One of the comorbidities of obesity is nonalcoholic fatty liver disease (NAFLD). L-citrulline is a non-protein amino acid that has shown positive effects on the degree of fat retention and metabolic profile in NAFLD. The objective is to assess the effect of oral L-citrulline supplementation on liver function and nonalcoholic fatty liver in adolescents with obesity. A clinical study will be carried out in 40 adolescents (15-19 years) with obesity, they will be divided into a control group that will receive a placebo and an experimental group that will receive 6 g of l-citrulline per day for eight weeks.

It is hypothesized that l-citrulline supplementation decreases liver enzymes and the degree of hepatic steatosis in adolescents with obesity. The aim of the study is to assess the effect of oral L-citrulline supplementation on liver function and nonalcoholic fatty liver in adolescents with obesity. A prospective randomized, double-blind clinical study will be carried out in 40 adolescents (15-19 years) with obesity, they will be divided into a control group that will receive a placebo (carboxymethyl cellulose) and an experimental group that will receive 6 g of pure l-citrulline per day per eight weeks. At the beginning and end of the intervention, anthropometric, biochemical and metabolic data will be evaluated, as well as tests of function and degree of hepatic steatosis.

Inclusion Criteria:

• Adolescents between 15 and 19 years old, residents of the city of León, Guanajuato, with obesity due to BMI ≥30 kg / m2 equivalent to the categorization of adults. That they are in stage 5 of Tanner scale with diagnosis of mild, moderate or severe NAFLD and / or alterations in liver enzyme levels. Not be under nutritional treatment, not be smokers, not taking multivitamins, if so, a wash time of 30 days will be given. Not be allergic to l-citrulline or watermelon. Alcohol consumption less than 21 standard drink units for men and 14 standard drink units for women per week (Standard drink: any drink with more than 14 g of pure alcohol).

Exclusion Criteria:

• Present intolerance to l-citrulline or allergy to watermelon.
• Have an adherence of less than 80 percent of the treatments.
• Present other causes of liver disease.

At the request of the researcher.

The selection of which group each adolescent will belong to will be made by randomization by simple lottery by a researcher from the Department of Medical Sciences of the University of Guanajuato who is not involved in the treatment and follow-up of the participants and will be designated to a Placebo group and to the Citrulline group. The participants and the researcher will not know which group each adolescent belongs to.