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Ann Nutr Metab. 2008;52(4):261-6. doi: 10.1159/000140517. Epub 2008 Jul 10.

Ramadan fasting and the GH/IGF-1 axis of trained men during submaximal exercise.

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Institut Supérieur du Sport et de l'Education Physique, Gafsa, Tunisia.



The aim of this study was to explore possible changes in body composition, blood glucose regulation, plasma growth hormone (GH), insulin-like growth factor 1 (IGF-1), insulin-like growth factor-binding protein-3 (IGFBP-3), and insulin concentrations of trained athletes in response to the intermittent fasting and dehydration of Ramadan observance.


Nine trained male rugby players (age 19 +/- 2 years, height 1.78 +/- 0.74 m) were tested 3 times: before Ramadan (C), at the end of the first week (R1), and during the fourth week (R2). They performed a progressive cycle ergometer test at each visit. The work rate was increased in 6-min stages corresponding to 20, 30, 40, 50 and 60% of W max. Substrate oxidation was evaluated by indirect calorimetry. On each occasion, substrate and plasma hormone concentrations were measured at rest and at the end of the exercise.


Ramadan fasting induced a significant decrease in body mass and body fat (R2 vs. C, p < 0.001). Plasma concentrations of glucose, insulin, GH, IGF-1 and IGFBP-3 did not change significantly between C and R2, either at rest or following exercise.


Ramadan fasting induces positive changes in body composition without disturbing glucose regulation or activity of the GH/IGF-1 system.

[Indexed for MEDLINE]

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