Time-Restricted Eating No Better Than Cutting Calories Alone for NAFLD

Adding time restriction to a calorie-restricted diet didn't provide any additional benefits for nonalcoholic fatty liver disease (NAFLD), the TREATY-FLD trial found.

Looking at 88 participants with obesity and NAFLD, the half that followed a calorie-restricted and time-restricted eating pattern -- only eating between 8 a.m. and 4 p.m. every day -- saw a similar reduction in intrahepatic triglyceride (IHTG) content as did those on daily calorie restriction without time constraints, reported Huijie Zhang, MD, PhD, of Southern Medical University in China, and colleagues.

After 6 months, IHTG content had dropped by 8.3% (95% CI -10.0 to -6.6) among the time-restricted dieters and 8.1% (95% CI -9.8 to -6.4) in the calorie restricted group, the researchers said in JAMA Network Open.

One-year trial results showed a similar picture, with IHTG content reductions of 6.9% (95% CI -8.8 to -5.1) and 7.9% (95% CI -9.7 to -6.2), respectively.

"These data support the importance of caloric intake restriction when adhering to a regimen of TRE [time-restricted eating] for the management of NAFLD," Zhang's group wrote, adding that "the results suggest that caloric intake restriction explained most of the beneficial effects of a TRE regimen."

While liver stiffness improved in both groups, neither diet came out superior for that measure either. The time-restricted group saw a reduction of 2.1 kPa (95% CI -2.7 to -1.6) versus 1.7 kPa (95% CI -2.3 to -1.2) in the calorie-restriction alone group at the 12-month mark.

By the end of the trial, 33% of the time-restricted group and 49% of the calorie-restricted group resolved their NAFLD to reach an IHTG content under 5% (P=0.31).

Both diets also resulted in weight loss over 12 months: 8.4 kg (18.5 lb) in the time-restricted group and 7.8 kg (17.2 lb) in the calorie-restricted-only group. This finding falls in line with a trial published in the New England Journal of Medicine last year that showed no difference in weight loss when people with obesity followed a time-restricted diet in addition to calorie restriction. In that trial, the time- and calorie-restricted group lost 8 kg (17.6 lb) after 12 months while the calorie-restricted-only dieters lost 6.3 kg (13.9 lb).

Both groups in the TREATY-FLD trial also saw significant improvements in waist circumference, body fat percentage, fat mass, lean mass, total abdominal fat, subcutaneous fat, visceral fat, and visceral to subcutaneous fat ratio. Likewise, both groups had significant reductions in liver enzymes, including serum alanine aminotransferase, aspartate aminotransferase, and γ-glutamyltransferase. Neither diet was superior on these measures.

Both diets also resulted in significant reductions in fasting plasma glucose level, HbA1c, and HOMA-IR at month 6. By the end of the trial, the time-restricted group saw a significantly greater reduction in HOMA-IR.

All participants in the trial -- which was conducted at the Nanfang Hospital in Guangzhou, China -- stuck to a diet of 1,500 to 1,800 kcal/day for men and 1,200 to 1,500 kcal/day for women, composed of 40-55% carbohydrate, 15-20% protein, and 20-30% fat. All also drank one Nutriease protein shake per day for the first 6 months along with dietary counseling throughout the study. Taking this calorie restriction one step further, the time-restricted group also had to keep their calorie intake within 8 a.m. to 4 p.m. every day, with only noncaloric beverages permitted outside of this window.

Changes in IHTG content were measured via MRI, body fat mass, and lean mass using whole-body dual x-ray; abdominal visceral fat and subcutaneous fat areas were measured by CT.

At baseline, the average age was 32 and BMI was 32.2. Some exclusion criteria included acute or chronic viral hepatitis, drug-induced liver disease, autoimmune hepatitis, diabetes, serious liver dysfunction, and chronic kidney disease. A total of 92% of participants completed the 6-month intervention, and 84% completed the full year trial.

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