Comparison of the effect of a low-carbohydrate diet with restricted calories and a standard diet with restricted calories on the levels of liver enzymes, insulin resistance and body composition in obese or overweight children and adolescents with non-alcoholic fatty liver disease.

Determining the effect of a low-carbohydrate, calorie-restricted diet and a standard calorie-restricted diet on liver enzyme levels, insulin resistance, and body composition (including height, weight, body fat mass, body fat-free mass, and body water) in obese or overweight children and adolescents suffering from non-alcoholic fatty liver disease

A double-arm, randomized clinical trial, with sample size of 60 people (30 people in each group)

Participants are selected from the number of people who refer to Tehran Children's Medical Center Hospital. If they are eligible, they will enter the study. In the case of blinding, the anthropometric evaluations and the measurement of biochemical factors in the blood samples of the participants will be done by persons who are not aware of the group of each participant.

Eligible participants in this study are children and adolescents aged 5 to 18 years with NAFLD and obesity or overweight. ⋆ Age 5 to 18 years ⋆ Obesity or overweight ⋆ NAFLD based on serum ALT levels Non-entry criteria: ⋆ suffering from other liver diseases ⋆ Suffering from autoimmune diseases ⋆ suffering from hereditary metabolic diseases ⋆ History of receiving intravenous nutrition ⋆ History of using steatogenic drugs ⋆ Alcohol consumption ⋆ Pregnancy

Intervention group: the group receiving a low-carbohydrate diet with limited calories Control group: the group receiving the standard calorie-restricted diet

Liver enzyme levels (ALT and AST); body composition (including height, weight, body fat mass, body fat-free mass and body water); lipid profile (TG, TC, LDL, HDL); insulin resistance (by HOMA-IR index); Fasting plasma glucose

The participants were randomly divided into two groups: a standard calorie-restricted diet and a calorie-restricted low-carbohydrate diet. A block randomization scheme is used for randomization. The randomization process as mentioned above was done online and by the sealedenvelope website at the address (https://www.sealedenvelope.com/simple-randomiser/v1/lists) and then the output of its production sequence was received in the form of an Excel file. The closed envelope method will be used to perform randomization; For this purpose, 60 envelopes are numbered from 1 to 60 and then according to the random sequence, they are written on papers and sealed inside the envelope according to the received regime. The participants were given an envelope by the relevant nutritionist in the order that they enter the study, and based on the diet in the envelope, they are divided into one of two study groups, i.e., a low-carb diet with limited calories or a standard diet with limited calories.

Anthropometric evaluations as well as measurement of biochemical factors in the participants' blood samples will be performed by persons who are not aware of each participant's group, and so-called blinding is done in the case of biochemical evaluations and anthropometry.