A landmark study presented by US researchers has shown for the first time the long-term risks associated with low carbohydrate and high fat (LCHF) or ketogenic-like diets, while also filling a crucial information gap on why such measures are more harmful than good.
Many people resort to such diets to lose weight quickly.
The analysis based on a 12-year follow up showed that those on an LCHF diet have increased levels of low density lipoprotein (LDL) or bad cholesterol, along with a twofold heightened risk of cardiovascular events such as heart attacks and strokes.
For the observational analysis, 305 participants who got no more than 25 percent of total daily calories from carbohydrates and more than 45 percent from fat, were compared with 1,220 individuals who consumed a standard diet.
After an average of 11.8 years, researchers found that participants following the LCHF diet had higher levels of bad cholesterol than those on the standard diet.
Also, more than 9.8 percent of the participants in the keto-like diet group suffered atherosclerotic cardiovascular events such as heart attacks, strokes and kidney diseases, as compared to 4.3 percent from the standard-diet group.
The results were presented at the annual American College of Cardiology Conference on March 5.
“This is a significant study because it presents the first evidence for the long-term risks associated with low carb, high fat diets in such a methodical way,” R Hemalatha, director of the Indian Council of Medical Research-National Institute of Nutrition, told Moneycontrol.
“These findings are based on comparing people on a normal diet with those on a keto-like diet; so it's obvious that the long-term impact of the proper keto diet can be worse.”
What is the keto diet?
People on a keto diet consume 70-80 percent of their daily calories from fat, 5-10 percent calories from carbohydrates, and 10-20 percent of their calories from proteins.
Dietary guidelines, on the other hand, suggest that for healthy people, carbohydrates should make 45-65 percent of the total daily calories.
The premise of a keto diet is that not eating carbs will make the body depend on burning fats for fuel, pointed out senior clinician and medical researcher Rajeev Jayadevan, but it involves eating large amounts of fat from oils, nuts and meat.
Short-term gains, big harm?
Jayadevan pointed out that a keto diet can reduce weight in the short term – for example, if a professional model wants to lose some weight. But most people would gain that weight back in a year or two.
“This already raised questions about the actual health benefits of such an intervention,” he said. “Any benefit from body weight manipulation is only achieved long term.”
Prior to the latest study, while it was known that keto diets raised bad cholesterol levels, what was not established was whether this would translate into heart disease down the line, as that would take several years to follow up.
“This current study, with a 12-year follow up, shows heart disease was more among those who followed a keto diet and although it is impossible to know how long the diet was followed in such studies, it fills a crucial knowledge gap,” Jayadevan said.
Hemalatha stressed that while fancy diets may look appealing to some people for the quick, short-term results like weight loss, in the long term, a healthy and balanced diet with exercise goes a long way, as proven by the latest study.