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Ketogenic Diet

What is a ketogenic diet?

A ketogenic diet is a high fat, moderate protein, and very low carbohydrate diet. The diet has been used since 1921 to treat pediatric epilepsy and has been popularized for rapid weight loss.

Wait. How does a high fat, very low carb diet help with weight loss?

It seems counterintuitive that we lose weight and body fat by eating fat. But the key to weight loss in a ketogenic diet is not so much about what we eat, it’s about what we don’t eat. Do not eat a lot of carbs to lose weight. A little physiology to explain:

High carbs = fat deposit

Carbohydrates are our bodies’ preferred energy source. When we eat sugars and starches, the carbs get broken down into glucose. Circulating glucose signals insulin release. Among its many functions, insulin helps deposit unused glucose into fat cells. So long as there’s unused glucose circulating, insulin will keep storing the excess in fat cells.

Very low carbs = burn fat

The ketogenic diet emphasizes low carbohydrate intake of less than 50 grams per day. Insulin is significantly reduced on this very low carb diet. Low insulin, along with other hormones signals our bodies to burn fat for energy.

In a ketogenic diet, so long as we maintain a very low carb diet with only moderate protein, our body will turn to alternative energy sources (ketone bodies) and burn fat to meet its metabolic demands. People on a ketogenic diet initially experience rapid weight loss up to ten pounds in two weeks or less.

So what does a ketogenic diet look like?

Meals on a ketogenic diet should consist of approximately:

  • Fat: 55% to 60% (Natural fats and oils such as olive oil, oily fish, and avocados)

  • Protein: 30% to 35% (Unprocessed meat, egg, seafood)

  • Carbs: 5% to 10% (Fresh vegetables)

There are no restrictions on overall daily calories or fat intake. Carbohydrates are restricted. And since the protein we eat can be converted into glucose for energy by the liver, the ketogenic diet also limits daily protein intake to one gram per pound of body weight.

Proceed with caution

The ketogenic diet is a rapid weight loss option for healthy individuals. The short term effects (up to two years) of the ketogenic diet have been well reported but the long term health effects are not clear.

People who go on a ketogenic diet may complain of “keto flu.” These symptoms include:

  • Nausea

  • Vomiting

  • Headache

  • Fatigue

  • Dizziness

  • Insomnia

  • Constipation

Fluid and electrolyte intake help with these symptoms. Symptoms typically resolve after a few weeks.

For those who can tolerate this very restricted diet, the long term adverse effects may include kidney stones, fatty liver, low levels of protein in the blood, and vitamin and mineral deficiencies.

The ketogenic diet is not appropriate for everyone. People with liver problems, kidney problems, disorders of fat metabolism, eating disorders, and certain metabolic diseases should not be on this diet. Diabetics should have their diabetes medication adjusted by their physician before starting the diet.

If you’re considering the ketogenic diet for weight loss, check in with your doctor to see if this high fat, moderate, and very low carb diet is appropriate for you.


Masood W, Annamaraju P, Uppaluri KR. Ketogenic Diet. 2020 Jun 22

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