Keto Diet : Health Risks for Long Term

Following the keto diet for an extended period of time can be difficult, and even some of its top proponents warn against sticking to its strict guidelines (like cutting back carbohydrates to 50 grams a day or less) for more than 30 to 90 days. Other researchers warn that sticking to the diet long-term could even be dangerous. Here are a few reasons why.

Low-carb diets could lead to vitamin or mineral deficiencies

Limiting carbs to 50 grams a day or less likely means you’re cutting out unhealthy foods like white bread and refined sugar. But it also means you may have to cut back on fruits and certain vegetables, which are also sources of carbohydrates.

That’s a concern, says Annette Frain, RD, program director with the Weight Management Center at Wake Forest Baptist Health, especially if someone is spending more than a few weeks on this type of diet. “Fruits and vegetables are good for us; they’re high in antioxidants and full of vitamins and minerals,” she says. “If you eliminate those, you aren’t getting those nutrients over time.”

It may also be hard to get enough fiber while you’re cutting back so severely on carbohydrates, since whole grains are one of the biggest sources of this important nutrient. That can lead to digestion problems (ranging from constipation to diarrhea), bloating and weight gain, and even elevated cholesterol and blood pressure.

It may affect your athletic performance

There’s no shortage of athletes who have jumped on the keto bandwagon, but some researchers worry that they could actually be sabotaging their strength and fitness. In a recent study in the Journal of Sports Medicine and Physical Fitness, researchers found that participants performed worse on high-intensity cycling and running tasks after four days on a ketogenic diet compared to those who’d spent four days on a high-carb diet.

The body is in a more acidic state when it’s in ketosis, lead researcher Edward Weiss, PhD, associate professor of nutrition and dietetics at Saint Louis University, previously told Health, which may limit its ability to perform at peak levels.

Sure, keto can help athletes lose weight, which can be helpful for speed and endurance. “But I’m very concerned that people are attributing the benefits of weight loss to something specific in the ketogenic diet,” Weiss said. “In reality, the benefits of weight loss could be at least partially canceled out by reductions in performance.”

Relaxing the rules can cause weight re-gain

Because the keto diet is so strict, many variations of the diet recommend incorporating several stages. The first stage, usually the first one to three months, is extremely low-carb and allows for very few “cheat days,” if any at all. It also requires keeping close track of your carbohydrate and fat consumption to ensure your body is entering ketosis.

But then, people may transition to a more relaxed form of keto that allows for more carbohydrates or less monitoring—sometimes known as lazy keto, keto cycling, or “maintenance mode,” as Jenna Jameson has called it. The problem here, says Frain, is that weight re-gain is almost inevitable.

“Keto can be a great jump-start to weight loss, but the reality is that most people can't adhere to it for very long,” says Frain. “Often, people are going into ketosis and losing weight, then coming out and gaining it back and falling into this yo-yo pattern, and that’s not what we want.” In addition to being extremely frustrating, she says, these types of weight fluctuations are also linked to a higher risk of early death.

The type of weight you gain back is important as well. If you lost weight when you first started on keto, you likely lost some muscle mass along with fat tissue, says Kristen Kizer, RD, a nutritionist at Houston Methodist Medical Center. Now, since you’re following a high-fat diet, you will probably gain back more fat and less lean muscle—which not only looks and feels different on the body, but also burns calories at a slower rate. This can affect your metabolism and make it more difficult to lose weight again in the future.

It may also damage blood vessels

Enjoying a “cheat day” in the short-term on the ketogenic diet can also have long-term consequences, say researchers from the University of British Columbia. In a recent study published in Nutrients, they found that indulging in a high-sugar treat (like a large bottle of soda) while on a high-fat, low-carb diet can actually damage blood vessels.

“My concern is that many of the people going on a keto diet—whether it’s to lose weight, to treat type 2 diabetes, or some other health reason—may be undoing some of the positive impacts on their blood vessels if they suddenly blast them with glucose,” said senior author Jonathan Little, associate professor in the School of Health and Exercise Sciences, in a press release. “Our data suggests a ketogenic diet is not something you do for six days a week and take Saturday off."

Too much fat can raise chronic disease risk

Health experts worry about how a long-term keto-style diet can affect the heart and arteries. A not-yet-published study, presented at the American College of Cardiology’s annual Scientific Session, found that people on low-carb diets are more likely to develop atrial fibrillation (AFib) compared to those who eat moderate amounts of carbohydrates. AFib is the most common heart rhythm disorder and raises the risk of stroke and heart failure.

It’s not just the heart they’re worried about either. Research presented earlier this year at the European Society of Cardiology Congress found that people who followed low-carb, high-fat diets had an increased risk of dying from cancer and all other causes during the study period. And a recent study in the Lancet also found that low-carb dieters who consumed large amounts of meat and dairy had a higher risk of early death compared to those who consumed carbs in moderation or who consumed mostly plant-based protein.

Most of this research, it’s worth pointing out, is still observational—meaning that it’s only been able to find associations with certain health outcomes and not cause-and-effect relationships. Frain says that, overall, there’s not enough long-term research to know exactly what the ketogenic diet does to the body over an extended period of time—or why it seems to affect some people differently than others.

