Chrono-Fasting in Overweight and Obese Adolescents

NCT07759414 | Not Yet Recruiting

• 2 other identifiers: UTH-DND-2026-001No Funding Number
• Study Type: interventional
• Target: 120
• Locations: 1 country
• Sites: 1

Brief Summary

Childhood and adolescent obesity represents a major global public health concern, with a steadily increasing prevalence over recent decades, accompanied by a rise in metabolic disorders among younger populations. Time-restricted feeding (TRF) has emerged as a promising dietary intervention, with preliminary evidence suggesting potential beneficial effects on body weight reduction and metabolic parameters in adolescents with overweight or obesity. Chronotype, defined as an individual's sleeping habits and daily activities, has a biological basis and is influenced by the circadian rhythm. Chronotype is shaped by behavioral and environmental factors, including sleep schedules, meal timing, and light exposure, and plays an important role in regulating physiological processes. Notably, adolescents with a late chronotype are more likely to exhibit higher body mass index (BMI), irregular eating patterns, including breakfast skipping, and potentially reduced responsiveness to weight-loss interventions. Despite the growing body of literature on TRF in adolescents, existing intervention models remain heterogeneous and do not account for chronotype as a potential modifier of treatment effectiveness. This represents an important gap in current research. Therefore, investigating the interaction between chronotype and the timing of food intake within TRF regimens is of particular interest. Additionally, comparing different intervention strategies with a control group may provide more robust evidence regarding their relative effectiveness. The aim of this randomized controlled trial is to evaluate the effectiveness of two TRF interventions combined with calorie restriction on weight loss in adolescents with overweight or obesity and a late chronotype, compared with a control group receiving calorie restriction without specific instructions regarding meal timing. The primary outcome variable is the change in body weight z-score, measured at baseline, at week 4, week 8 and at the end of the intervention (week 12). Secondary outcomes include changes in fat mass (FM), fat-free mass (FFM), waist circumference (WC), waist-to-hip ratio (WHR), handgrip strength, and behavioral outcomes, including physical activity levels (PAL), quality of life (QoL), and changes in chronotype. Intercurrent events, such as non-adherence to the intervention, will be handled using an intention-to-treat approach, including all randomized participants in the analysis. All participants will be monitored throughout the study period. Adherence to the intervention protocols will be assessed through CGM system and via 24 hour dietary recalls and monitoring of eating windows. Participants will be instructed to record daily meal timing, and adherence will be evaluated based on consistency with the prescribed time-restricted feeding schedule. Continuous glucose monitoring will be performed during the first and last 14 days of the study. All participants in the groups will be monitored. All participants will receive a phone call assessment in week 6 to ensure adherence Participation in this study may provide potential benefits, including weight loss, improved metabolic health, and increased awareness of healthy lifestyle behaviors. Additionally, this study may contribute to the development of more effective and personalized dietary interventions for adolescent obesity. Potential risks are expected to be minimal and primarily related to TRF, including temporary hunger, fatigue, or mild discomfort, particularly during the initial adaptation period, as well as mild irritation associated with CGM sensor placement. These effects are anticipated to be transient and will be carefully monitored throughout the study..

Conditions

Obesity

Keywords

chronotype; IF; TRF; TRE; Obesity; adolescents; weight management; intermittent fasting; CGM

Outcome Measures

Primary Outcomes (1)

• Weight Z score

  the change in weight's-score. Body weight will be measured using a calibrated digital scale (TANITA BC 545N) under standardized conditions at baseline, at 4 weeks, at 8 weeks and at the end of the study (12 weeks). The standardized conditions are mentioned in supplemental file No 4.

  Baseline, week 4, week 8 and week 12

Secondary Outcomes (5)

• Fat Mass (kg)

  Baseline, week 4, week 8 and week 12

• FFM

  Baseline, week 4, week 8 and week 12

• Waist Circumference (WC) (cm)

  Baseline, week 4, week 8 and week 12

• Waist-to-Hip Ratio (WHR)

  Baseline, week 4, week 8 and week 12.

• HandGrip Strength (HS)

  Baseline, week 4, week 8 and week 12.

