.
To lessen the chances of getting the keto flu, start the diet slowly, stay hydrated, do only light exercises, and get plenty of rest as your body gets used to your new meal plan.
Another pitfall that experts warn about is that there are too many types of keto diet and it's easy to do it incorrectly. You may end up eating too many saturated fats instead of healthy fats that can put you at risk for high levels of bad cholesterol and heart disease. You may also not reach ketosis if you don't follow the diet properly.
The keto diet can also affect your gut health. That's because the diet mostly requires you to cut out nutrient-dense and fiber-rich foods like legumes, whole grains, starchy vegetables, and fruits. The studies on keto's effects on gut health are conflicting. There needs to be more research done on this topic.
Other side effects can include:
If you're planning to give the keto diet a try for the first time, ask your doctor, nutritionist, or dietitian if it's right for you. They'll help you come up with a tailored meal plan that may work best for you.
