Study design
This is a randomized clinical trial. The flow chart of the study is presented in Fig 1. We will conduct a randomized clinical trial for 8 weeks. This intervention is conducting in the nutrition clinic of Shahid Beheshti University of Medical Sciences in Tehran, Iran, to evaluate the effect of TRF on anthropometric indices, body composition, eating behavior, stress, BDNF and LBP levels in over weight and obese women with food addiction.
Sample size
The number of participants was calculated according to the alterations in the main variable weight. Determining the sample size for this study is based on how many samples should be selected so that the difference between the mean weight loss of TRF group from the control group is at least 2.3 kg(29), so that this difference with a probability of 95% (α=0.05) and power of 80% (β=20%) is statistically significant. Using this method, the number of samples in each group was estimated to be 26, which, taking into account the 20% fall in the samples, will be entered by 30 people in each group.
Study population
Overweight and obese women (Body mass index (BMI) between 26 - 39.9 kg/m2) with food addiction were recruited from nutrition clinic of Shahid Beheshti University of Medical Sciences. the diagnosis of food addiction will be based on Food Addiction Scale(30).Over weight and obese women that obtain the necessary score will be enrolled in the study and written informed consent was obtained at the baseline.
Inclusion and exclusion criteria
For the present study, 60 adult women with the following inclusion criteria will be included: aged 20-65 years, BMI between 26 and 39.9 kg/m2, Willingness to participate in the study, Confirmation of food addiction after obtaining the necessary score from the relevant questionnaire.
Patients will be excluded if: 1) they are pregnant or lactating 2) have any diseases such as cancer, diagnosed diabetes, newly diagnosed hypothyroidism, renal or liver failure 3) have a weight loss diet in the last 2 months4) current smokers5) take any antibiotics in the last 1 months 6) take any medication affecting study outcomes regularly, 7) use probiotic products (probiotic supplements, yogurt, cheese, cakes, biscuits and probiotic pasta) continuously (more than once a week) in the last month 8) use weight-loss or appetite-suppressing medications 9) perimenopause women. Also, Participants who refuse to continue the study, have medical conditions needing to take antibiotics or have difficulties in fasting for 14 hours a day in the intervention group will be excluded.
Randomization
Participants will be randomly allocated into two groups: the group receive the time restricted feeding or the control group and will be followed up for 8 weeks. Stratified Blocked Randomization method is used to randomly assign people to two groups. The sequencing will be generating by one of the authors (AS) who is not going to assign participants into the study and allocation concealment will be ensured, as the author will not release the randomization code until the patient has been recruited into the trial by other authors (HI and BKh), which takes place after all baseline measurements have been completed. Participants are classified into over weight (26-29.9), grade 1 (30-34.9) and grade 2 obesity (35-39.9) based on body mass index and randomly assigned to one of control or TRF groups. Separate randomization is performed within each group for each BMI class. The size of the blocks is 4, two allocations are given to TRF group (A) and two allocations to Control Group (B). 6 different permutations of AABB, ABAB, BBAA, BABA, ABBA and BAAB will be created.
Intervention
In this study, patients receive the relevant diets for 8 weeks based on the group they are placed in. In both groups, after calculating the amount of calories required by each individual using the Mifflin formula (31)as much as 300-500 kcal will be deducted from the total energy required for each person and accordingly, the low calorie diet plan is given to each individual. The diet in each group will be consist of 50-55% carbohydrates, 15-20% protein and 30% fat. Patients in the TRF group will receive their meals from 10 hours a day from 10 am to 8 pm(32) while the control group will have less than 12 hours fasting.
Adherence
In order to control the participants in terms of adherence to the regimen and prevent the loss of samples, they will be followed up twice a week by phone call and the data of the patients with more than 90% compliance with the intervention will be analyzed.
Study outcome
The outcome of this clinical trial are the changes in weight, BMI, hip circumferences, Waist-to-hip ratio, fat mass, muscle mass, Stress level, Eating behavior, Plasma BDNF and LBP levels.
