An interventional study of Early TRF and late TRF in Obesity, sponsored by University of Thessaly. Not yet recruiting at 1 site in Greece. Open to participants aged 12 Years to 18 Years. Per ClinicalTrials.gov, last updated 2026-08-12.
Sponsored by University of Thessaly · Not applicable, Interventional, and Treatment
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..
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's planned enrollment of 120 is above the median of 67 across 9,006 interventional studies indexed under Obesity.
Browse Obesity studies →University of Thessaly is the lead sponsor of 195 studies on the registry; 44 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion criteria are:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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
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
20% calorie deficit based on each participant's estimated total energy expenditure (TEE) with no restrictions in feeding time.
Other: Control
16 hour intermittent fasting mediterranean diet 80% of daily energy expenditure and meals are at 10:00 - 14:00 - 18:00
16 hour intermittent fasting mediterranean diet 80% of daily energy expenditure and meals are at 14:00 - 18:00 - 22:00
No intervention
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.
Time frame: Baseline, week 4, week 8 and week 12
Fat Mass (kg)
Fat mass (kg) will be measured using a calibrated bioelectrical impedance analysis device (TANITA BC-545N) under standardized conditions at baseline, week 4, week 8, and at the end of the study (week 12). The standardized measurement procedures are described in Supplementary File 4.
Time frame: Baseline, week 4, week 8 and week 12
FFM
Free Fat mass (kg) will be measured using a calibrated bioelectrical impedance analysis device (TANITA BC-545N) under standardized conditions at baseline, week 4, week 8, and at the end of the study (week 12). The standardized measurement procedures are described in Supplementary File 4.
Time frame: Baseline, week 4, week 8 and week 12
Waist Circumference (WC) (cm)
WC will be measured using a non-elastic measuring tape according to standardized protocols. The standardized measurement procedures are described in Supplementary File 4.
Time frame: Baseline, week 4, week 8 and week 12
Waist-to-Hip Ratio (WHR)
Waist-to-hip ratio (WHR) will be calculated by dividing waist circumference (cm) by hip circumference (cm). The standardized measurement procedures are described in Supplementary File 4.
Time frame: Baseline, week 4, week 8 and week 12.
HandGrip Strength (HS)
Handgrip strength (HS) will be assessed using a calibrated hand dynamometer (Jamar J00105).
Time frame: Baseline, week 4, week 8 and week 12.
Continuous Glucose Monitoring System data
Continuous glucose monitoring (CGM) devices (MENARINI GLUCOMEN iCAN) will be used to collect real-time interstitial glucose data during the first and last 14 days of the study. Participants will receive standardized instructions on device use and wear, by an expert clinician (Dr. Maria Papagianni, trial supervisor). CGM-derived metrics will include mean glucose levels, time in range (TIR), time below range (TBR) and time above range (TAR). Data will be downloaded using manufacturer-approved software and analyzed according to standardized procedures.
Time frame: Baseline to week 2 and week 10 to week 12
Chronotype
Chronotype will be assessed using the Greek version of the reduced rMEQ.
Time frame: Baseline and week 12
Physical activity levels
Physical activity levels will be evaluated with the greek version of the International Physical Activity Questionnaire (IPAQgr).
Time frame: Baseline and at week 12
Quality of Life (QoL)
Quality of life will be assessed using the Greek version of the Pediatric Quality of Life Inventory 4.0 (PedsQL 4.0 greek for Greece)
Time frame: Baseline and at week 12
Plan to share: Undecided
This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.