Effects of Different Dietary Models on Eating Behavior and Obesity Management in Overweight and Obese Individuals

NCT ID: NCT07055620

Last Updated: 2025-11-25

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 75 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-04-18
• Study Completion Date: 2025-11-12

Brief Summary

The aim of this study is to examine the effects of different diet models (Mediterranean diet, time-restricted feeding and standard diet application) applied to overweight and obese individuals on eating behavior and obesity management.

Sub-objectives can be listed as; Effects of different diet models on body composition, Effects of different diet models on dietary intake, Effects of different diet models on biochemical parameters (such as blood sugar, insulin resistance, lipid profile).

As a result, this study aims to contribute to the development of individualized nutrition counseling programs by determining effective diet strategies in obesity.

Detailed Description

Overweight and obesity are among the most significant risk factors for health globally, with more than 1 billion people expected to be obese by 2030. Turkey is projected to be among the countries at high risk of obesity by 2030. Furthermore, obesity is among the preventable risk factors for cardiovascular disease (CVD), cancer, diabetes, stroke, and chronic lung disease, among other noncommunicable diseases (NCDs). Overweight and obesity are widespread and increasing health problems worldwide. Excessive adiposity is associated with insulin resistance, lipid deterioration, and systemic inflammation. A 5-10% weight loss is known to improve metabolic outcomes such as blood sugar, lipid profile, and blood pressure. Individuals employ a variety of strategies to lose weight. Lifestyle interventions that encourage calorie restriction and increased physical activity are the most commonly prescribed interventions by healthcare and clinical practitioners. While continuous energy restriction is a more traditional method for reducing energy intake, intermittent fasting has emerged as a potential alternative in the last decade. Fasting is known as one of the world's oldest traditions and is practiced across various communities for cultural or religious reasons. Fasting has also been used as a treatment for illness in the past. Hippocrates, considered the father of modern medicine, emphasized the importance of fasting during illness with the saying, "Eating when you are sick is feeding your illness." Intermittent fasting (IF), or periods of voluntary abstinence from food and drink, is an ancient practice followed in various forms by many populations worldwide. Intermittent fasting involves fasting or restricting food intake for specific hours of the day or on specific days of the week. IF can be implemented in three different ways: alternate-day fasting, the 5:2 diet, and time-restricted feeding (TRF). Alternate-day fasting involves alternating days of food and drink consumption with days of fasting during which no energy-containing food or drink is consumed. In alternate-day fasting, approximately 20-25% of energy needs are met on fasting days. Modified fasting is also known as the 5:2 method. This eating pattern involves a very low-calorie diet for two non-consecutive days per week, followed by normal energy requirements without energy restriction for the other five days. Another approach, time-restricted feeding (TRF), is used to describe an eating pattern in which food intake is restricted to a time window of 8 hours or less each day. Among intermittent fasting diets, the TRF diet is a lifestyle intervention that restricts food intake to a fixed number of hours. Welton and colleagues reported that the ideal fasting period for positive weight change is 16 hours. In recent years, small-scale human studies demonstrating the importance of time-restricted eating have become widespread. Many of these studies, as in animal studies, have demonstrated the beneficial effects of intermittent fasting on human metabolism. TRF has been found to reduce energy intake, body weight, body fat, blood glucose, triglycerides, glucose tolerance, and inflammatory markers. It has been established that IF may be beneficial in reducing body weight, improving insulin resistance, and reducing infection by regulating circadian rhythms, gut microbial composition, and metabolism. Time-restricted eating has been suggested as a potential weight-loss strategy because it may be more acceptable due to the reduced burden of dietary restriction. Intermittent fasting reduces body fat storage and increases fat mobilization, oxidation, and ketone body production, resulting in weight loss. A study comparing intermittent fasting with low-energy diets found that, although body weight reductions were similar after three months of follow-up, the reduction in fat mass was greater in the intermittent fasting group.

The term "Mediterranean diet" reflects the food combinations typical of Mediterranean populations such as Greeks, Southern Italians, and Spaniards in the early 1960s. Lower rates of cardiovascular disease (CVD) and chronic diseases associated with aging in these populations led to its popularization. Since November 2010, the Mediterranean diet has been included on the list of the Intangible Cultural Heritage of Humanity by UNESCO, as it represents a heritage closely linked to cultures and lifestyles passed down through centuries and is the result of the complex socioeconomic development of Mediterranean populations.

