Abstract and Introduction
Different dietary regimens for weight loss have developed over the years. Since the most evidenced treatment for non-alcoholic fatty liver disease (NAFLD) is weight reduction, it is not surprising that more diets targeting obesity are also utilized for NAFLD treatment. However, beyond the desired weight loss effects, one should not ignore the dietary composition of each diet, which may not necessarily be healthy or safe over the long term for hepatic and extrahepatic outcomes, especially cardiometabolic outcomes. Some of these diets are rich in saturated fat and red meat, are very strict, and require close medical supervision. Some may also be very difficult to adhere to for long periods, thus reducing the patient's motivation. The evidence for a direct benefit to NAFLD by restrictive diets such as very-low-carb, ketogenic, very-low-calorie diets, and intermittent fasting is scarce, and the long-term safety has not been tested. Nowadays, the approach is that the diet should be tailored to the patient's cultural and personal preferences. There is strong evidence for the independent protective association of NAFLD with a diet based on healthy eating patterns of minimally-processed foods, low in sugar and saturated fat, high in polyphenols, and healthy types of fats. This leads to the conclusion that a Mediterranean diet should serve as a basis that can be restructured into other kinds of diets. This review will elaborate on the different diets and their role in NAFLD. It will provide a practical guide to tailor the diet to the patients without compromising its composition and safety.
The prevalence of obesity is increasing worldwide, with a third of all adults currently defined as people with overweight or obesity. Higher levels of adiposity are associated with several co-morbidities, including hypertension, stroke, cardiovascular disease (CVD), and type-2 diabetes mellitus (T2DM),[2,3] as well as with all-cause mortality. Obesity-associated morbidities are strongly associated with fat accumulation in body pools that are not physiological storage areas (ectopic fat), such as intra-abdominal organs, including the liver, pancreas, heart, kidney, and muscle. Non-Alcoholic Fatty Liver Disease (NAFLD) is the hepatic manifestation of obesity and the metabolic syndrome. NAFLD can progress to non-alcoholic steatohepatitis (NASH), liver fibrosis and cirrhosis, and liver cancer and is independently associated with increased risk for T2DM and CVD. NAFLD is the most common liver disease worldwide, affecting as many as a quarter of the global adult population. NAFLD prevalence is very high in people with obesity, who have a 3.5-fold increased risk of developing NAFLD compared to those with normal weight. Similarly, the prevalence of NAFLD among T2DM patients is 60%, more than two-fold higher than the general population.
Current recommendations for the treatment of NAFLD and visceral fat suggest at least 5% weight loss and a greater reduction of 10% to regress fibrosis in most patients. However, improvements in NASH and fibrosis can also be seen with moderate weight reduction. Unfortunately, weight loss also reduces lean mass,[10,11] and losing weight and maintaining weight loss in the long term is a complex process and remains a major public health challenge.
Currently, there is no effective drug therapy for NAFLD, although several compounds are under development. Therefore, lifestyle modifications are considered the first-line treatment. The approach nowadays is that the type of diet should be tailored to the patient's cultural and personal preferences. Patients are exposed to various diet regimens (e.g., on the media and social networks) and wish to try them or have gained experience knowing which diet works for them. In this review, we will illustrate the efficacy and applicability of five main common dietary strategies for the treatment of NAFLD: low-fat diet, Mediterranean diet, low-carbohydrate (carb) diet, ketogenic (keto) diet, and time-restricted eating (TRE).
Liver International. 2022;42(8):1731-1750. © 2022 Blackwell Publishing