A high-fat and low carbohydrate diet has more health benefits for people with obesity compared to other weight loss methods such as a Mediterranean diet or a low-fat diet, research suggests.
About 30 per cent of adults in the UK are obese and an estimated 6.3 million people live with non-diabetic hyperglycemia, more commonly known as prediabetes.
The Mediterranean diet, which is rich in fruit, veg, pulses and oily fish, is often recommended as a healthy option for people with prediabetes to promote weight loss.
But US researchers found that after eating a Keto diet for four to five months, about half of study participants with obesity and prediabetes no longer met the criteria for prediabetes.
“We know weight loss can improve metabolic health in people who are obese,” Samuel Klein, the study’s corresponding author at Washington University School of Medicine in St Louis, Missouri said.
“Our data suggest that if you have high liver fat content and prediabetes, reducing carbohydrate intake can have important therapeutic effects on metabolism beyond just weight loss alone,” he added.
For the study, published in the journal Cell Metabolism, researchers compared three popular diets – Keto, Mediterranean and plant-based.
All the diets have different nutrient compositions. a Mediterranean diet contains mostly plant-based foods, such as vegetables, olive oil, and nuts, with moderate amounts of fish and dairy, while a Ketogenic diet can include foods high in saturated fat, including animal products.
The Keto diet is a low-carbohydrate diet and uses energy from protein and fat, while a low-fat diet can source as much as 70 per cent of its energy from carbohydrates.
The study involved 42 people who had obesity, prediabetes, and fatty liver disease.
The researchers randomly assigned them to one of three diet groups: a ketogenic diet, a Mediterranean diet, or a low-fat, plant-forward diet. The participants received all of their food from the research team and met weekly with a dietitian to help them adhere to their assigned diets.
The team tailored each participant’s calorie intake so that everyone lost about 10 per cent of their body weight, which took about four to five months.
By the end of the trial, all three diets led to fat loss and each participant also became more sensitive to insulin, improving their ability to regulate blood sugar.
But the biggest improvements were seen on the Keto diet. Liver fat decreased by an average of 67 per cent in the ketogenic group, compared with 45 percent in both the Mediterranean and the plant-forward groups.
The ketogenic diet group also had the largest increase in glucagon, which is a hormone that promotes fat loss in the liver and experienced the greatest reduction in blood insulin levels, which also reduces fat content in the liver, compared to the other two groups.
“The most surprising finding was that participants in the ketogenic diet group didn’t experience an increase in blood fat or cholesterol levels despite consuming the most fat,” Max Petersen, the study’s first author at Washington University School of Medicine said.
Following the weight-loss intervention, about 50 per cent of participants in the ketogenic group no longer met the criteria for prediabetes, compared with 29 per cent in the Mediterranean group and 7 per cent in the plant-forward group.
But experts have questioned if a Keto diet is sustainable for long-term weight loss.
“Larger and longer-term trials, ideally with at least one year of follow-up, are needed to establish the comparative benefits and risks of these dietary approaches,” Naveed Sattar, Professor of Cardiometabolic Medicine at University of Glasgow, who was not involved in the study said.
“An important practical consideration is whether people can sustain a very low-carbohydrate ketogenic diet over the long term.”
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