Eating behavior changes from birth onward, depending on many factors. Eating, which is essential for life, can, in some cases, develop into a psychiatric disorder, or differences from normal eating behaviors can occur. Eating is not an automatic process, especially for young people. It is significantly influenced by the cultural, social, and psychological pressures individuals feel. In recent years, various theories have been developed to assess behaviors that can impair eating motivation, adequate food intake, and body weight control. "Emotional eating" refers to eating to cope with negative emotions and relieve stress by ignoring satiety signals without internal physiological hunger signals. "External eating" refers to eating in response to stimuli related to food consumption, regardless of hunger and satiety signals. "Restrictive eating" reflects the degree to which one deliberately restricts food intake.

Today, the prevalence of non-communicable diseases is increasing, and obesity is among the risk factors for these diseases. While many methods are used in the treatment of obesity, the role of medical nutrition therapy is crucial. Various methods are used in medical nutrition therapy for obesity. These methods include the calorie-restricted Mediterranean diet, the time-restricted eating model (a type of intermittent fasting), and standard dietary intervention. This study will evaluate the effects of these dietary models on individuals' body composition, dietary intake, and eating behaviors.

Conditions

Mediterranean Diet; Intermittent Fasting; Diet

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: SUPPORTIVE_CARE
• Blinding Strategy: NONE

Study Groups

Mediterranean diet

Mediterranean diet

Group Type: ACTIVE_COMPARATOR

Mediterranean diet

Intervention Type: OTHER

The group that will be applied the Mediterranean diet will be prepared with diet lists that include 35-40% carbohydrate, 15-20% protein and 35-45% fat (\>50% Monounsaturated Fatty Acid (MUFA)) of daily energy. The Mediterranean diet pyramid will be explained to the participants who will be applied the Mediterranean diet, and the portions and frequency of olive oil, nuts, olives, fish, yogurt, fruits and vegetables that they should consume will be planned by the dietitian. The Mediterranean diet pyramid recommends the frequency of foods that should be consumed daily, weekly and monthly. It recommends consuming fish and seafood at least twice a week, 2 portions of white meat, 2-4 portions of eggs, less than 2 portions of red meat, 1 portion or less of processed meat and less than 3 portions of dessert. It is recommended to consume 2 portions of dairy products, 1-2 portions of oil seeds and nuts, more spices, herbs, garlic and onions on a daily basis.

standard diet and time-restricted feeding

standard diet and time-restricted feeding

Group Type: ACTIVE_COMPARATOR

standard diet and time-restricted feeding

Intervention Type: OTHER

In time-restricted nutrition, the focus is on when the food is consumed rather than the type of food. However, in medical nutrition treatment of obesity, the content of the meals is also important along with the time (Soran and Öney 2022). As stated in the Turkish Nutrition Guide (TÜBER), it will be taken into account that 45-60% of the energy comes from carbohydrates, 10-20% from protein and 20-35% from fat (Ministry of Health, 2022). A time-restricted nutrition model will be implemented from intermittent fasting diet models. The time restriction will be planned as 8 hours of eating and 16 hours of fasting, suitable for the lifestyle of the individuals. The feeding time for individuals who agree to participate in the study will be determined as 11.00-12.00 and 19.00-20.00. Individuals will be given 2 main meals and the first meal will start with breakfast or lunch according to their wishes.

control group

standard diet

Group Type: ACTIVE_COMPARATOR

Standard diet

Intervention Type: OTHER

When writing the weight loss diets applied to the individuals in the standard diet group, it will be taken into account that 45-60% of the energy comes from carbohydrates, 10-20% from protein and 20-35% from fat, as specified in the Turkish Nutrition Guide (TUBER). It will be planned that 10% (preferably 7-8%) of the total energy from fat will come from saturated fats (fat found in animal foods, butter, tallow, tail fat), 12-15% from monounsaturated fats (olive oil, hazelnut oil, rapeseed oil) and 7-10% from polyunsaturated fats (corn, soy, sunflower and cottonseed oils containing n-6 fatty acids and fish, fish oil, walnut, flaxseed containing n-3 fatty acids). It will be stated that this ratio is 1 part solid oil, 1 part any vegetable oil and 1.5 or 2 parts olive oil among the oil types.

