Effect of Intermittent Fasting Diet on Glucose and Lipid Metabolism and Insulin Resistance in Patients with Impaired Glucose and Lipid Metabolism: A Systematic Review and Meta-Analysis.

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• IF does not require calorie restriction which may result in greater compliance
• IF does not restrict macronutrients such as CHO and fats, so may avoid the exclusion of key nutrients e.g. healthy fats and wholegrains.
• IF may have fewer adverse effects on daily routines and quality of life, which may mean adherence is easier.
• Improved glucose and lipid metabolism may prevent the development of chronic health conditions such as T2D, CVD and cancer.

Management of glucose and lipid metabolism can be achieved through weight reduction using dietary interventions such as very low calorie or CHO diets, which may be effective but difficult to sustain long term. An alternative approach for weight management, improved insulin resistance and subsequent prevention of comorbitities e.g. Type 2 Diabetes (T2D), Cardiovascular Disease (CVD) and cancer, is Intermittent Fasting (IF). such as time restricted or periodic fasting.

This study summarises the effects of IF dietary interventions lasting less than three months in overweight and obese women with Metabolic Syndrome, defined as the presence of any metabolic dysfunction including obesity, hyperglycaemia, dyslipidaemia or hypertension.

The meta-anlaysis was carried out following PRISMA guidelines. A literature search in PubMed and Medline using the keywords obesity/overweight, IF diet, metabolic syndrome, RCT’s and humans resulted in 10 studies with 12 types of intervention for analysis. The following outcomes were evaluated: glucose and lipid metabolism, insulin resistance, weight loss and blood pressure.

Results were analysed in R software using mean differences and 95% confidence intervals, and either random or fixed effects depending on the Cochrane’s Q and I(2) statistics. Funnel plots were inspected for potential bias and Egger’s regression tests for publication bias. There were significant differences before and after the interventions for all glucose and lipid metabolism markers as well as body weight and systolic blood pressure :

Glucose metabolism:

• Fasting glucose reduced by 0.15mmol/L
• Insulin plasma reduced by 13.25uUI
• HbA1c reduced by 0.08%
• HOMA-IR (insulin resistance index) reduced by 0.31 on average

Lipid metabolism:

• Total cholesterol reduced by 0.32mmol/L
• LDL reduced by 0.22mmol/L
• Triglyceride reduced by 0.04mmol/L

Weight loss:

• Body weight reduced by 1.87kg
• BMI reduced by 0.8kg/m2
• Waist circumference reduced by 2.08cm

Blood pressure:

• Systolic reduced by 2.58mmHg
• Diastolic reduced by 3.12mmHg

Despite limitations of the meta-analysis, this study demonstrates IF has therapeutic effects on those with disordered lipid and glucose metabolism, and may prove to be an effective and sustainable approach.

• IF may be an effective alternative to restricted calorie or CHO diets for weight management with the associated benefits of glucose and lipid metabolism.
• IF has been shown to have therapeutic effects on individuals with impaired glucose and lipid metabolism.
• IF may be considered as a sustainable lifestyle choice rather than a ‘weight loss’ programme such as a very low calorie diet, which can result in poor quality of life and subsequent reduced adherence.
• Since it may take time for impaired glucose and lipid metabolism to progress to more serious disease states, establishing IF as an early intervention, may be considered as a prudent form of preventative medicine.
• IF has shown to have other health benefits such as reduced blood pressure and may be considered as adjuvant therapy.

• Compares the effects of IF on different ethnicities, sex and age categories
• Evaluates the effect of IF on other disease states e.g. cancer, auto-immune conditions
• Assesses the response of other biomarkers e.g. inflammatory cytokines
• Compares different types and durations of IF on health biomarkers (eg periodic, time restricted)