Effect of Meal Frequency on Diet Self-Efficacy and Perceived Stress in Women With Weight Cycling

Effect of a Diet Intervention With Different Meal Frequencies on Diet Self-Efficacy and Perceived Stress in Women With Weight Cycling: A Randomized Controlled Trial

The World Health Organization (WHO) defines obesity as abnormal or excessive fat accumulation in the body that may adversely affect health. In 2022, 1 in 8 people worldwide lived with obesity, while the adult obesity rate has more than doubled since 1990, and the adolescent obesity rate has quadrupled.

Obesity is a risk factor for noncommunicable diseases such as type 2 diabetes, hypertension, cardiovascular diseases, cancer, and sleep apnea, and is associated with an increased risk of death. The treatment of obesity-related comorbidities, along with indirect costs resulting from lost productivity and premature death, contributes to the economic burden caused by obesity. Therefore, effective management of obesity is of critical importance for improving overall health outcomes and reducing the burden on healthcare systems. It has been demonstrated that a 5% reduction in body weight in individuals diagnosed with obesity can improve health outcomes, and this value has been established as a target standard for weight loss interventions. However, while dietary interventions can achieve clinically meaningful weight loss, weight regain is common due to a combination of low adherence to dietary strategies and compensatory physiological mechanisms that influence weight regain. Consequently, individuals may find themselves in a "weight cycle," losing weight and then regaining it. Weight maintenance is defined as intentional weight loss followed by the preservation of that loss for at least six months. It has been noted that the weight cycle complicates this process.

The weight cycle defined as repeated periods of intentional weight loss followed by regain is considered a common yet poorly understood factor among obese individuals. The weight cycle is viewed as one of the major challenges in clinical obesity care. For this reason, it is emphasized that strategies aimed at preventing weight cycling or promoting weight maintenance have gained importance. Additionally, attention is drawn to psychological factors in eating behavior, with particular emphasis on the individual's self-confidence and stress levels being crucial for sustaining healthy eating behaviors.

Individuals experiencing weight cycling often face challenges with diet adherence, sustainability, and stress management. Meal frequency strategies applied to these individuals can influence not only weight loss but also diet adherence and the psychological experience of the dietary process. Given the rise in obesity and obesity-related disorders, understanding the relationship between stress, self-efficacy, and food choice in young adulthood may offer insights into preventing adverse health outcomes in later life stemming from poor dietary habits. An appropriate meal schedule can help an individual adapt better to the diet and manage the process with less stress; thereby facilitating weight maintenance success and making healthy eating a lifestyle. However, in the treatment of obesity, data regarding different meal frequency approaches in dietary interventions remain controversial.

The aim of this study is to examine the factors influencing the sustainability of the diet and the long-term maintenance of weight loss in individuals experiencing weight cycling. In this context, the effects of different meal frequencies on this process were evaluated; the study addressed not only physical outcomes but also psychological factors such as how individuals felt during the dietary process, their stress levels, and their self-confidence. Thus, the aim was to present a more comprehensive perspective by examining the relationship between meal frequency and weight management from both physiological and psychological dimensions.

Study Overview

• Status: Completed
• Conditions: Meal Frequency; Perceived Stress; Obesity & Overweight; Weight Cycling; Dietary Self-efficiacy
• Intervention / Treatment: Behavioral: 3-meal diet plan; Behavioral: A dietary intervention comprising 3 main meals and 3 snacks

