The Ketogenic Diet for Weight Loss: Be Careful

Reviewed by: HU Medical Review Board | Last reviewed: August 2023

You may have heard about the popular ketogenic (keto) diet. It involves eating a lot of fat, a medium amount of protein, and very few carbohydrates. Eating this way changes the kind of fuel your body uses for energy. It also changes the way your body gets and uses that fuel. And it means leaving many healthy foods out of your diet.1-7

Your body is made to use carbohydrates for energy. On the keto diet, it must use something else. The idea is that without carbs, your body will use stored fat for energy. Your liver turns body fat into a fuel called ketones. These become the energy source for your heart, kidneys, muscles, brain, and body functions.1-7

Keto fans report losing a lot of weight. But there are few long-term studies about whether people keep the weight off. Also, weight loss is not the only thing that happens to your body when you adopt this diet. There are serious physical and mental effects to think about before you decide whether to try it.1-7

What happens besides weight loss?

At first, you are likely to have the “keto flu.” You may feel tired, dizzy, or sick to your stomach. You may have a headache. You may have trouble thinking, or “keto fog.” These effects can make it hard to complete daily tasks. They often pass after 2 to 4 weeks.1-3

To restrict carbohydrates, you avoid foods like whole grain breads, fruits, legumes, and starchy vegetables. But these foods are full of important vitamins, minerals, and fiber that your body needs. They also help protect against many health conditions, including:1-3

  • Heart disease
  • Diabetes
  • Cancer
  • Alzheimer’s disease
  • Malnourishment

When you do not eat enough carbohydrates, your body may not get all the nutrients it needs to stay healthy.1-3

What does the research say?

The best studies test large numbers of people over a long time. At this point, the only long-term keto studies are about treating epilepsy. That is why few experts recommend it. Also, some studies report serious concerns about the effects of the keto diet, such as increased risk of:1-5,7

  • Dehydration
  • Kidney stones and chronic kidney disease
  • Plaque in the arteries and stroke due to high “bad” cholesterol (LDL) levels
  • Liver disease
  • Diabetes (in the long term)
  • Pregnancy diabetes or birth defects in the infants of people who eat low-carb diets before and during pregnancy
  • Alzheimer’s disease

In some studies, few people stayed with the diet long term. And many people found it hard to keep the weight off after stopping keto.1-5,7

However, other studies promote the keto diet for short-term help with certain health issues. They found the diet can have positive effects including:3,6,8

  • Weight loss (first 6 to 12 months)
  • Appetite control
  • Blood sugar control
  • Healthy blood levels of neutral fats (triglycerides)
  • Increased “good” cholesterol (HDL)
  • At first, improved memory for a few people with Alzheimer’s disease
  • Improved stamina in sports
  • Stopping seizures in people with epilepsy when medicine does not work

How should I follow the keto diet?

If you are interested in the keto diet, it is important to consult a healthcare provider first. You will need to learn to keep track of your macronutrients (macros). You also may want to talk to a nutritionist to help you map out your meals.1-5,7

Keto diet plans vary in amounts of macros. Below is a sample daily diet for an average person who eats 2,000 calories per day.1-3,5

  • 75 to 80 percent of calories (1,500 to 1,600 calories) come from fat. This is about 165 to 178 grams per day.
  • 15 to 20 percent of calories (300 to 400 calories) come from protein. This is about 75 to 100 grams per day.
  • 5 to 10 percent of calories (80 to 160 calories) come from carbohydrates. This is about 26 to 52 grams per day.

Here are some types of foods keto includes:1

  • Dairy products such as butter, cream, cheddar or Gouda cheese, whole-milk plain Greek yogurt, cottage cheese, and sour cream
  • Eggs
  • Nuts and seeds
  • Olive, coconut, and avocado oils
  • Red meat, pork, poultry, and fatty fish such as salmon, tuna, and cod
  • Vegetables that grow above ground like zucchini, squash, tomatoes, and peppers

Before you begin, talk to your healthcare provider, do your homework, and consider the pros and cons of the keto diet. You can learn more about it on the internet. There you will find keto websites, diet plans, recipes, and shopping tips.

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