The keto diet is a highly restrictive eating plan that is touted as a way to lose weight and that is verified by some research. But that research only covers those on the plan for a short period of time. Research on long-term effects is limited, and this type of diet should always be kept short. Nutrition and health experts warn that any unbalanced diet can have hidden long-term dangers.
The keto diet requires at least 70% of daily calories to come from fat, about 25% from protein and only 5% to 10% from carbohydrates. Normally, cells in the body use blood sugar (glucose), which is created from carbohydrates, for energy. The keto diet drastically restricts carbs, so that, without any glucose, cells begin breaking down stored fat into chemicals called ketones. This process is known as ketosis. Once the body has entered ketosis, it will continue to generate and use ketones for energy until carbs re-enter the system. According to Harvard Health, ketosis usually happens after two to four days of eating fewer than 20 to 50 grams of carbohydrates a day, though each person is different and some need even more restricted carbs to fully enter ketosis.
In the short term, this process can indeed lead to weight loss. It may also have favorable effects on cardiovascular risk factors such as blood pressure, cholesterol and blood sugar levels, according to a 2012 study in Obesity Reviews.
But the long-range jury is still out. This is mainly because the keto diet is nearly impossible to follow long term. Carbs are a staple in our diet. In fact, the 2015-2020 Dietary Guidelines for Americans, produced by the U.S. Department of Health and Human Services and Department of Agriculture, finds that more than half of all Americans eat at least the recommended amount of total grains each day, and almost three-fourths eat more than the suggested amount of added sugars each day.
A keto diet is a major change in most people’s eating habits. It’s also an unpleasant change, as many of our favorite foods, including bread, pasta, cereal, sweet fruits and starchy vegetables, are forbidden.
Even if sticking to the keto diet for a long period was easier, that may not be a good choice because those who follow this eating plan longer are at added risk for some serious health problems.
The first symptoms of keto’s adverse effects are so well known they even have a name. “Some people report flu-like symptoms within the first few days of initiating the keto diet, which is often referred to as the keto flu,” says Kristen Smith, a registered dietitian and the bariatric surgery coordinator for Piedmont Healthcare in Atlanta.
Keto flu symptoms include:
The National Institutes of Health reports that long-term effects (more than two years) of following the keto diet are not known. But the dangers of any highly restrictive diet such as this are.
First is the potential for vitamin and mineral deficiencies that result when a diet is not well-balanced. The Academy of Nutrition and Dietetics says that, when limiting carbs, nutrient-rich vegetables and fruits are cut from the diet, so levels of vitamins A, C and K and folate usually are insufficient. Such deficiencies can cause many symptoms and illnesses, some mild and some severe and perhaps life-threatening.
According to the Academy of Nutrition and Dietetics, the high-fat content of the keto diet is “very controversial.” Most people are well aware that a vast amount of research has linked diets high in saturated fat with an increased risk for heart disease, diabetes, cancer and many other chronic health problems.
A high-fat, high-protein diet can also lead to:
- Kidney stones.
- Fatty liver disease.
- Hypoproteinemia (low levels of protein in the blood).
- Higher levels of low-density lipoprotein (the “bad” cholesterol).
Who Should Avoid a Keto Diet?
The NIH says that eating a keto diet is not recommended for those with:
- Pancreatic disease.
- Liver conditions.
- Thyroid problems.
- Disorders of fat metabolism.
- Eating disorders or a history of eating disorders.
- Gallbladder disease or those who have had their gallbladders removed.
In addition, the NIH says that those suffering from diabetes and taking insulin or oral hypoglycemic medication may suffer severe hypoglycemia if the medications are not adjusted before starting this diet. It recommends close monitoring of kidney functions while on a ketogenic diet.
Smith also warns against the diet for psychological reasons. “For some individuals, restricting entire food groups may lead to an unhealthy relationship with food, which can lead to disordered eating habits,” she says.
And if all this isn’t enough, know that you might be arrested for DUI – driving under the influence of ketosis. Though rare, ketosis can produce isopropanol, which can give a false positive alcohol breath test result.
For all these reasons and more, most dietitians warn their clients to steer clear of the keto diet. Though it may help you lose a little weight, “there is no scientific backing for it being safe and effective long term,” says Abby Greenspun, a registered dietitian in Westport, Connecticut. “I don’t see any reason to do it ever. I never recommend it for any of my clients, and I don’t know any dietitians who would.”