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, 8 (4), e60917

Relative Metabolic Stability, but Disrupted Circadian Cortisol Secretion During the Fasting Month of Ramadan


Relative Metabolic Stability, but Disrupted Circadian Cortisol Secretion During the Fasting Month of Ramadan

Suhad Bahijri et al. PLoS One.


Background: Chronic feeding and sleep schedule disturbances are stressors that exert damaging effects on the organism. Practicing Muslims in Saudi Arabia go through strict Ramadan fasting from dawn till sunset for one month yearly. Modern era Ramadan practices in Saudi Arabia are associated with disturbed feeding and sleep patterns, namely abstaining from food and water and increasing daytime sleep, and staying awake and receiving food and water till dawn.

Hypothesis: Strict Ramadan practices in Saudi Arabia may influence metabolism, sleep and circadian cortisol secretion.

Protocol: Young, male Ramadan practitioners were evaluated before and two weeks into the Ramadan. Blood samples were collected at 9.00 am and 9.00 pm for measurements of metabolic parameters and cortisol. Saliva was collected serially during the day for cortisol determinations.

Results: Ramadan practitioners had relative metabolic stability or changes expected by the pattern of feeding. However, the cortisol circadian rhythm was abolished and circulating insulin levels and HOMA index were increased during this period.

Discussion: The flattening of the cortisol rhythm is typical of conditions associated with chronic stress or endogenous hypercortisolism and associated with insulin resistance.

Conclusions: Modern Ramadan practices in Saudi Arabia are associated with evening hypercortisolism and increased insulin resistance. These changes might contribute to the high prevalence of chronic stress-related conditions, such as central obesity, hypertension, metabolic syndrome and diabetes mellitus type 2, and their cardiovascular sequelae observed in the Kingdom.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.


Figure 1
Figure 1. Meal time and sleep patterns during the pre-fasting month of Shaaban and the fasting month of Ramadan.
Figure 2
Figure 2. Morning and evening values of salivary cortisol during a) the non-fasting and b) the fasting month.

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Grant support

This study 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 project conducted by “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.