Metabolic diseases have reached pandemic levels, raising concerns about metabolic health. Their prevalence is expected to rise in the future. Ramadan fasting (RF), a yearly Islamic practice, involves abstaining from eating and drinking from sunrise until sunset. The effects of RF vary due to multiple factors, including the duration of fasting per day, variations in diet quality and quantity, and the level of physical activity observed during Ramadan, leading to heterogeneity in reported outcomes.
The main aim of the thesis was to test the hypothesis that 18 hrs/day RF causes systemic metabolic changes, which could be detected non-invasively by MRI and basic blood samples. The secondary aims were to study these changes on healthy female and male groups. Als, as part of this assessment, the validation of automated muscle and fat volumes measurements method and the optimisation of MR image acquisitions had to be undertaken to improve the automated measurements.
Methods: the validation of automated muscle volume measurements involved comparing them with the gold standard manual method in a population undergoing temporal changes in muscle volume. Subsequently, various MR sequences were assessed to identify the ones that produced images with the highest contrast-to-noise ratio and were most compatible with the automated threshold method.
To evaluate the effect of RF on the body mass index (BMI), muscle and subcutaneous adipose tissue volumes, liver and muscle ectopic lipids, abdominal visceral and subcutaneous fat (AVF and ASF), fasting blood glucose and insulin (FBG and FBI), and blood lipid profiles were monitored before, during, and a month after Ramadan. Additionally, the dietary intake and physical activity habits were assessed during and one month after the end of RF.
Results: the automated and manual measurements of muscle volume exhibited strong agreement. Optimal results were obtained using fat-only and water-only images for automated measurements of muscle and fat volumes.
After RF, significant reductions were observed in BMI and skeletal muscle volume, while FBG, LDL, and ectopic muscle lipid increased in both males and females. AVF significantly decreased in males, and there was a tendency towards a decrease in ASF in both sexes. Although protein intake did not fall below the recommended guideline level, it was significantly lower during RF compared to the non-RF period.
Discussion: the study findings indicate that automated volume measurements demonstrate comparability to the gold standard method while saving time. The declines in BMI and abdominal adipose fats are factors in improving cardiometabolic health. The adverse increases in FBG, LDL, and ectopic muscle lipid could be attributed to circadian rhythm disruption, which impacts hormonal levels, lipolysis and hepatic gluconeogenesis. The decrease in muscle volume may be associated with the limited eating window during fasting.
Conclusion: an 18-hour RF regimen can lead to reductions in BMI and adipose fat tissues, although caution is warranted regarding the effects on muscle volume, FBG, and LDL. To counteract these effects, aligning with the wider literature, it is recommended to enhance protein intake and include resistance exercise. Furthermore, the study underscores the reliability of automated volume measurements as a time-efficient substitute for manual methods.