Health impact of fasting in Saudi Arabia during Ramadan: association with disturbed circadian rhythm and metabolic and sleeping patterns

PLoS One. 2014 May 8;9(5):e96500. doi: 10.1371/journal.pone.0096500. eCollection 2014.


Background: Muslims go through strict Ramadan fasting from dawn till sunset for one month yearly. These practices are associated with disturbed feeding and sleep patterns. We recently demonstrated that, during Ramadan, circadian cortisol rhythm of Saudis is abolished, exposing these subjects to continuously increased cortisol levels.

Hypothesis: Secretory patterns of other hormones and metabolic parameters associated with cortisol, and insulin resistance, might be affected during Ramadan.

Protocol: Ramadan practitioners (18 males, 5 females; mean age ±SEM = 23.16±1.2 years) were evaluated before and two weeks into Ramadan. Blood was collected for measurements of endocrine and metabolic parameters at 9 am (±1 hour) and again twelve hours later.

Results: In Ramadan, glucose concentration was kept within normal range, with a significant increase in the morning. Mean morning concentration of leptin was significantly higher than pre-Ramadan values (p = 0.001), in contrast to that of adiponectin, which was significantly lower (p<0.001). These changes were associated with increased insulin resistance in morning and evening. Concentrations of hsCRP were lower during Ramadan than those during regular living conditions, however, normal circadian fluctuation was abolished (p = 0.49). Even though means of liver enzymes, total bilirubin, total protein and albumin were all decreased during Ramadan, statistically lower means were only noted for GGT, total protein, and albumin (p = 0.018, 0.002 and 0.001 respectively).

Discussion: Saudi Ramadan practitioners have altered adipokine patterns, typical of insulin resistance. The noted decreases of hsCRP, liver enzymes, total protein, and albumin, are most likely a result of fasting, while loss of circadian rhythmicity of hsCRP is probably due to loss of circadian cortisol rhythm.

Conclusions: Modern Ramadan practices in Saudi Arabia, which are associated with evening hypercortisolism, are also characterized by altered adipokines patterns, and an abolished hsCRP circadian rhythm, all likely to increase cardiometabolic risk.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose*
  • Circadian Rhythm / physiology*
  • Fasting / blood*
  • Female
  • Humans
  • Hydrocortisone / blood*
  • Islam
  • Male
  • Saudi Arabia
  • Sleep / physiology*
  • Sleep Disorders, Circadian Rhythm / blood
  • Sleep Disorders, Circadian Rhythm / physiopathology
  • Young Adult


  • Blood Glucose
  • Hydrocortisone

Grant support

This project was supported by the deanship of research at King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia under grant number (HiCi/1432- 6-2) as part of a main research study conducted by the “Saudi Diabetes Study Research Group”. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.