If You're Thinking About the Keto Diet, Read This First

keto diet

Want to shed some pounds and thinking about the ketogenic diet? There may be better ways to lose weight and keep it off.

The ketogenic diet is a high-fat, moderate-protein, low-carb diet that has been used since the 1920s to treat difficult-to-control epilepsy in children, says registered dietitian Meghann Featherstun, MS, RD, CSSD, LD. Ms. Featherstun is a clinical dietitian and wellness coach at University Hospitals and is a board-certified specialist in sports dietetics.

The standard keto diet is 75 percent fat, 20 percent protein and 5 percent carbohydrates. The diet forces the body to burn slower-burning fats – and the body’s stored fats – rather than rely on carbohydrates in the bloodstream as an energy source. With the keto diet, your body turns dietary and stored body fat into ketones in the liver, which supplies energy for the brain, a metabolic state called ketosis.

Research has shown that the keto diet can have benefits for other health conditions, including prediabetes, metabolic syndrome, heart disease, cancer, Alzheimer’s disease and Parkinson’s disease – and to lose weight, Ms. Featherstun says. But there are several caveats to consider if you’re considering the keto diet in order to lose weight.

Difficult to Follow

Many people don’t realize in considering the keto diet that most fruits and vegetables – and many other foods thought of primarily as proteins or fats – contain some carbohydrates too, Ms. Featherstun says.

For example:

  • 1 cup of milk – which most people would consider a protein – has 12 grams of carbohydrates.
  • A small piece of fruit such as an apple, orange or nectarine, has 15 grams of carbohydrates.
  • A cup and a half of vegetables such as green beans, broccoli or carrots, has 15 grams of carbohydrates
  • One healthy fat rich avocado has 17 grams of carbohydrates.

So the grams can pile up even if you avoid foods primarily considered carbohydrates such as bread, pasta and sugar.

Also, the keto diet is not a high-protein diet, Ms. Featherstun says. Eating too much protein can keep you from reaching ketosis. The emphasis in this diet is on high fat foods – ideally, heart-healthy fats would be eaten such as avocados, nuts, seeds, olive oil, fatty fish, and avocado oil.

Consider the Side Effects

The keto diet’s side effects are also something to consider, Ms. Featherstun says.

“Keto flu,” “keto brain” and “keto fog” are common side effects of the diet and comprise a number of symptoms such as poor concentration, headache, irritability, weakness, dizziness or muscle soreness.

These side effects can last for two to three weeks – more if you go off the diet for a couple of days, Ms. Featherstun says. That’s because it takes two to three weeks to adjust to the switch to fat-burning mode, and if you go off the diet, your body will revert to carb-burning mode. Then you have to go through the symptom phase all over again to get back into ketosis.

“Once you go back to your former eating habits, even if it’s just a couple days, you’ve just been crabby for two weeks for no good reason,” she says.

And if you plan to exercise to lose weight faster, know that the keto diet can greatly decrease your ability to work out intensely. Carbs are a quick-burning fuel and readily available, while fat is a slow-burning fuel that the body cannot access quite as easily.

“For someone who is starting out physical activity in order to lose weight, higher intensity exercise is going to feel much harder than it needs to feel,” Ms. Featherstun says.

Don’t Choose a ‘Diet’

The fact that so many foods contain carbohydrates, plus the side effects, makes this an extreme way of eating for most people, Ms. Featherstun says.

A ketogenic diet makes sense for certain people if they are able to consistently follow the high-fat, moderate protein, low-carb lifestyle: someone with Type 2 diabetes; someone who is pre-diabetic and trying to avoid developing diabetes; or someone with epilepsy trying to control their disease, Ms. Featherstun says. These people can be highly motivated because of a serious medical condition.

But for those of us interested in dropping weight, “the practicality of correctly following the diet long enough to reap the benefit is hard for the typical American,” she says. “I’m seeing people trying this and having difficulty sticking with the diet and then gain back any initial weight loss plus more. It’s a tough cycle.”

The best way to lose weight, she says, is by eating a wide variety of fresh fruits and vegetables, whole grains and lean meats and more plant-based proteins in appropriate amounts for your activity level -- and avoiding junk, highly processed or sugary foods. That way of eating is more reasonable and can be sustained for a lifetime, she says.

“The best diet is the diet that you can adhere to,” Ms. Featherstun says. “Any change has to be one you can live with for the foreseeable future.”

If You Must Try the Keto Diet

“The keto diet is rarely something I recommend for weight loss,” Ms. Featherstun says. But if you feel this eating style might work well for you, she says, be sure to work with a registered dietitian or healthcare provider to make sure you’re doing it in a healthy way.

She also advises finding accurate and precise nutritional information to ensure you have the nutrition knowledge to meet the diet’s high-fat, moderate-protein, low-carb guidelines. A phone app can help, she says, or you can find nutritional information on the U.S. Department of Agriculture's National Nutrient Database.

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