Detailed Description

The study was conducted on women aged 25-55 who voluntarily applied to a dietary counseling office, met the inclusion criteria, had a BMI between 25 and 35 kg/m², and experienced weight fluctuations. In the analysis conducted to determine the sample size, the effect size was f = 0.204, the Type I error level was α = 0.05, the test power (1-β) was 0.95, and measurements were taken at 6 time points (0, 2, 4, 6, 8 Weeks and 6 months after the intervention ended), inter-measurement correlation r = 0.50, and the non-sphericity correction ε = 1. Under these conditions, the required total sample size was determined to be 41; considering the anticipated 20% participant attrition during the study, it was determined that at least 49 participants were needed, and to obtain more accurate data, it was planned to include at least 52 participants; the study was completed with a total of 59 participants. The intervention phase of the study lasted 8 weeks for each participant. During the intervention period, face-to-face interviews were conducted every 2 weeks, and all measurements within the scope of the study were repeated. Following the completion of the 8-week intervention, no further intervention or follow-up was conducted, and participants' ability to maintain their weight loss was assessed via a single follow-up measurement 6 months later. In accordance with the recommendations, a weight-loss diet was planned and implemented for each participant, reducing daily energy intake by 500-700 kcal to facilitate a weight loss of 0.5-1.0 kg per week; A weight-loss diet appropriate for the women's age and energy and nutrient requirements was planned, and two groups were formed using a simple randomization method. Group 1 followed a meal plan consisting of 3 main meals, while Group 2 followed a meal plan consisting of 3 main meals and 3 snacks. Written and verbal informed consent was obtained from all participants via the "Informed Consent Form." At the beginning of our study, a general information form, a three-day food consumption record, the International Physical Activity Questionnaire Short Form (IPAQ SHORT FORM), the Perceived Stress Scale (PSS), the Dietary Self-Efficacy Scale (DESS), and the General Well-Being Scale Short Form (GWBS-SF) were used. At the 8th week, when the intervention ended, and at the 6-month follow-up, the Perceived Stress Scale (PSS), Dietary Self-Efficacy Scale (DESS), and General Well-Being Scale Short Form (GWBS-SF) were repeated. Anthropometric measurements and body composition analyses conducted as part of the study (body weight, height, BMI, waist-to-height ratio, waist circumference, hip circumference, neck circumference, waist-to-height ratio waist-to-hip ratio, total body fat (kg and %), lean body mass (kg and %), body water (L ), basal metabolic rate (kcal)) were performed at weeks 0, 2, 4, 6, and 8, as well as 6 months after the intervention ended. Anthropometric measurements were taken using standard measurement techniques, while body composition analyses were performed using the INBODY 270 device. Anthropometric indices (Lipid Accumulation Product Index - LAP, Visceral Adiposity Index - VAI, Conicity Index - CI, Body Shape Index - ABSI, Abdominal Volume Index - AVI, Body Adiposity Index - BAI, Body Roundness Index - BRI, Anthropometric Risk Index - ARI) calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters. Participants' biochemical test results were used to develop individualized dietary plans and to observe changes in biochemical findings during the weight loss process. No new blood tests were requested from the participants in this study. The biochemical data used in the study (fasting blood glucose, triglycerides, total cholesterol, HDL-C, LDL-C, TSH, ALT, AST, HbA1c) were obtained from laboratory results recorded in the participants' health records and dating back to the past 3 months. Note: This trial was retrospectively registered. Data collection was completed prior to registration in ClinicalTrials.gov.

• Study Type: Interventional
• Enrollment (Actual): 72
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Altındağ
    • Ankara, Altındağ, Turkey (Türkiye)
      • Ankara Medipol University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Female participants aged 25-55 years
• Body mass index (BMI) between 25 and 35 kg/m²
• having a history of weight fluctuations
• Willingness to participate and provide informed consent

Exclusion Criteria:

• Presence of cardiovascular disease
• Chronic kidney disease
• Hypertension
• Diagnosis of Type 1 or Type 2 diabetes mellitus
• Pregnancy or breastfeeding
• Use of any medication or dietary supplement for weight loss or fat reduction
• Engagement in intense physical activity
• No having a history of weight fluctuations
• Menopausal status
• Failure to attend scheduled follow-up visits
• Non-adherence to the intervention protocol for three consecutive days

