Dynamic Effects of Different Dietary Interventions on Weight and Biochemical Markers

This randomized controlled trial (RCT) aims to evaluate the dynamic effects of various dietary interventions on body weight and biochemical markers among healthy adults. Participants aged 18-65 years with a normal body mass index (BMI 18.5-24.0) will be recruited from the community. Exclusion criteria include metabolic diseases, unstable weight, medication use, or pregnancy.

Participants will be randomly assigned to one of seven groups: 1) normal diet (100% energy), 2) time-restricted eating (16+8, 100% energy), 3) time-restricted eating (16+8, 75% energy), 4) alternate-day fasting (75% energy), 5) 5+2 fasting (75% energy), 6) low-calorie diet (75% energy), and 7) very low-calorie diet (45% energy). The intervention consists of a 1-week baseline phase, a 4-week dietary intervention phase, and a 4-week recovery phase.

Primary outcomes include changes in body weight, while secondary outcomes include body composition, cardiovascular health indicators (e.g., blood pressure, cholesterol), inflammation markers, and liver/kidney function. Biological samples (blood, urine, and feces) will be collected at multiple time points to facilitate multi-omics analyses, including proteomics, metabolomics, metagenomics, and DNA methylation.

The study aims to compare the short-term effects of different dietary interventions and explore underlying biological mechanisms. Findings will provide evidence for public health policies and dietary guidelines related to weight management and metabolic health.

This study is a randomized controlled trial (RCT) designed to investigate the effects of different dietary interventions on body weight, body composition, and various biochemical indicators. The study will also incorporate multi-omics analyses to explore the dynamic biological mechanisms underlying these effects.

Study Background The increasing burden of obesity and chronic diseases has raised global concerns about effective dietary strategies. Recent dietary approaches, such as intermittent fasting (e.g., 16:8, alternate-day fasting, and 5:2 fasting) and continuous caloric restriction, have shown potential benefits in weight management and metabolic health. However, there is a lack of systematic comparisons between these dietary interventions and insufficient understanding of their dynamic biological effects.

This study aims to compare the short-term impacts of various dietary interventions and identify the biological mechanisms influencing weight and metabolic changes. Multi-omics analyses will include proteomics, metabolomics, metagenomics, DNA methylation etc. to provide a comprehensive understanding of these effects.

Study Design

This RCT will recruit 84 healthy adults (12 participants per group), aged 18-65 years, with a normal BMI (18.5-24.0). Participants will be randomly assigned to one of seven groups:

Normal diet group: Daily intake of 100% energy requirements, adjusted individually based on each participant's basal metabolic rate (BMR).

16+8 time-restricted eating group (100% energy): Participants will consume 100% energy within an 8-hour eating window and fast for the remaining 16 hours.

16+8 time-restricted eating group (75% energy): Participants will consume 75% of their energy requirements within the 8-hour eating window.

Alternate-day fasting group: Participants alternate between "feeding days" (125% energy requirements) and "fasting days" (25% energy requirements).

5+2 intermittent fasting group: Participants consume 95% energy requirements for 5 consecutive days and 25% energy requirements for 2 fasting days.

Low-calorie diet group (75% energy): Participants will reduce daily caloric intake to 75% of energy requirements, consumed evenly across three meals.

Very low-calorie diet group (45% energy): Participants will reduce daily caloric intake to 40% of energy requirements (\~800 kcal/day).

The study will span 9 weeks and include three phases:

Baseline phase (1 week): Participants consume their usual diet, and baseline measurements are taken.

Intervention phase (4 weeks): Participants adhere to their assigned dietary intervention.

Recovery phase (4 weeks): Participants return to their usual diet. Participants will be monitored closely throughout the study to ensure adherence to the intervention and the stability of other lifestyle factors (e.g., physical activity).

Outcome Measures Primary outcome: Changes in body weight. Secondary outcomes: Changes in body composition (waist circumference, BMI, body fat percentage), cardiovascular indicators (e.g., blood pressure, cholesterol levels), inflammation markers (e.g., IL-6, IL-8), and liver/kidney function.

Biological samples (blood, urine, and feces) will be collected at baseline, weekly during the intervention phase, and at weeks 5 and 8 of the recovery phase. Samples will be analyzed using multi-omics techniques, including proteomics, metabolomics, metagenomics, DNA methylation, etc. to identify dynamic biological changes associated with the dietary interventions.

Data Collection and Analysis Participants' data will include questionnaires, anthropometric measurements, biochemical tests, and multi-omics results. Blood samples, urine samples, and fecal samples (2 will be collected at each time point. Data will be analyzed to compare group differences in primary and secondary outcomes, with additional exploration of the underlying biological mechanisms through omics analyses.

Ethical Considerations The study has received ethical approval from the Institutional Review Board for Public Health and Nursing Research, Shanghai Jiao Tong University School of Medicine. Informed consent will be obtained from all participants before enrollment. Participant privacy and data confidentiality will be strictly maintained throughout the study.

Significance This study will provide a comparative analysis of different dietary interventions and their impacts on weight and metabolic health. The inclusion of dynamic multi-omics analyses will offer new insights into the biological mechanisms underlying these effects. The findings will contribute valuable evidence for the development of dietary guidelines and public health strategies for weight management and chronic disease prevention.

Eligibility Criteria:
Inclusion Criteria:

1. Participants aged 18-65 years.
2. BMI between 18.5 and 24.0.
3. Willing to voluntarily sign the informed consent form and comply with group assignments and intervention protocols.

Exclusion Criteria:

1. Diagnosed with metabolic diseases such as hypertension, diabetes, or dyslipidemia.
2. Diagnosed with uncontrolled psychiatric disorders.
3. Diagnosed with severe underlying diseases, such as renal failure, heart failure, or cancer.
4. Currently taking medications that may affect study outcomes (e.g., antihypertensive, antidiabetic, or lipid-lowering drugs).
5. Women in the perimenopausal stage or with irregular menstrual cycles.
6. Pregnant women.
7. Current smokers.
8. Unstable weight within the past three months (fluctuations exceeding 4 kg).