Should You Try the Ketogenic Diet? Pros and Cons

Interest in the Ketogenic Diet Grows for Weight Loss and Type 2 Diabetes.

Such is the title of a new 2018 article in the Journal of the American Medical Association (JAMA). Researchers are going to follow the progress of 25 overweight and obese adults as they are randomly assigned to one of three diets: a low-fat, high-carbohydrate diet that’s either high or low in added sugars, and a high-fat ketogenic diet.

Why the interest in the ketogenic diet? A recent meta-analysis of 13 randomized controlled trials suggested that ketogenic diets, more than low-fat diets, helped people:

  • lose more weight
  • keep more of it off
  • decrease hunger

The ketogenic diet may also have less of a negative effect on metabolism than other diets. In one study, for example, metabolism slowed by more than 400 kcal/day on a low-fat diet, but there was no significant decline in the ketogenic diet.

Could this be the diet that might work for you? We looked into the pros and cons to help you decide.

What is the Ketogenic Diet?

This is the diet that’s been touted by celebrities like Kourtney Kardashian and Tim Tebow, and it’s very popular right now. In essence, it is a very low-carbohydrate, high-fat diet that includes moderate amounts of protein. The goal of the diet is to kick the body into a state of “ketosis.” Thus, the name “ketogenic” or “keto.”

Ketosis naturally occurs when the body is short on glucose. The body takes carbohydrate foods like fruits, milk, yogurt, bread, and pasta and turns them into glucose for energy. It then uses that energy to fuel your daily activities. As long as there is plenty of glucose available, any fat is stored away for potential future emergencies.

If there isn’t enough glucose available, though, the body turns to fat instead. When this happens, the body produces “ketones” as by-products of that fat-burning process and burns them for energy. At that point, you are in a state of ketosis.

Scientists believe our ancestors developed this ability to use ketones for energy because they had frequent periods of time when food wasn’t immediately available. It’s a survival process that helps people get through periods of the low food supply.

In today’s world, though, we typically have food available at all times, yet we’ve retained this ability to use fat for fuel when we need to. If we limit the carbohydrates we’re consuming, we can encourage the process of ketosis in our own bodies, and inspire our systems to turn to fat, rather than glucose, and hopefully, for fuel, which can help with weight loss.

On a typical ketogenic diet, one would avoid carbohydrates, which are found in grains, sugar, fruits, tubers (potatoes and yams), and legumes, and eat more meat, fish, eggs, leafy greens, high-fat dairy, above-ground vegetables, nuts and seeds, avocados and berries, and other fats like coconut oil and salad dressings.

What are the Positive Things About the Ketogenic Diet?

In a ketogenic diet, you cut way back on carbohydrates, and make up the difference with fats. In fact, about 75 percent of the calories you consume come from fat, with about 20 percent from proteins, and 5 percent from carbohydrates. By following this diet, your body will go into a state of ketosis after about three to four days.

Weight Loss

The main positive outcome of this diet is weight loss. In one study of 17 obese men, participants lost more weight on a four-week ketogenic diet than on a four-week medium-carbohydrate diet, and they also experienced less hunger. The researchers noted that in the short-term, high-protein ketogenic diets “reduce hunger and lower food intake significantly more than do high-protein, medium-carbohydrate nonketogenic diets.”

As noted at the beginning of this article, in an analysis of 13 studies comparing a ketogenic diet with a low-fat diet, individuals on the ketogenic diet achieved greater weight loss than those on the low-fat diet, leading researchers to theorize that it may be “an alternative tool against obesity.”

In yet another study, researchers followed the effects of a longer, 24-week ketogenic diet in 83 obese patients who also had high blood sugar and cholesterol levels. They found that the patients’ weight and body mass index (BMI) decreased significantly. In addition, their total cholesterol levels also decreased and their HDL “good” cholesterol levels increased. Researchers noted that the diet didn’t produce any significant side effects.

Lowered Blood Sugar and Cholesterol

As shown in the above study, it seems the ketogenic diet may have some other benefits as well, like reducing blood sugar levels and improving metabolic syndrome (a cluster of symptoms including high blood pressure and triglycerides that can lead to heart disease). In a small 2005 study, for example, researchers found that following a ketogenic diet for 14 days helped participants not only decrease their calorie intake and lose weight, but also lowered their blood sugar, triglyceride, and cholesterol levels.

Reduced Dangerous Belly Fat

Other studies have suggested that the ketogenic diet may help reduce dangerous belly fat, which has been linked to an increased risk of cardiovascular disease. Participants on the diet experienced greater overall weight loss than those on a low-fat diet, but also significantly reduced so-called “trunk fat” or belly fat, at a greater rate than what would have been expected from the weight loss alone.