Interventions

Mediterranean diet

The group that will be applied the Mediterranean diet will be prepared with diet lists that include 35-40% carbohydrate, 15-20% protein and 35-45% fat (\>50% Monounsaturated Fatty Acid (MUFA)) of daily energy. The Mediterranean diet pyramid will be explained to the participants who will be applied the Mediterranean diet, and the portions and frequency of olive oil, nuts, olives, fish, yogurt, fruits and vegetables that they should consume will be planned by the dietitian. The Mediterranean diet pyramid recommends the frequency of foods that should be consumed daily, weekly and monthly. It recommends consuming fish and seafood at least twice a week, 2 portions of white meat, 2-4 portions of eggs, less than 2 portions of red meat, 1 portion or less of processed meat and less than 3 portions of dessert. It is recommended to consume 2 portions of dairy products, 1-2 portions of oil seeds and nuts, more spices, herbs, garlic and onions on a daily basis.

Intervention Type: OTHER

Standard diet

When writing the weight loss diets applied to the individuals in the standard diet group, it will be taken into account that 45-60% of the energy comes from carbohydrates, 10-20% from protein and 20-35% from fat, as specified in the Turkish Nutrition Guide (TUBER). It will be planned that 10% (preferably 7-8%) of the total energy from fat will come from saturated fats (fat found in animal foods, butter, tallow, tail fat), 12-15% from monounsaturated fats (olive oil, hazelnut oil, rapeseed oil) and 7-10% from polyunsaturated fats (corn, soy, sunflower and cottonseed oils containing n-6 fatty acids and fish, fish oil, walnut, flaxseed containing n-3 fatty acids). It will be stated that this ratio is 1 part solid oil, 1 part any vegetable oil and 1.5 or 2 parts olive oil among the oil types.

Intervention Type: OTHER

standard diet and time-restricted feeding

In time-restricted nutrition, the focus is on when the food is consumed rather than the type of food. However, in medical nutrition treatment of obesity, the content of the meals is also important along with the time (Soran and Öney 2022). As stated in the Turkish Nutrition Guide (TÜBER), it will be taken into account that 45-60% of the energy comes from carbohydrates, 10-20% from protein and 20-35% from fat (Ministry of Health, 2022). A time-restricted nutrition model will be implemented from intermittent fasting diet models. The time restriction will be planned as 8 hours of eating and 16 hours of fasting, suitable for the lifestyle of the individuals. The feeding time for individuals who agree to participate in the study will be determined as 11.00-12.00 and 19.00-20.00. Individuals will be given 2 main meals and the first meal will start with breakfast or lunch according to their wishes.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Being between 20-49 years old
• Having a BMI value between 25 kg/m2- 35 kg/m2
• Not having conditions that impair reality assessment ability and cognitive functions, preventing interviews or filling out scales
• Being literate
• Having a blood test done by a primary care physician within the last seven days
• Agreeing to participate in the study and signing the informed consent form

Exclusion Criteria

• Pregnant and breastfeeding women,
• Those who could not attend one or more interview sessions,
• Women who have entered menopause,
• Individuals who want to apply another diet model,
• Individuals who have a pacemaker or defibrillator implanted due to the theoretical possibility of interference with device activity due to the current field caused by impedance measurements,
• Those who have any chronic disease and are on a diet,
• Those who regularly use medications that affect metabolism,
• Those who use insulin and oral antidiabetic medications,
• Those who have allergies or intolerances to any food components of the Mediterranean diet (walnuts, hazelnuts, peanuts, almonds, etc.),
• Those who use vitamin/mineral supplements,
• Those who have a psychiatric disease diagnosed by a physician.
• In order to understand the effectiveness of the diet, individuals will be asked to maintain their physical activity levels. Therefore, individuals who want to increase their physical activity levels in addition to the applied diet will not be included in the study.

• Minimum Eligible Age: 20 Years
• Maximum Eligible Age: 49 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Selcuk University

OTHER

Sponsor Role: lead

Responsible Party

SUHİDE BİLGE HORZUM

dietician

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Ebru Bayrak

Role: STUDY_DIRECTOR

Selcuk University

Locations

Eda Ocak Nutrition and Diet Consultancy

Konya, Selçuklu, Turkey (Türkiye)

Countries

Turkey (Türkiye)

Other Identifiers

SBHORZUM

Identifier Type: -

Identifier Source: org_study_id