Other Outcomes (4)

• Continuous Glucose Monitoring System data

  Baseline to week 2 and week 10 to week 12

• Chronotype

  Baseline and week 12

• Physical activity levels

  Baseline and at week 12

Study Arms (3)

eTRF

EXPERIMENTAL

Specific time of feeding: first meal at 10:00 a.m. and the last meal at 6:00 p.m. with 20% calorie deficit based on each participant's estimated total energy expenditure (TEE).

Other: Early TRF

lTRF

EXPERIMENTAL

Specific time of feeding: first meal at 2:00 p.m. and the last meal at 10:00 p.m. with 20% calorie deficit based on each participant's estimated total energy expenditure (TEE).

Other: late TRF

Control

ACTIVE COMPARATOR

20% calorie deficit based on each participant's estimated total energy expenditure (TEE) with no restrictions in feeding time.

Other: Control

Interventions

Early TRF OTHER

16 hour intermittent fasting mediterranean diet 80% of daily energy expenditure and meals are at 10:00 - 14:00 - 18:00

eTRF

late TRF OTHER

16 hour intermittent fasting mediterranean diet 80% of daily energy expenditure and meals are at 14:00 - 18:00 - 22:00

lTRF

Control OTHER

No intervention

Control

Eligibility Criteria

• Age: 12 Years - 18 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• Adolescents aged 12-18 years.
• Screening for overweight/obesity, defined according to the World Health Organization (WHO) Growth Reference for School-aged Children and Adolescents (5-19 years) as a body mass index (BMI)-for-age z-score \> +1 Standard Deviation (SD)
• Late chronotype, assessed using the Morningness-Eveningness Questionnaire (rMEQ) in Greek language
• Provision of verbal assent from the participants and written informed consent from participants and their parents/guardians.

You may not qualify if:

• Early or intermediate chronotype, assessed using the rMEQ questionnaire in Greek language.
• Presence of chronic medical conditions affecting metabolism (i.e., diabetes mellitus, thyroid disorders).
• Use of medications that may influence body weight, appetite, or metabolism. (i.e. thyroxin or other thyroid medication, metformin, glpi1 analogs, estrogens, progesterone, testosterone, antidepressants)
• Diagnosed eating disorders.
• Participation in another clinical trial or structured weight loss program.

Sponsors & Collaborators

• University of Thessaly: lead

Study Sites (1)

Private Endocrine Center

Larissa, Thessaly, Greece

Location

Related Publications (3)

• Ekiz Erim S, Sert H. The relationship between chronotype and obesity: A systematic review. Chronobiol Int. 2023 Apr;40(4):529-541. doi: 10.1080/07420528.2023.2180385. Epub 2023 Feb 20.

  PMID: 36803075 BACKGROUND

• Moon S, Kang J, Kim SH, Chung HS, Kim YJ, Yu JM, Cho ST, Oh CM, Kim T. Beneficial Effects of Time-Restricted Eating on Metabolic Diseases: A Systemic Review and Meta-Analysis. Nutrients. 2020 Apr 29;12(5):1267. doi: 10.3390/nu12051267.

  PMID: 32365676 BACKGROUND

• Ribas-Latre A, Fernandez-Veledo S, Vendrell J. Time-restricted eating, the clock ticking behind the scenes. Front Pharmacol. 2024 Aug 8;15:1428601. doi: 10.3389/fphar.2024.1428601. eCollection 2024.

  PMID: 39175542 BACKGROUND

MeSH Terms

Conditions

Obesity; Intermittent Fasting

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Fasting; Feeding Behavior; Behavior

Central Study Contacts

Nikolaos Ntelis Ioannis Nikolaos I. Ntelis, PhD candidate

CONTACT

+306981955467; delidiet.gr@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator, Dietitian and Nutritionist, PhD Candidate

Model Details: three parallel groups: 2 interventional groups and 1 control group

Study Record Dates

• First Submitted: July 30, 2026
• First Posted: August 12, 2026
• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): September 1, 2028
• Study Completion (Estimated): September 1, 2029
• Last Updated: August 12, 2026

Record last verified: 2026-07

Locations

GR (1)