More Efficient Exercise

We have other research suggesting that when you’re on a ketogenic diet, you’ll be able to burn more fats when you exercise. It makes sense since you have less glucose available for energy, but researchers have confirmed it in studies. In 2016, for example, they found that compared to marathon runners on a high-carbohydrate diet, those consuming a ketogenic diet had “extraordinarily high rates of fat oxidation,” with no significant differences in recovery rates.

Higher Resting Fat-Burning Rate

How much fat do you burn when you’re just resting? Studies have found that you may burn more when you’re on a ketogenic diet. They divided 40 overweight people into two groups and fed one a low-calorie Mediterranean diet, and the other a ketogenic Mediterranean diet. Both diets led to weight loss, but the reduction was greater on the ketogenic diet. In addition, the ketogenic diet led to an increased use of fat at rest. Better yet, the results lasted for up to 20 days after the participants went back to their normal diets.

Reduced Seizures

The ketogenic diet has also been used for decades to help treat epilepsy in people who don’t respond to epileptic medications, as it can help reduce the frequency of seizures. Researchers are also looking into whether the diet might help improve other related disorders, like Parkinson’s disease and multiple sclerosis.

Warnings and Risks of the Ketogenic Diet

All these results sound great, right? It would seem like everyone should try the ketogenic diet to lose weight and enjoy better health. There are potential negative outcomes of a ketogenic diet, however, that you need to be aware of.

Ketoacidosis

Ketones are naturally acidic, and if you build up too many in your system, your blood could become too acidic, which is a dangerous state. Diabetics are already at risk for this outcome, which can occur when they don’t get enough insulin or aren’t drinking enough fluids. Symptoms include extreme thirst, frequent urination, nausea and vomiting, stomach pain, fatigue, shortness of breath, and a fruity-smelling breath.

That means this diet could be dangerous for those with diabetes. People without diabetes can suffer from ketoacidosis when consuming a low-carbohydrate diet, too, though it is a more rare occurrence. In 2006, researchers reported on a case study of a 51-year-old woman who maintained a ketogenic diet and ended up in the hospital four times until doctors encouraged her to eat carbohydrates again, after which she recovered.

Keeping ketones under control is one thing those on a ketogenic diet have to be careful about. There is a line between a “healthy” state of ketosis and a dangerous state of ketoacidosis. Usually, in ketoacidosis, the level of ketones is 3-5 times higher than in ketosis. That’s why the diet allows for a small amount of carbohydrates, to keep ketone production from getting out of hand.

People on the ketogenic diet are also wise to regularly test their ketone levels either with a blood ketone meter or urine test strips, though the strips can become less accurate the longer you’re on the diet. There are also breath meters that can measure the ketones in the body.

Digestive Ailments

Since the diet includes a lot of fat and few grains, it tends to be a low-fiber diet, which can cause digestive problems, most commonly, constipation, though bloating and diarrhea may result, too. This lack of fiber may also have other long-term health consequences, but we don’t have enough long-term studies to be sure. Meanwhile, do your best to choose high-fiber foods on your diet, and consider taking a fiber supplement.

Risk of Eating Unhealthy Fats

Though most advocates of the ketogenic diet recommend consuming healthy fats, some people end up eating too much butter, fatty meats, and cheese, which may cause other long-term health issues, including heart disease. Those trying the diet should be sure to choose healthy fats like those in nuts, avocados, fatty fish, olive oil, etc.

Fatigue, Headaches, Brain Fog

Though the ketogenic diet can eventually lead to more consistent energy levels, when people first go on it, they often experience fatigue because of the drop in blood sugar. Usually, this side effect passes within a few days. Other possible short-term side effects may include headaches, decreased exercise performance, moodiness, brain fog (or fuzzy thinking), bad breath, muscle weakness, and insomnia. Some dieters call this adjustment period the “keto flu.”

Nutrient Deficiencies

Because the diet is quite restrictive, there is a risk of nutrient deficiencies. That’s why most ketogenic advocates recommend supplements while you’re on the diet (starting with a quality multivitamin/mineral supplement). Check with your dietician to find which ones are best for you.

Rebound Weight Gain

Most people don’t stay on the ketogenic diet long-term, because it’s so restrictive. When you go back to your normal eating habits, you may regain some or all of the weight you lost. If you’re not planning on staying on the diet long-term, you have to be really careful of this, as you could end up in a see-saw process of losing and regaining the weight, which has shown in most studies to be more dangerous than maintaining a single weight.

We still need more research on maintaining weight loss following a ketogenic diet. Some research shows that cycles of brief ketogenic diets followed by longer periods of the standard Mediterranean diet can help maintain weight loss. You can also ease yourself back into your standard diet, increasing your carb intake bit-by-bit so you can keep your intake at a moderate level.

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