Keto Diet : Risk of Health

It’s easy to see why a diet that promises quick results—and that technically allows you to still enjoy foods like burgers and cheese—would be so tempting. But before you try it, it’s important to realize that keto can also have its downsides and that there’s a lot health experts still don’t know about its long-term effects on the body.

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.

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.

here’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.”

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.

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."

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.”

Take a Walk After Eat : A Case Study

At the end of a long day, it’s tempting to dive into your social feeds or Netflix queue the minute you’ve finished eating. But back before screens bogarted all our free time, an after-dinner stroll was a popular activity and one associated with improved health and digestion. “Italians have been walking after meals for centuries,” says Loretta DiPietro, a professor of exercise science at George Washington University’s Milken Institute School of Public Health, “so it must be good.”

Research backs this up. One small study co-authored by DiPietro found that when older adults at risk for type-2 diabetes walked on a treadmill for 15 minutes after a meal, they had smaller blood sugar spikes in the hours afterwards. In fact, the researchers found that these short post-meal walks were even more effective at lowering blood sugar after dinner than a single 45-minute walk taken at mid-morning or late in the afternoon.

The human digestive system converts food into the sugar glucose, which is one of the body’s primary energy sources—so after a meal, glucose floods a person’s bloodstream. Hormones like insulin help pull that glucose into cells, either to be used immediately or stored away for later use. But for people with diabetes and impaired insulin activity, too much glucose can remain in the blood, which can cause or contribute to heart disease, stroke, kidney disease and other health problems.

“Insulin secretion in response to a meal tends to wane later in the day, and this is especially so in older people,” DiPietro says. She points out that many of us eat our largest meal of the day in the evening, and we also tend to sit around afterward. As a result, “blood glucose levels will rise very high and will stay elevated for hours,” she says.

What good does walking do? “The muscles we use to walk use glucose as energy, drawing it out of circulation and therefore reducing how much is floating around,” says Andrew Reynolds, a postdoctoral research fellow at the University of Otago in New Zealand.

Reynolds coauthored a 2016 study of people with type-2 diabetes and found that just 10 minutes of walking after a meal helped control their blood sugar levels. “We saw the biggest differences with walking after dinner time,” compared to other times of the day, Reynolds says. Like DiPietro, he says many people just sit around in the evenings, and this may be especially bad because the body’s ability to manage blood sugar at that time of day is weakest. “Getting up and moving around at that time was very effective,” he says.

Along with combatting surges in blood sugar, a little post-meal movement may also aid digestion. “Exercise stimulates peristalsis, which is the process of moving digested food through the GI tract,” says Sheri Colberg-Ochs, a diabetes and exercise researcher at Old Dominion University. Her research has found that a post-meal walk is much more effective than a pre-meal walk for controlling blood sugar.

More research has found that walking helps speed up the time it takes food to move from the stomach into the small intestines. This could help improve satiety after eating. There’s also evidence that links this type of faster digestion with lower rates of heartburn and other reflux symptoms.

Walking isn’t the only type of post-meal exercise that provides these benefits. “Whether it is resistance exercise or aerobic exercise, both have a similar impact on lowering blood glucose levels,” says Jill Kanaley, a professor of nutrition and exercise physiology at the University of Missouri. One small study by Kanaley and others found that for people with obesity and type-2 diabetes, doing a weight training session with leg presses, calf raises, chest flies and back extensions 45 minutes after dinner lowered their triglycerides and blood sugar for a short time—and improved their wellbeing.

But more isn’t necessarily better when it comes to post-eating exercise. There’s some evidence that vigorous forms of training may delay digestion after a meal. “Exercising muscles pull more of the blood flow their way during activity, and the GI tract gets relatively less,” Colberg-Ochs says. “That actually slows down the digestion of food in your stomach during the activity.” Most of the research on post-meal physical activity suggests that moderate intensities—think fast walking or biking—are best. “Anything but really intense exercise would probably work equally well,” she adds.

As far as timing goes, try to move your body within an hour of eating—and the sooner the better. Colberg-Ochs says glucose tends to peak 72 minutes after food intake, so you’d want to get moving well before then.

Even if you can only fit in a quick 10-minute walk, it’ll be worth it. Apart from the perks mentioned here, more research has linked short bouts of walking with benefits like lower blood pressure and a reduced risk for depression.