Network Meta-analysis of Intermittent Fasting and Cardiometabolic Risk

Effect of Intermittent Fasting Strategies on Cardiometabolic Risk: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

Intermittent fasting is a method of restricting calories over a defined period of time and includes regimens such as whole-day fasting, alternate-day fasting, and time-restricted feeding. There is emerging evidence that intermittent fasting or energy restriction might be more beneficial than continuous energy restriction for some risk factors. The effect of intermittent fasting on risk factors associated with obesity, diabetes, and cardiovascular disease, however, is not clear. The European Association for the Study of Diabetes (EASD) has yet to make any recommendations regarding the role of intermittent fasting in the management of diabetes. To inform the update of the EASD Clinical Practice Guidelines for Nutrition Therapy, tthe Diabetes and Nutrition Study Group (DNSG) of the EASD has commissioned a systematic review and network meta-analysis of randomized controlled trials of the effect of different intermittent fasting strategies on established cardiometabolic risk factors. The findings generated by this proposed knowledge synthesis will shape guide current guidelines and improve health outcomes by educating healthcare providers and patients, and by guiding future research design.

Study Overview

• Status: Active, not recruiting
• Conditions: Cardiovascular Diseases; Inflammation; Hypertension; Obesity; Diabetes; Metabolic Syndrome; Dyslipidemias; PreDiabetes; NAFLD; Gout; Cardiometabolic Syndrome
• Intervention / Treatment: Dietary supplement: Intermittent Fasting

Detailed Description

Background: 'Intermittent fasting' is currently the most popular trending diet, yet its clinical utility remains unclear. Previous systematic reviews and meta-analyses of intermittent fasting have been limited by a narrow focus on weight loss, one specific method of intermittent fasting, and/or a subset of participants who would be the least likely to benefit. Other issues have included unexplained heterogeneity, incorrect analyses and/or lack of assessment of the certainty of the evidence. There is emerging evidence that intermittent fasting may improve cardiometabolic risk markers independent of calories. However, there is a lack of certainty about the effectiveness of intermittent fasting on overall cardiometabolic risk across different health conditions, and the differences between the various methods of intermittent fasting. The European Association for the Study of Diabetes (EASD) has yet to make any recommendations regarding the role of intermittent fasting in the management of diabetes. To inform the update of the EASD Clinical Practice Guidelines for Nutrition Therapy, the Diabetes and Nutrition Study Group (DNSG) of the EASD has commissioned a systematic review and network meta-analysis (an approach which has the advantage over traditional pairwise meta-analyses of being able to assess simultaneously multiple interventions) to assess the effect of the different strategies of intermittent energy restriction (intermittent fasting) versus continuous energy restriction and ad libitum diets on cardiometabolic risk in randomized controlled trials and assess the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Objective: To assess simultaneously the effect of the various strategies of intermittent energy restriction (intermittent fasting), continuous energy restriction, and ad libitum diets on body weight and other cardiometabolic risk factors in a systematic review and network meta-analysis of randomized trials using the GRADE approach.

Design: Each systematic review and meta-analysis will be conducted according to the Cochrane Handbook for Systematic Reviews of Interventions and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for network meta-analyses (PRISMA-Network).

Data sources: MEDLINE, EMBASE, and The Cochrane Central Register of Controlled Trials (Clinical Trials; CENTRAL) will be searched using appropriate search terms. These searches will be supplemented by hand searches of references of included studies. Abstracts will be included and no language restrictions will be used.

Study selection: The investigators will include randomized controlled trials (RCTs) that are >=3-weeks duration investigating the effect of intermittent fasting, continuous caloric restriction and/or ad libitum diets on cardiometabolic risk factors in adults.

Data extraction: Two or more investigators will independently extract relevant data. Standard computations and imputations will be used to derive missing variance data. All disagreements will be resolved by consensus.

Risk of bias: Risk of bias will be assessed using the Cochrane Risk of Bias (RoB) Tool by the two or more investigators.

Outcomes: There will be 10 outcome clusters. The primary outcome will be body weight. Secondary outcomes will be other markers of adiposity (BMI, body fat, waist circumference); glycemic control (glycated blood proteins [HbA1c, fasting blood glucose, postprandial blood glucose, fasting blood insulin, homeostasis model assessment of insulin resistance [HOMA-IR]); established therapeutic lipid targets (LDL-cholesterol, non-HDL-cholesterol, apolipoprotein B [apo B], HDL-cholesterol, triglycerides); blood pressure (systolic blood pressure and diastolic blood pressure); markers of NAFLD (intrahepatocellular lipids [IHCL], alanine aminotransferase [ALT], aspartate aminotransferase [AST]); uric acid; and markers of inflammation (CRP).

Data synthesis: The investigators will perform a network meta-analysis comparing all the interventions simultaneously. These interventions will include alternate day fasting, cyclical whole day fasting, time restricted feeding, continuous energy restriction, and ad libitum diet in a single analysis by combining both direct and indirect evidence across the selected network of studies. Separate pooled analyses will be conducted for each cardiometabolic risk factor using the random-effects network meta-analysis. Intrasitivity will be adjudged using incoherence. Global method of incoherence (design-by-treatment interaction) and inconsistency factors (disagreement between direct and indirect estimates) will be used to estimate incoherence. A-priori subgroup analyses (health status, age, control diet energy restriction, diet supervision, study design, follow-up, feeding control, randomization, energy balance, baseline body weight, funding source, and ROB) will be performed. Separate analysis will be performed in people with diabetes. Publication bias will be assessed if there are ≥10 comparisons. The overall certainty of the evidence for each outcome will be assessed with GRADE using the CINeMA approach.