Procedure
After obtaining the informed consent, the general profile sheet will be completed for each patient. Also, at the beginning of the study, the weight of each patient with light clothing and with the accuracy of 100 grams and the height of each patient in a shoeless state are measured by the meter mounted on the wall with an accuracy of 0.5 cm. Then, BMI of patients is calculated and waist and hip circumferences are measured using meters with 0.5 cm accuracy. Waist-to-hip ratio is calculated. Then, their fat mass and muscle mass are measured by bioelectrical impedance analysis. The participants' daily physical activity level will be measured using the Standard Physical Activity Questionnaire (MET). The validity of this questionnaire has been confirmed(33). Stress levels of subjects at the beginning and end of the study will be assessed using the Perceived Stress Questionnaire (PSS-14)(34). The scoring method is that based on the 5-degree spectrum, a score of 0-4 is awarded to each item (never score 0 and most of the time score 4). Phrases 4-5-6-7-10 and 13 are scored inversely (never score 4 to most of the time score 0). Then, by collecting the items, the overall score is 0-56, which the higher score indicates more perceived stress(34). Eating behavior will be measured using three-factor eating questionnaire at the beginning and the end of the study. The questionnaire consists of 18 questions in 3 sections about cognitive factors related to eating, hunger and emotional eating. The questionnaire is scored by questions 1 to 13 on a four-point Likert scale from one (definitely incorrect) to four (definitely correct). Questions 14 to 17 also have a separate Likert scale, and question 18 has an 8-degree Likert scoring scale. The higher rating in the cognitive factors associated with eating indicates greater limitation in receiving calories to control body weight. Also, higher hunger score indicates a person's greater susceptibility to eating in response to hunger and higher emotional eating score indicates a person's greater susceptibility to excessive eating. The validity of this questionnaire has been measured in Iran (35).
In order to measure blood biochemical parameters 5 cc of venous blood samples will be taken from the site of the bracing vein and after 12 to 14 hours fasting by the laboratory technician at the beginning and the end of the study. Blood samples taken in tubes containing sodium citrate anticoagulants will be collected and centrifuged in the laboratory of the Shahid Beheshti Nutrition Faculty for 15 minutes at a speed of 500 round per minute and serums will be stored at -80°C until the tests are performed. Plasma BDNF and LBP levels will be measured by ELISA method with BDNF kit and LBP kit with the intra-assay and inter- assay CV of < 10% and <12%, respectively for both kits in the laboratory of the Nutrition Institute of Shahid Beheshti University of Medical Sciences.
Assessment of dietary intake
In this study, to assess participant’s dietary intake, at the beginning of the study, at the end of the fourth and eighth weeks of the study, three days of dietary recall about one holiday and two non-holidays will be completed through face-to-face or telephone interviews. Common household measurement tools (glass, cup, soup bowl, plates, teaspoon and tablespoon) will be provided to assist subjects in estimating the portion size of the food. Dietary intake will be analyzed with Nutritionist IV (N4) software
Assessment of physical activity level
MET physical activity questionnaire will be completed for them(33).
Statistical analysis
In this study, data analysis is performed by SPSS software version 11.5. Paired t test will be used to compare the mean of quantitative variables with normal distribution in each group between the beginning and the end of the study and the t test will be used to compare their mean between the two groups at the beginning and end of the study. In the case of quantitative variables with non-normal distribution, Wilcoxon and Mann-Whitney tests are used, respectively. In case of the variables measured three times during the study (beginning, fourth week and eighth week), repeated ANOVA test will be used. Covariance analysis is used to eliminate the effect of quantitative confounding factors. Chi-square test is used to compare the qualitative variables between the two groups and regression analysis is used to eliminate the effect of qualitative confounding.
Ethical considerations
Obese and overweight women who meet the inclusion criteria will be completely informed about the protocol of the study. The protocol of this study was approved by ethics committee of Shahid Beheshti University of medical sciences and is in conformity with the declaration of Helsinki (approved number IR.SBMU.NNFTRI.REC.1399.03).
Modification of study
Any modifications to the protocol which may impact on the conduct of the study, potential benefit of the patient or may affect patient safety, including changes of study objectives, study design, patient population, sample sizes, study procedures, or significant administrative aspects will require a formal amendment to the protocol. Such amendment will be agreed upon by NNFTRI ( Natinal Nutrition and Food Technology Institute), and approved by ethics committee of Shahid Beheshti University of medical sciences prior to implementation. Administrative changes of the protocol are minor corrections and/or clarifications that have no effect on the way the study is to be conducted. These administrative changes will be agreed upon by NNFTRI. The ethics committee of Shahid Beheshti University of medical sciences may be notified of administrative changes at the discretion of NNFTRI.