But she advises anyone who’s thinking about trying keto to strive for balance, not for extremes. “It’s important to look at what you’re missing in a diet and what is really sustainable for you,” she says. “You want to make sure you have satisfaction and satiety from the foods you’re eating and that you feel good and are getting great nutrition from a variety of foods. That’s what will help you keep it up and keep the weight off.”

While heart disease is still the number-one killer in the United States, it’s also no longer a guaranteed death sentence, thanks to newer medications, improved surgical techniques, and better understanding of the disease.

Society as a whole has also gotten better at preventing heart disease. A 2018 study in the journal Circulation found that the overall rate of heart disease in the U.S. had declined 38% since 1990. Other developed countries have seen even greater reductions.

But these improvements haven’t benefited everyone equally—and one new study shows a troubling trend among young people, and young women, in particular. When researchers looked at hospitalization rates for heart attacks between 1995 and 2014, they found that those numbers had steadily increased among people ages 35 to 54. More specifically, hospitalization rates remained relatively stable among men in this age group but increased significantly (from about 21% to 31%) among women.

The findings, published last month in Circulation, aren’t the first to suggest that young women are being left behind when it comes to advancements in heart disease treatment and prevention. Now, doctors are trying to figure out why.

For Young Women Disturbing Heart Trends

Scientists can’t say for sure what’s causing an increase in heart disease among young women, but they do have some ideas. Last month’s study found that not only had hospitalization rates for heart attacks increased among young people since 1995, but that hypertension and diabetes rates had increased as well. The young women in the study were also more likely to be black than the young men, suggesting that heart disease is hitting young black women especially hard.

The study didn’t look at patients’ body mass indexes, but co-author Melissa Caughey, PhD, a research instructor at UNC School of Medicine, notes that hypertension and diabetes tend to be associated with obesity.

“We know that there’s an obesity epidemic going on in the United States, and we know that women—especially black women—tend to have higher obesity rates than men,” Caughey tells Health. “It may be that these are actionable areas where physicians could do better to manage risk factors in these high-risk patients.”

Another interesting finding was that, compared to the young men in the study, the young women were less likely to have previously been treated for conditions like high blood pressure, high cholesterol, or stroke. This suggests that women are being under-treated for heart disease risk factors, wrote Viola Vaccarino, MD, PhD, an epidemiologist at Emory University, in a commentary published along with the study. Prevention guidelines may also underestimate risk among this age group, she added.

“Notably, there was no indication that the sex-related treatment gap improved between 1995 and 2014; if anything, there was a tendency for the disparities to worsen over time," wrote Dr. Vaccarino.

Another challenge is that women tend to experience heart attacks differently than men—so they, and their doctors, may not even recognize it when it’s happening, and their treatment may suffer as a result.

“Traditionally, a heart attack is described as the man clutching his chest and suddenly falling out of his chair,” says David Goff, MD, director of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute. “But heart attacks are seldom that dramatic, especially for women.” Women are more likely to report back pain, nausea, sweating, lightheadedness, or dizziness, Dr. Goff tells Health, rather than chest pains.

“When women present with these symptoms, the sad reality is that too often, the health care system doesn’t think about heart attacks first,” he says. “Women might be told that it’s anxiety or it’s gastroesophageal reflux or some other problem, because physicians still don’t know to look for heart problems.”

Things to be Changed

The new Circulation study did find some promising trends. Young women in the study were less likely to smoke than their male counterparts and were more likely to have health insurance. Indeed, says Dr. Goff, the decline in smoking rates over the last 50 years has been a big part of the overall decline in heart disease across all age groups.

Caughey stresses that the overall risk of heart disease for young women “remains quite low,” and that it increases significantly after menopause. “I don’t think this is anything for young women to panic over, but I do think it’s a warning sign that maybe women of this generation are not as healthy as those of previous generations were.”

Dr. Goff paints a slightly more concerning picture. “One out of four women in our country will die of heart disease, and 60% will have a major cardiovascular event before they die,” he says. “This means that none of us can really ignore our heart health—whether you’re older and overweight or you’re young and lean and otherwise healthy.”

Young women can improve their lifestyle and decrease their risk for heart disease by getting more physical activity, eating a healthier diet, and avoiding both first- and secondhand smoke, says Caughey. “And even if you’re already doing that, you should still know your numbers and check in every year or so with your doctor,” she adds.

Ultimately, experts say, doctors need to watch young women for symptoms of heart disease, so they can be diagnosed and treated before their conditions worsen. Doctors also need to pay attention to risk factors that could make young women more vulnerable to heart attacks and other forms of heart disease in the future.

For example, Dr. Vaccarino wrote, young women who have heart attacks are more likely than men to have depression or post-traumatic stress disorder, to report high levels of stress and more life adversities, and to fall into lower education and income brackets. Female-specific conditions like polycystic ovary syndrome (PCOS), premature menopause, or a history of preeclampsia may also play a role in heart disease risk.

“Younger adults, and women in particular, have been inadequately studied in cardiovascular research,” Dr. Vaccarino wrote. “It is now time to pay attention to this group to optimize prevention strategies and promote cardiovascular health among women.”