Obesity is now recognized as a serious public health problem. It is known that obesity seen in adolescence is largely carried over to adulthood. Therefore, its treatment is important both in terms of protecting current health and preventing diseases in adulthood. Reducing energy intake plays an important role in the treatment of obesity. However, long-term adherence and effectiveness to energy restriction appear to be limited. Therefore, the need for interventions that are "effective in body weight loss" and "accessible, simple and lifestyle modification to increase dietary compliance" is clear. Time-restricted feeding is a specialized intermittent fasting protocol that includes consistent fasting and eating periods over a 24-hour cycle by supporting circadian rhythms. Especially in the adult population, positive effects of time-restricted feeding such as weight loss and blood glucose regulation are observed. However, there are limited data on this subject for adolescents. Today, the Mediterranean diet, which is one of the nutrition models that supports health, is a beneficial nutritional model that reduces body weight and obesity-related comorbidities by limiting total energy intake. However, no study has been found in the literature in which the effectiveness of time-restricted nutrition, which is a new and promising approach, and the Mediterranean diet, which is a sustainable diet model, are evaluated together. Therefore, in this study, it was aimed to evaluate the effects of planned time-restricted nutrition compatible with circadian rhythm and energy-restricted feeding planned according to the Mediterranean diet model on body composition and various metabolic parameters in obese adolescents. 60 obese adolescents aged 12-18 years will be included in this randomized controlled and parallel design study. Participants will be randomized to one of two treatment groups for a 12-week intervention. The time-restricted feeding group will form the intervention group of the study, and the energy-restricted feeding group will form the control group. Anthropometric measurements of the participants at the beginning and end of the study will be taken, and various biochemical parameters will be evaluated with the body composition and blood samples to be taken. As a result of the study, it is expected to determine the effectiveness of time-restricted feeding compared to energy-restricted feeding in terms of dietary compliance, body composition and biochemical changes.

Inclusion Criteria:

• Adolescents aged 12-18 with puberty stage:5
• Obese adolescents with a metabolic disorder (such as fatty liver, insulin resistance, prediabetes, dyslipidemia) (BMI≥95th percentile for age)
• Those who have a stable body weight for 3 months before the start of the study (current weight gain or loss <4 kg)
• Those who own and can use a Smartphone with Apple iOS or Android operating system
• Those who speak, read and understand Turkish

Exclusion Criteria:

• Those with any endocrine disorder, metabolic, chronic or major psychiatric disease other than obesity, insulin resistance, dyslipidemia, prediabetes, fatty liver
• Polycystic ovary syndrome (PCOS)
• Those with physical or mental disabilities
• Those with allergies, intolerances or eating disorders
• Those who smoke and drink alcohol
• Use of drugs that may affect study results, circadian rhythms or metabolism (such as antidiabetics, steroids, beta blockers, adrenergic stimulating agents, laxatives, etc.)