Keto may be the diet of the moment, but the high-fat, low-carb approach isn’t a good idea for everyone, all the time.
While the ketogenic diet may seem new and trendy, it’s actually been around since the 1920s as a treatment for epilepsy. and with helping folks drop those stubborn extra pounds.
“The Keto can certainly be effective for quick weight loss,” says Kim Yawitz, a dietitian in private practice in St. Louis. “Weight loss of up to 10 pounds in just a couple of weeks is common, although some of this is water weight.”
The ketogenic diet typically reduces carbohydrate intake to less than 50 grams per day — and calls for increased protein and fat intake, according to a review published in August 2013 in the European Journal of Clinical Nutrition. Roughly speaking, on keto you’ll get 70 to 80 percent of your calories from fat, about 20 percent from protein, and as little as 5 percent from carbs.
A review published in January 2015 in the Journal of Clinical Neurology found that only 45 percent of participants were able to follow the approach as prescribed. “The poor compliance was attributed to side effects, social isolation, and cravings,” says Yawitz. And some people in the study “reported the diet simply wasn’t helping them lose weight,” she adds. Brissette agrees with this line of thinking. “In my opinion, the keto diet isn’t sustainable and takes the joy and fun out of eating,” she says.
As you can see, there are many potential benefits and side effects of the ketogenic diet. Here, we’ll delve into 10 potential danger of the keto diet that any beginners considering the approach need to know.
1. Muscle Loss Is a Possible Side Effect of Keto
Small studies suggest that people on the ketogenic diet lose muscle even when they continue resistance training. This may be related to the fact that protein alone is less effective for muscle building than protein and carbohydrates together after exercise.” Meanwhile, according to a small study published in March 2018 in the journal Sports, people following the keto diet for three months lost about the same amount of body fat and had about the same muscle mass changes as people following normal diets. Yet the folks on keto did lose more leg muscle.
“Loss of muscle mass as we age has a number of serious consequences,” notes Nik. “Muscle is metabolically active and helps boost daily energy expenditure and mitigate age-related weight gain.” Losing muscle mass can also decrease functional strength and heighten the risk of falls, note Nik. Falls are the top cause of death from injury in older populations, according to the Institute of Medicine Division of Health Promotion and Disease Prevention.
2. Keto Can Put Stress on the Kidneys and Possibly Give You Kidney Stones
“If you’re going to do keto, there’s a better and a worse way to do it,” says Nik. “Loading your plate with meats, and especially processed meats may increase your risk for kidney stones and gout,” which is a painful type of arthritis. “High intake of animal proteins makes your urine more acidic and increases calcium and uric acid levels. This combination makes you more susceptible to kidney stones, while high uric acid can increase your risk for gout,” adds Nik.
And the ketogenic diet can be dangerous for people with kidney disease, as people with kidney disease need to follow an individualized diet as prescribed by their doctor. According to Davita Kidney Care, people with kidney disease often need to consume a low-protein diet, which may not align with the type of keto you’re following.
3. The Possibility of Low Blood Sugar Can Make Keto Risky for People With Diabetes
Carbohydrates help control blood sugar levels, which are of particular importance for people with diabetes. A study published in May 2018 in the journal Diabetic Medicine shows that while a keto diet may help control HbA1c levels (a two- to three-month average of blood sugar levels), the diet may also cause episodes of hypoglycemia which is a dangerous drop in blood sugar. Echoing many registered dietitians, the Lincoln, Nebraska–based sports dietitian Angie Asche RD, says she is “hesitant to recommend a ketogenic diet for individuals with type 1 diabetes.”
