Intermittent calorie restriction offers only modest advantages over a low-carbohydrate, high-fat (LCHF) diet for treating nonalcoholic fatty liver disease (NAFLD), researchers say.
The intermittent diet offers more benefit for liver stiffness and LDL cholesterol, and might be easier to maintain, said Magnus Holmer, MD, head of the hepatology unit at the Karolinska Institute in Stockholm.
But the intermittent diet also has drawbacks and the differences between the two were slight, he said in an interview.
“They were more or less identically effective in reducing liver steatosis in NAFLD and also reducing body weight,” he said. “And from this, we can say that the composition of macronutrients such as fat or sugar seems to be less important than how many calories you eat.”
Dr. Holmer and colleagues presented their findings at the meeting sponsored by the European Association for the Study of the Liver and published them in JHEP Reports
While previous studies have shown that dieting can effectively treat NAFLD, researchers have debated whether popular LCHF diets might cause more harm than good.
At the same time, intermittent-calorie restriction diets have also been gaining in popularity, particularly the 5:2 diet in which participants eat normally for 5 days a week and restrict their calories the other 2 days.
How do the two diets compare?
To see if one was more effective than the other, the researchers recruited 74 people with NAFLD. They diagnosed the patients either by radiologic assessment or a combination of controlled attenuation parameter (CAP) greater than 280 dB/m and obesity, or a CAP greater than 280 dB/m, elevated ALT, and overweight. Sixteen of the patients were being treated with statins.
The researchers randomly assigned 25 people to an LCHF diet, 25 to a 5:2 diet, and 24 to standard care. The groups were similar in diet, age, body mass index, liver stiffness, and most other criteria at baseline, although there were more women in the standard-care group.
At the start of the study, the participants in the standard-care group consulted with a hepatologist who advised them to avoid sweets and saturated fats, eat three meals a day, and avoid large portions.
The researchers asked women in the 5:2 diet to eat up to 500 kcal/day each of 2 days per week and up to 2,000 kcal/day each of the other 5 days. They asked men in the group to eat up to 600 kcal/day each of 2 days per week and up to 2,400 kcal/day the other 5 days.
They provided all the 5:2 participants with recipes that followed the Nordic Nutrition Recommendations, an adaptation of the Mediterranean diet that emphasizes foods traditional in Nordic countries, particularly grains such as whole-grain rye, oats, and barley; fruits such as apples, pears, berries, and plums; root vegetables, cabbages, onions, peas, beans, fish, boiled potatoes, and dairy products; and the use of rapeseed (canola) oil. The calories provided in the recipes were composed of 45%-60% carbohydrates, 25% fat, and 10%-20% protein.
The researchers asked women in the LCHF diet to eat an average of 1,600 kcal/day and men to eat an average of 1,900 kcal/day. All the participants used recipes based on meat, fish, eggs, low-carbohydrate vegetables, and dairy fat. Participants avoided sugar, bread, pasta, rice, pies, potatoes, and fruit. The calories in the recipes were composed of 5%-10% carbohydrates, 50%-80% fat, and 15%-40% protein.
All the participants reported what they ate over the previous 3 days, both at the start of the study and after 12 weeks. Participants in the 5:2 and LCHF groups also received follow-up calls to report their past 24 hours of eating at 2, 4, 8, and 12 weeks, and also at week 6, when they visited a dietitian.
In addition, the researchers measured the participants’ linoleic acid and alpha-linolenic acid intake to verify that the participants’ diets were different among the groups.
After 12 weeks, all three groups lost a significant amount of liver fat, but the LCHF and 5:2 groups lost more than the standard care group. Liver stiffness decreased significantly in the 5:2 and standard care groups, but not in the LCHF group.
The differences in steatosis change between the standard care and LCHF groups was statistically significant (P = .001), as it was between the standard care and 5:2 groups (P = .029). The differences between the LCHF and 5:2 groups were not statistically significant for weight or steatosis, but they were statistically significant for liver stiffness.
In addition, the 5:2 group significantly reduced total and LDL cholesterol, while the standard care group did not. In the LCHF group, levels of LDL cholesterol, HDL cholesterol, and total cholesterol all increased.
The long-term implications of the cholesterol findings are unclear, Dr. Holmer said. He hopes to follow up on these patients after 18-24 months. But the initial cholesterol findings are perhaps enough to constitute a red flag for anyone with a history of cardiovascular disease.