Evidence Assessment: The certainty of the evidence for each outcome will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Knowledge translation plan: The results will be disseminated through interactive presentations at local, national, and international scientific meetings and publication in high impact factor journals. Target audiences will include the public health and scientific communities with interest in nutrition, diabetes, obesity and cardiovascular disease. Feedback will be incorporated and used to improve the public health message and key areas for future research will be defined. Applicant/Co-applicant decision makers will network among opinion leaders to increase awareness and participate directly as committee members in the development of future guidelines.

Significance: The proposed project will be the most comprehensive synthesis and evaluation of the totality of evidence on the role of intermittent fasting in cardiometabolic health. These findings will aid in strengthening current guidelines and improve health outcomes by informing shared clinical decision making between healthcare providers and patients and guiding future research.

• Study Type: Observational
• Enrollment (Anticipated): 25

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5C 2T2
      • Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital
    • Toronto, Ontario, Canada
      • Faculty of medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Adults of all health statuses.

Description

Inclusion Criteria:

• Randomized controlled trials in humans
• Intermittent fasting intervention
• Continuous energy restriction, ad libitum diet, or other intermittent fasting diet as comparators
• Diet duration ≥1 weeks
• Data for at least one prespecified outcome
• Viable outcome data

Exclusion Criteria:

• Non-human studies
• Observational studies
• Children
• Multi-modal interventions
• Diet duration < 1 weeks
• No viable outcome data
• Lack of suitable comparator

Study Plan

How is the study designed?

Design Details

• Observational Models: Other
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Studies with intermittent fasting; Studies with intermittent fasting strategies.	Dietary supplement: Intermittent Fasting; Methods of intermittent fasting strategies, continuous energy restriction, and ad libitum diet.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight	Body weight in kg	Through study completion, up to 20 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adiposity - BMI	Body mass index (BMI) in kg/m2	Through study completion, up to 20 years
Adiposity - Waist circumference	Waist circumference in cm	Through study completion, up to 20 years
Adiposity - Body fat	Body fat in % (relative units)	Through study completion, up to 20 years
Glycemic control - HbA1c	Glycemic control - HbA1c	Through study completion, up to 20 years
Glycemic control - fasting plasma glucose (FPG)	Fasting plasma glucose (FPG) in mmol/L	Through study completion, up to 20 years
Glycemic control - 2h plasma glucose (2h-PG)	2h plasma glucose (2h-PG) during a 75g oral glucose tolerance test (OGTT) in mmol/L	Through study completion, up to 20 years
Glycemic control - fasting plasma insulin (FPI)	Fasting plasma insulin (FPI) in pmol/L	Through study completion, up to 20 years
Glycemic control - homeostasis model assessment of insulin resistance (HOMA-IR)	Homeostasis model assessment of insulin resistance (HOMA-IR)	Through study completion, up to 20 years
Established blood lipid targets - LDL-cholesterol (LDL-C)	LDL-cholesterol (LDL-C) in mmol/L	Through study completion, up to 20 years
Established blood lipid targets - non-HDL-cholesterol (non-HDL-C)	non-HDL-cholesterol (non-HDL-C) in mmol/L	Through study completion, up to 20 years
Established blood lipid targets - apolipoprotein B (apo B)	Apolipoprotein B (apo B) in g/L	Through study completion, up to 20 years
Established blood lipid targets - triglycerides	Triglycerides in mmol/L	Through study completion, up to 20 years
Established blood lipid targets - HDL-cholesterol (HDL-C)	HDL-cholesterol (HDL-C) in mmol/L	Through study completion, up to 20 years
Blood pressure - Systolic blood pressure (SBP)	Systolic blood pressure (SBP) in mmHg	Through study completion
Blood pressure - diastolic blood pressure (DBP)	Diastolic blood pressure (DBP) in mmHg	Through study completion, up to 20 years
Markers of non-alcoholic fatty liver disease (NAFLD) - Intrahepatocellular lipids (IHCL)	Intrahepatocellular lipids (IHCL) in % (relative units)	Through study completion, up to 20 years
Markers of non-alcoholic fatty liver disease (NAFLD) - alanine transaminase (ALT)	Alanine transaminase (ALT) in U/L	Through study completion, up to 20 years
Uric acid	Uric acid in mmol/L	Through study completion, up to 20 years
Markers of inflammation - CRP	CRP in mg/dL	Through study completion, up to 20 years

Collaborators and Investigators

• Sponsor: University of Toronto

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2020
• Primary Completion (Anticipated): June 1, 2022
• Study Completion (Anticipated): August 1, 2022

Study Registration Dates

• First Submitted: March 16, 2022
• First Submitted That Met QC Criteria: March 24, 2022
• First Posted (Actual): April 4, 2022

Study Record Updates

• Last Update Posted (Actual): April 4, 2022
• Last Update Submitted That Met QC Criteria: March 24, 2022
• Last Verified: March 1, 2022

More Information

Terms related to this study

• Keywords: Randomized controlled trial; Weight loss; Blood pressure; Uric acid; inflammatory markers; Systematic review and meta-analysis; Glycemic control; Intermittent fasting; Cardiometabolic risk factors; Blood lipids; Adiposity; Continuous energy restriction; Network metanalysis; Clinical practice guideline; NAFLD markers
• Additional Relevant MeSH Terms: Pathologic Processes; Glucose Metabolism Disorders; Metabolic Diseases; Disease; Insulin Resistance; Hyperinsulinism; Lipid Metabolism Disorders; Cardiovascular Diseases; Syndrome; Inflammation; Metabolic Syndrome; Dyslipidemias
• Other Study ID Numbers: DNSG-IF

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

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