Ketogenic Diets for Weight Loss

Keto diet fans say you can eat fat to lose weight

Fried fillet of beef with herb butter, peppercorns and rosemary in a pan
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A ketogenic diet, or keto diet, is a very low carbohydrate eating plan that forces the body to use fat rather than glucose as a primary energy source. Acids called ketones are produced as a result of this process. When ketone levels are high enough, the dieter is in a state of ketosis. Keto diets may be used to improve certain medical conditions such as epilepsy or neurologic illnesses. Some dieters also use ketogenic diets to lose weight.

The Ketogenic Diet for Weight Loss

Researchers and medical experts have used ketogenic diets since the 1920s to treat certain illnesses. But recently, dieters have started using keto diets for weight loss. The Atkins Diet popularized the idea of eating fat to lose fat and since many dieters have had success with the Atkins program, the trend has caught on.

So how does a keto diet work? Most ketogenic dieters consume about 70-75 percent of their calories from fat. They consume about 5-10 percent of calories from carbohydrate and the rest from protein. In short, keto dieters build most of their meals around fat sources like cheese, nuts, oils, fatty fish and meats.

When you restrict your intake of carbohydrates, your body runs out of its favorite source of fuel, glucose. The body can use protein for fuel, but if you decrease your intake of protein as well, the body is forced to use stored fat as it's primary source of fuel.

When you use fat for fuel, the body creates ketones. When the body begins using fat as it's primary source of fuel and you are producing ketones you are in a state of ketosis. Dieters can test for the presence of ketones using urine strips, blood strips or a new breath detection machine.

But ketones aren't produced right away when you start the diet and you have to be very strict with your eating plan to get into a state of ketosis.

Dr. Deborah Gordon, M.D. says that "most people take 5-10 days, but even then it's likely to be inconsistent unless they are strict with their diet."  

Dr. Gordon is a holistic physician who practices in Ashland, Oregon. She said she first recommended a ketogenic diet to a patient for medical reasons and that patient was successful on the plan. But she says when it is used for weight loss, results can be a mixed bag.

Does Ketogenic Weight Loss Work?

There is a lot of controversy about using ketogenic diets to lose weight. Some experts say that eating too much saturated fat in your diet can increase your risk of heart disease. But others say that reducing carbohydrate intake (especially in the form of empty calories) creates health gains. Not all experts are convinced that ketogenic diets are effective in the long-term.

"Most dieters will find that they lose weight in the short term when they go on a keto diet," says Jim White. White is a registered dietitian, owner of Jim White Fitness and Nutrition Studios and is a spokesperson for the Academy of Nutrition and Dietetics. He says that most dieters slim down initially on a keto diet because they lose water weight.

According to Jim, for every gram of carbohydrate you consume, your body holds on to 3 grams of water.

When you cut out all of the carbs, he says that the body also eliminates all that water as well. In addition, he says that limiting carbohydrate intake means that most dieters eat way less food in general. The result is that keto dieters consume fewer calories.

So what does the research say? Scientists have found that ketogenic diets often create short-term weight loss. But they don't exactly know why the fat loss occurs. Some researchers think that a high-fat diet helps dieters feel more satisfied and less interested in food. Others say that there are mechanisms in the brain that change when fat is used for fuel.

But most researchers agree that keto diets may be helpful for some, but are not a guaranteed path to sustained weight loss.

Keto Diet Side Effects

Many dieters struggle to stay on a ketogenic diet for up to six months or a year. This may be one of the reasons that long-term weight loss results are inconclusive. Ketogenic side effects can make the program hard to maintain.

"Very few people can stay on this diet for a long time," says Jim White. "Even though some people say they feel more energized, you can get very tired on this plan." He explains that carbohydrates are the brain's main source of fuel. Without them, we get foggy, irritated and start to feel bad.

And Dr. Gordon says that she sees some dieters struggle as well, especially women. "There is controversy as to whether low carb diets work well for women, and most of the patients I see who want to lose weight are women. She says that sticking to the eating plan is a problem. After the adjustment period, she says that about a third of her patients lose weight. The other dieters either don't see weight loss or they can't tell if the diet has been successful because of other complications.

Both Jim White and Dr.Gordon say that dieters can experience problems because of a lack of fiber in a ketogenic diet. When dieters eat almost no grains, very little fruit and limited vegetables they don't get many of the important nutrients, including fiber, that their bodies need to function.

Other side effects can include 

  • ketone flu ( a general feeling of fogginess) 
  • headaches
  • fatigue
  • generally feeling not well
  • bad breath
  • constipation
  • insomnia 
  • possible hormone dysregulation

Both experts acknowledge that keto diet side effects are more common in the beginning of the program. Dr. Gordon says that she may recommend intermittent ketosis to help manage the symptoms. On that plan , dieters practice twice weekly fasting for 24 hours or a 16-hour fast more frequently.

Lastly, a dangerous condition called ketoacidosis may occur if your ketone levels rise too much and the blood becomes acidic. The condition is most likely to happen in type 1 diabetics and can result in a diabetic coma. For this reason, experts recommend testing ketone levels on a regular basis.

How Many Carbs on a Ketogenic Diet?

If you're trying to lose weight on a keto diet, you may find conflicting recommendations for the number of carbs to eat on the plan. Some sources say that you should consume no more than 20 grams of carbohydrate per day to reach ketosis. Other sources recommend that you consume 20 grams of net carbs per day. Still others sources advise up to 50 grams of carbohydrate per day and many recommend no more than 5 percent of calories from carbs per day.

Confused? Dr. Gordon explains that the right number of carbs to eat on a keto diet can vary from person to person. She gives an example of a married couple who was using a ketogenic diet to lose weight. "She stayed in ketosis with no more than 1/4 cup of blueberries a day, his limit was 1 blueberry." So what does she recommend to her patients? "Everyone is different," she says, "so I encourage people to get down to 20-30 grams of net carbs with testing. Then they can modify their intake accordingly."

How Many Calories on a Keto Diet?

Since researchers don't fully understand how dieters lose weight on a ketogenic diet, it is unclear whether or not you should count calories on this eating plan.  A quick online search will reveal that some keto fans say you must count calories and carbs to lose weight and others say you can eat as much as you want as long as you maintain the correct carbohydrate intake.

So what do the experts say? "Macronutrients are very important on this diet because you have to drop carbs to get the body into ketosis," says Jim White. “But it is a calorie game too. It is a little unclear whether it is the body's use of ketones, the decrease in water weight, or the decrease of calories that makes weight loss happen. But it's probably a combination of all three.” 

If you decide to try a ketogenic diet for weight loss, keep in mind that you may have to experiment with the number of carbs and calories to find the right balance. And your weight may fluctuate during this time. Once you find the level that works for you, fill your kitchen with healthy keto diet foods and plan keto-friendly meals to reach your goal weight. Communicate with your health care provider or a registered dietitian if you experience symptoms that cause concern. 


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