The best course of action is to proceed with caution and consult a professional before diving in. “If you have a medical condition or are on medications, you should always consult with your doctor
4. Because It’s Hard to Follow, Keto Can Lead to Yo-yo Dieting
“Rapid, significant weight loss is a common side effect of the keto diet because of the water losses that occur as carbohydrate stores are depleted,”
Nik says people following the diet have the best chance of keeping the weight off if they stay on it long term. And that’s not always easy to accomplish. The weight may come back if you go back to your regular eating habits. And regaining weight may lead to other negative effects. “Chronic yo-yo dieting appears to increase abdominal fat accumulation and diabetes risk,”
5. The Ketogenic Diet Can Lead to Dehydration and a Loss of Electrolytes
“Suddenly and drastically reducing carbohydrates sets your body up for a double whammy of sorts,” says Yawitz. “The brain’s favorite fuel is glucose, which is most easily created from carbohydrates. In very-low-carb diets, the brain has to adjust to using ketones from digested fats for energy. To add to this discomfort, your kidneys release more electrolytes as insulin levels fall.” Additionally, your total body water decreases as carbohydrates become depleted on a keto diet, notes Clark. The result? What’s known as the keto flu, which could cause constipation headache, fatigue, irritability, cramps, and other symptoms. Don’t fret, though: Many of these symptoms are short term and should last only a few days to weeks. Make sure to drink plenty of water to help your body cope with these symptoms. And call your doctor if symptoms are prolonged.
6. Because Keto Severely Limits Carbs, You May Develop Nutrient Deficiencies
When carbohydrate intake is low, fiber consumption tends to be low, too. “This doesn’t come as a surprise when you consider fruits, whole grains, and starchy vegetables are decreased in your diet,”
Inadequate intake of potassium is likely when the consumption of fruits and starchy vegetables are decreased (a mineral important for both electrolyte balance and blood pressure control)
7. As Your Body Adjusts to Ketosis, You’ll Probably Have Bad Breath
Considered a symptom of the keto flu, your breath on this diet often smells fruity at first. This is because acetone is a by-product of ketosis and is eliminated mostly through the lungs and the breath, according to a study in the journal International Journal of Environmental Research and Public Health in February 2014. Acetone is a type of ketone known for having a fruity aroma in smaller concentrations. “It’s hard to say exactly how long it will last as it depends on the person, but it’s common for someone to experience this side effect for a few weeks,”
8. Keto Could Cause Your Blood Sodium to Dip
“When you start the keto diet, you lose sodium and other electrolytes in the urine due to reductions in insulin,” says Yawitz. “This is a major contributor to symptoms of keto flu.” So it’s important to replenish sodium through the diet, especially if you exercise or sweat a lot. “This can help ward off more serious side effects that are seen with long-term sodium deficiencies,” says Nik. These include lethargy and confusion.
9. Keto May Lead to High Cholesterol and an Increased Risk for Heart Disease
The ketogenic diet doesn’t put a cap on saturated fats or even trans fats. The latter are fats you should always avoid. Read ingredient labels and avoid any food with partially hydrogenated oils, aka trans fats. These fats heighten your LDL (bad ) cholesterol levels and lower your HDL (good)cholesterol levels. They also raise your risk of heart disease and stroke, according to the American Heart Association.
“Certainly, the quality of fat counts,” says Nik “There’s a big difference nutritionally between bacon and almonds. As much as possible, people set on the keto diet should emphasize plant-based, unsaturated fats like nuts, seeds, olive oil, and avocado, which have even been shown to protect the heart.” If you have high cholesterol or other risk factors for heart disease, you should speak with your doctor before beginning the keto diet. This is because the diet may — but doesn’t have to — include large amounts of saturated fat. Some studies have shown increases in cholesterol and triglycerides in people following the diet, while other research reveals that the keto diet may actually decrease heart disease risk as well as saturated fat intake.
10. What Everyone Should Do Before They Attempt the Keto Diet
The bottom line? If you’re thinking about trying the ketogenic diet, run it by your doctor first — regardless of any preexisting health conditions. And consult a registered dietitian nutritionist professional who can work with you to create a meal plan you can stick to. People with kidney disease or a history of disordered eating should avoid the diet, and people with type 1 diabetes may want to avoid it, as well. If you have risk factors for heart disease, you’ll want to speak with your doctor before considering the diet.
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