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: 3 Meal Group; Participants followed a weight-loss diet consisting of 3 main meals per day.	Behavioral: 3-meal diet plan; A personalised weight-loss diet that reduces daily calorie intake by 500-700 kcal. Group 1 followed the diet for 8 weeks, consisting of 3 main meals a day.
Experimental: 6 Meal Group; Participants followed a weight-loss diet consisting of 3 main meals and 3 snacks per day.	Behavioral: A dietary intervention comprising 3 main meals and 3 snacks; A personalised weight-loss diet that reduces daily calorie intake by 500-700 kcal. Group 1 followed the diet for 8 weeks, consisting of 3 main meals and 3 snacks per day.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight (kg)	Body weight measured using a calibrated digital scale	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Body mass index (kg/m²)	Calculated as body weight in kilograms divided by height in metres squared	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Height (cm)	Height measured using a stadiometer with participants standing upright, feet together, in Frankfurt plane position.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Waist circumference (cm)	Waist circumference was measured using a non-stretch tape measure along the midline between the lowest rib and the iliac crest, with the individual standing with their feet together and arms at their sides in a relaxed position.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Hip circumference (cm)	Hip circumference was measured using a non-stretchable tape measure across the widest part of the hips, with the individual standing upright, feet together and arms at their sides	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Neck circumference (cm)	During neck circumference measurements, participants were positioned upright with their arms at their sides and their feet together. The measurements were taken by the researcher, who stood opposite the participant, using a non-stretchable tape measure around the neck near the shoulder.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
waist-to-height ratio	Waist-to-height ratio calculated by dividing waist circumference (cm) by height (cm).	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
waist-to-hip ratio	Waist-to-hip ratio calculated by dividing waist circumference (cm) by hip circumference (cm).	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
basal metabolic rate (kcal)	The measurements were taken using bioelectrical impedance analysis (BIA) with the INBODY 270 device.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Body Fat mass (kg)	The measurements were taken using bioelectrical impedance analysis (BIA) with the INBODY 270 device.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Lean body mass (kg)	The measurements were taken using bioelectrical impedance analysis (BIA) with the INBODY 270 device.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Percentage of lean body mass(%)	The measurements were taken using bioelectrical impedance analysis (BIA) with the INBODY 270 device.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Body fat percentage (%)	The measurements were taken using bioelectrical impedance analysis (BIA) with the INBODY 270 device.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Total body water (L)	The measurements were taken using bioelectrical impedance analysis (BIA) with the INBODY 270 device.	Baseline, Weeks 2, 4, 6, and 8, and 6 months post-intervention
Lipid accumulation product index-LAP	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (waist circumference(cm) and triglycerides (mmol/L))	Baseline, Week 8 and 6 months post-intervention
Visceral adiposity index-VAI	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (waist circumference (cm), body mass index(kg/m²),HDL-C (mmol/L) and triglycerides (mmol/L)).	Baseline, Week 8 and 6 months post-intervention
Conicity index - CI	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (waist circumference (m),Body weight (kg), Height (m) )	Baseline, Week 8 and 6 months post-intervention
A body shape index-ABSI	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (waist circumference (m), BMI(kg/m²) and heigh(m))	Baseline, Week 8 and 6 months post-intervention
Abdominal volume index-AVI	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (waist circumference (cm), hip circumference (cm)).	Baseline, Week 8 and 6 months post-intervention
Body adiposity index-BAI	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (Hip circumference (cm), Height (m)).	Baseline, Week 8 and 6 months post-intervention
Body roundness index-BRI	Calculated using validated formulas based on anthropometric measurements and relevant biochemical parameters (Waist circumference (m), Height (m)).	Baseline, Week 8 and 6 months post-intervention
Anthropometric risk index-ARI	Anthropometric Risk Score (ARS) is a composite score calculated by scoring each anthropometric parameter (BMI, waist circumference, waist-to-hip ratio, and waist-to-height ratio) based on established reference cutoff values and summing the individual scores.	Baseline, Week 8 and 6 months post-intervention
Fasting blood glucose (mg/dL)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
Triglycerides (mg/dL)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
Total cholesterol (mg/dL)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
HDL cholesterol (mg/dL)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
LDL cholesterol (mg/dL)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
Thyroid stimulating hormone (TSH) (µIU/mL)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
Alanine aminotransferase (ALT) (U/L)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention
Aspartate aminotransferase (AST) (U/L)	No additional blood samples were collected from participants. Biochemical data were obtained from existing health records, reflecting results from the previous 3 months, measured after a minimum 8-hour fasting period using standard laboratory methods.	Baseline, Week 8 and 6 months post-intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
perceived stress level	Assessed using the Perceived Stress Scale. Scores on the Perceived Stress Scale-14 range from 0 to 56, with a higher score indicating a greater perception of stress (a worse outcome). No cut-off point has been established for the scale.	Baseline, Week 8 and 6 months post-intervention
dietary self-efficacy	Assessed using the Dietary Self-Efficacy Scale. Scores on the Dietary Self-Efficacy Scale range from 11 to 55, with a higher score indicating greater dietary self-efficacy (a better outcome). No cut-off point has been established for the scale.	Baseline, Week 8 and 6 months post-intervention
General Well-Being	Assessed using the General Well-Being Scale Short Form. Scores on the General Well-being Scale Short Form range from 14 to 70, with a higher score indicating a higher level of well-being (a better outcome). No cut-off point has been established for the scale.	Baseline, Week 8 and 6 months post-intervention

Collaborators and Investigators

• Sponsor: Ankara Medipol University
• Investigators: Study Director: Elif Dadak Yıldırım, PhD(c), Ankara Medipol University; Principal Investigator: İlknur G Yıldırım, Asst. Prof., Ankara Medipol University

Study record dates

Study Major Dates

• Study Start (Actual): August 4, 2025
• Primary Completion (Actual): October 1, 2025
• Study Completion (Actual): May 1, 2026

Study Registration Dates

• First Submitted: April 30, 2026
• First Submitted That Met QC Criteria: May 8, 2026
• First Posted (Actual): May 13, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Dietary Intervention; Weight Management; Meal Frequency; weight cycle
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Body Weight Changes; Weight Loss; Weight Gain; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Weight Cycling; Overweight; Obesity
• Other Study ID Numbers: AMU-EC143-2026; EC-2026-143 (Other Identifier: Ankara Medipol University Ethics Committee)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared to protect participant privacy and confidentiality. All data were collected under informed consent with assurances of anonymity

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No