Is the ketogenic diet more effective for people with metabolic syndrome than a standard American diet with exercise?
Researchers from Bethel University in Minnesota think so.
But dietitians say it may not be that simple.
The researchers set out to discover if a sustained, controlled ketogenic diet would reduce the impact of metabolic syndrome as well as decrease the weight, body mass index (BMI), and body fat mass of study participants.
They brought together a group of 30 adults who had been diagnosed with metabolic syndrome, a cluster of conditions that occur at the same time.
People with metabolic syndrome are at an increased risk of heart attack and stroke.
The researchers randomly split participants into three groups.
One group followed a sustained ketogenic diet with no exercise.
Another undertook a standard U.S. diet with no exercise.
The third followed a standard U.S. diet with 30 minutes of exercise for three to five days per week.
At the end of the 10-week period, those in the ketogenic group saw the best results for reduction of weight, body fat percentage, and BMI.
“All variables for the ketogenic group outperformed those of the exercise and non-exercise groups, with five of the seven demonstrating statistical significance,” the authors wrote.
The ketogenic diet (sometimes called “keto”) is a low-carb, high-fat diet that involves drastically reducing the amount of carbohydrates you eat and replacing them with fats.
The body responds to this reduction by going into a state called ketosis.
“Carbohydrates are the main fuel our body was designed to use and the only fuel that the brain and heart muscles use. When we don’t eat enough carbohydrates, the body looks for other forms of energy to satisfy that role. Without carbs, our insulin levels drop and fat is released from our cells. The liver turns the fat into ketones, our body’s second choice for energy,” Lauri Wright, PhD, an assistant professor in public health at the University of South Florida, told Healthline.
The keto diet has been used in medicine in conjunction with other therapies to help children with epilepsy. This is done under supervised conditions with a medical professional.
Whether the diet can be used safely for weight loss, however, remains to be seen.
“The ketogenic diet appears to be safe in the short term (like this 10-week study). However, we don’t have much evidence that it’s safe in the long term, or sustainable,” Jennifer McDaniel, a registered dietician and spokesperson for the Academy of Nutrition and Dietetics, told Healthline.
Wright notes there’s a concern a long-term keto diet could be damaging.
“Because ketone excretion can increase the pressure in the kidneys, there is a concern about the effects on renal function. There is also a concern about loss of muscle mass that results from relying on ketones for fuel,” she said.
Although the results of the study found that participants in the ketogenic group had the best results in terms of weight loss, Wright is quick to point out that this doesn’t necessarily mean this is a more effective weight loss method for this group.
“The greater weight loss resulted from loss of water rather than body fat. Studies show us that the water weight comes back quickly, and often people experience a rebound weight gain in response to the deprivation from the diet and changes in the metabolic rate. It is body fat that increases health issues,” she said.
According to a 2015 study, approximately 35 percent of all U.S. adults have metabolic syndrome. That increases to 50 percent for those 60 and over.
One of the most important steps to preventing and treating metabolic syndrome is weight loss.
A healthy diet combined with exercise helps with this. Experts say that metabolic syndrome occurs less often in those who are regularly engaging in some form of physical activity.
The American Academy of Nutrition and Dietetics recommends a heart-healthy diet for those with metabolic syndrome, including a high intake of fruits and vegetables, low-fat or fat-free diary, whole grains, seafood, and moderate amounts of lean meat, poultry, and oils.
McDaniel says a reduction in carbohydrates is helpful for weight loss, but it doesn’t need to be as extreme as in the ketogenic group in the Bethel study.
“It appears low-carb diets, in general, tend to be more effective for weight loss compared to the standard American diet. Low-carb diets can help people lose weight, but they just don’t have to be this extreme. We have strong evidence that high-quality carbs that contain fiber and resistant starches like vegetables, beans, and whole grains support weight loss and reduce risk factors of the metabolic syndrome,” she said.
Dana Hunnes, PhD, a senior dietitian at the Ronald Reagan UCLA Medical Center in Los Angeles, argues that although the study participants in the ketogenic group achieved seemingly better results, this could simply be due to the inadequacies of the standard American diet.
“Almost any diet instead of the standard American diet might result in similar (perhaps attenuated) results. A standard American diet is by no means a healthy diet. It is usually 30 percent fat, often high in saturated fat, 50 percent or more carbs, typically refined carbs that are high in sugar. It is a diet that is typically high in salt and low in fiber and other beneficial nutrients,” she said.
“I’m not sure that comparing this diet (keto) to the standard American diet is really a fair analysis when they could have also compared it to other diets ‘known in the literature’ to reduce the risks for metabolic syndrome,” Hunnes added.