The ketogenic diet, often called the keto diet, is a low-carbohydrate, high-fat eating plan that has become popular for weight loss and blood sugar management. While some people may see short-term results, the diet can also be restrictive and may not be safe or sustainable for everyone.
Before starting keto, it’s important to understand how it works, what foods are allowed and the potential risks and side effects. A balanced eating plan that fits your lifestyle and health needs is often easier to maintain long term.
What is the keto diet?
The keto diet is a very low-carbohydrate eating plan that focuses on high amounts of fat, moderate protein and minimal carbs.
Normally, your body uses carbohydrates as its main source of energy. When carb intake drops very low, your body begins breaking down fat for fuel instead. This process is called ketosis.
Most keto diets include:
- 70% to 80% fat
- 10% to 20% protein
- 5% to 10% carbohydrates
The keto diet was originally developed to help manage epilepsy. Today, many people try it for weight loss or blood sugar control.
How does ketosis work?
When you eat fewer carbohydrates, your body’s glucose stores become depleted. In response, your liver breaks down fat into substances called ketones, which your body can use for energy.
Ketosis may help some people lose weight because the body relies more heavily on stored fat for fuel. Some people also feel less hungry on a keto diet because fats and proteins can help you feel full longer.
However, staying in ketosis requires strict carb limits, which can be difficult to maintain over time.
What foods can you eat on keto?
People following a keto diet typically eat foods that are high in fat and low in carbohydrates.
Foods commonly included on keto
- Avocados
- Olive oil and other plant oils
- Butter
- Cheese
- Nuts and seeds
- Fatty fish
- Eggs
- Meat and poultry
- Full-fat dairy products
- Low-carb vegetables such as:
- Leafy greens
- Broccoli
- Zucchini
- Cucumbers
- Asparagus
- Bell peppers
What foods are limited or avoided on keto?
Because the keto diet severely limits carbohydrates, many foods are restricted.
Foods usually avoided on keto
- Bread
- Pasta
- Rice
- Cereals
- Chips and crackers
- Most baked goods
- Beans and legumes
- Potatoes and other starchy vegetables
- Most fruits
- Sugary drinks
- Candy and desserts
- Honey, syrup and sugar
- Beer and many alcoholic beverages
Even healthy foods like bananas, oatmeal and beans may exceed the daily carb limit on keto.
Potential benefits of the keto diet
Some people may experience short-term benefits on the keto diet.
Weight loss
Reducing carbohydrates may lead to weight loss, especially in the early stages of the diet. Part of this may be due to water loss and reduced calorie intake.
Reduced appetite
High-fat and high-protein foods may help some people feel fuller longer, which can reduce snacking and overeating.
Blood sugar management
Some studies suggest keto may help improve blood sugar levels in certain people with type 2 diabetes. However, medication adjustments may be needed, so medical guidance is important.
Medical uses
The ketogenic diet continues to be used in some medical settings, particularly for epilepsy treatment.
Risks and side effects of the keto diet
The keto diet can cause side effects, especially during the first few weeks.
Keto flu
Some people experience flu-like symptoms as the body adjusts to ketosis. Symptoms may include:
- Headaches
- Fatigue
- Nausea
- Dizziness
- Irritability
- Brain fog
These symptoms are sometimes called the “keto flu.”
Constipation
Because keto limits many fruits, whole grains and fiber-rich foods, constipation can become a problem for some people.
Nutrient deficiencies
Restricting entire food groups may make it harder to get enough vitamins, minerals and fiber.
Kidney concerns
High intake of animal proteins and certain fats may increase the risk of kidney stones in some people.
Cholesterol changes
Some people may see increases in LDL cholesterol levels while following a keto diet.
Difficulty maintaining the diet.
The keto diet can be very restrictive. Many people find it difficult to follow long term because it limits common foods and social eating situations.
Who should avoid the keto diet?
The keto diet may not be appropriate for everyone.
Talk to your health care provider before trying keto, especially if you:
- Have kidney disease
- Have liver disease
- Take insulin or diabetes medications
- Are pregnant or breastfeeding
- Have a history of eating disorders
- Have certain heart conditions
A provider or registered dietitian can help determine whether keto is safe for your health needs.
Is keto better than a regular low-carb diet?
Not necessarily.
A standard low-carb diet is often less restrictive than keto and may be easier to maintain long term. Many people can still lose weight and improve overall health without needing to stay in ketosis.
The best eating plan is usually one you can follow consistently while still meeting your nutritional needs.
Is the keto diet safe long term?
Researchers are still studying the long-term effects of the keto diet.
While some people successfully follow keto for extended periods, others may struggle with side effects, nutritional balance or sustainability. Many health experts recommend focusing on balanced eating habits that include fruits, vegetables, whole grains, lean proteins and healthy fats.
Long-term health goals are often better supported by eating patterns that are realistic and sustainable.
When should you talk to a health care provider?
Talk to your provider before making major dietary changes, especially if you have a chronic health condition or take prescription medications.
A registered dietitian can also help you create a personalized eating plan that supports:
- Weight management
- Heart health
- Blood sugar control
- Athletic performance
- Healthy aging
Frequently asked questions about the keto diet
Is the keto diet safe?
It may be safe for some people in the short term, but it is not appropriate for everyone.
People with certain medical conditions should speak with a health care provider before starting keto.
How fast do you lose weight on keto?
Some people lose weight quickly at first, partly due to water loss. Long-term results vary from person to person.
What is keto flu?
“Keto flu” refers to temporary symptoms that can happen as your body adjusts to ketosis. Symptoms may include headaches, fatigue and nausea.
Can keto raise cholesterol?
Yes. Some people experience increases in LDL cholesterol levels while following a keto diet.
Can you eat fruit on keto?
Some lower-carb fruits may fit into a keto diet in small amounts, but many fruits are limited because of their natural sugar content.
What happens when you stop keto?
When you begin eating more carbohydrates again, your body shifts out of ketosis. Some people regain weight if old eating habits return.
Bottom line
The keto diet may help some people lose weight or manage certain health conditions in the short term, but it is not a one-size-fits-all solution. Because it is highly restrictive, it can be difficult to maintain and may carry risks for some people.
Before starting keto or any major eating plan, talk with a Banner Health provider or a registered dietitian to make sure it aligns with your health goals and medical needs.
