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Ramadan fasting, one of the five pillars of Islam occurs during the 9th lunar month of the Islamic calendar1. Throughout this holy month, Muslims are allowed to eat and drink only between the hours of sunset and dawn. As such, most Muslims typically consume two meals a day during this month: one immediately after sunset and the other just before dawn1.

While the spiritual effects of this practice are outside the scope of this article, there are numerous physical and biochemical changes that occur within the body during this period. It’s inevitable you or someone you know will be engaged in Ramadan while trying to adhere to their normal training program, be it hitting the gym, a team sport or a simple endurance sport such as running. Readers may be surprised to learn that there are a plenty of studies looking at the various health impacts of Ramadan. These studies encompass endurance and strength athletes as well as martial artists and even soccer and elite rugby players.

From a purely scientific standpoint, it is interesting to consider the physiological and biochemical effects of dramatically changing a simple factor such as the timing of food intake for a period of a month. Thankfully, there is enough published scientific to address most of these questions. ramadan sunset

Published Effects of Ramadan Are Contradictory

One of the first things to note when discussing the physiological effects of Ramadan is that there are contradictory findings. This is thought to be largely due to2:

  • Different ways in which Ramadan fasting is practised in different populations
  • Time that blood samples are collected in relation to the last meal
  • Seasonal and climatic differences during Ramadan
  • Differences in health, fitness and activity levels of study populations

To illustrate, for Muslims living in the Northern Hemisphere, daylight hours are significantly longer than those in the Southern Hemisphere. Likewise, for Muslims living in Australia, withholding fluid intake during winter months presents less of a challenge to dehydration than say Muslims living in warmer areas the US. Additionally, because there is such a narrow window of time during which to eat each day, it can be a challenge for researchers to obtain normal fasting blood samples, as Muslims are up early having a meal before the sun rises.

Nonetheless, simple before and after measures can provide useful information as to the various health effects of Ramadan.

Effects of Ramadan on Blood Glucose Control and Type 2 Diabetes

One of the key areas of interest concerning the effects of Ramadan is how it impacts blood sugar and type 2 diabetes control. While all studies have not yielded identical results, there is a general trend for Muslims with diabetes to exhibit better blood control during Ramadan3, 4. It seems that the extended period of fasting throughout the daytime tends to reduce blood glucose levels3.

Best Time of Day for Working Out During Ramadan

Another question that arises with Ramadan is whether it’s more optimal to workout at a certain time of day. For instance, will a workout straight after a meal in the evening be more conducive to better strength gains or does a workout in the middle of the day when the stomach is empty better? The answers  seem to lie in the type of exercise one performs.

A study looking at the effect of Ramadan on aerobic training found that performing aerobic training in a fasted state during Ramadan led to lower body weight and body fat percentage compared with when aerobic training was performed non-fasted5.

As for weight training, another study found that training in a fasted or fed state during Ramadan did not significantly affect body mass or composition in a group of Muslim bodybuilders6.

girl stretching ramadanAnother question to consider is the effect of Ramadan fasting on the performance of acute high-intensity exercise. Concerning this issue, one study found that the optimal time to conduct an acute high-intensity exercise session during the Ramadan fasting month is in the evening, after the breaking of the day’s fast7. In contrast, performing the high-intensity exercise session during the period of the daytime fast had a small to moderate, negative impact on performance.

Effects of Ramadan on Strength

Another question that has concerned researchers is the effect of Ramadan fasting on measures of maximal and functional strength. Does going without food repeatedly during the day affect performance of standard functional strength measures such the vertical jump and handgrip force? One study measuring these factors found that during the first week of Ramadan, strength performance is slightly reduced, but returns to near normal values by the 4th week of Ramadan. These findings are in keeping with the theory that the body can adapt to severe changes in either diet or exercise if given sufficient time8. Similar findings have been observed with the performance of endurance cyclist when switched from a high carbohydrate diet to a high-fat low carbohydrate diet over six weeks9.

Effects of Ramadan on Endurance Exercise

The other obvious question concerning Ramadan and exercise is its effect on endurance exercise performance. Again, there is a study to glean from, which looked at endurance performance in active Muslim men during Ramadan and before and after Ramadan. Consistent with other studies measuring different aspects of performance, during Ramadan endurance running performance was slightly compromised as measured by 30 minutes run @ 65% VO2max followed by 30 min time trial10. During Ramadan, subjects exhibited slightly low blood glucose concentrations, but measures such as average heart rate, blood lactate and ratings of perceived exertion were not significantly different.

Yet another study which assessed the effect of Ramadan on different measures of running performance found that during Ramadan, 5000-m running performance was slightly reduced compared with before Ramadan. This coincided with a small reduction in muscle performance as measured by maximal voluntary contraction of the knee extensor muscle. However, on measures of running efficiency or maximal aerobic power, there was no change11.

This short summary of research concerning the effects of Ramadan on various measures of physical performance suggests that there is little detrimental change in performance measures of strength and endurance. On the contrary, for individuals with type 2 diabetes or poor blood glucose control, evidence suggests that Ramadan can have beneficial effects on cardiovascular healthy, presumably due to the extended periods of abstinence from food during the month of Ramadan. An important issue that is overlooked when studying the effects of Ramadan is the tendency for the body to adapt to the stress of restricted food intake over a period of time.



  1. Trabelsi K, et al. Effects of ramadan fasting on biochemical and anthropometric parameters in physically active men. Asian Journal of Sports Medicine. 2011;2(3):134-144.
  2. Chaouachi A, et al. The effects of Ramadan intermittent fasting on athletic performance: Recommendations for the maintenance of physical fitness. Journal of Sports Sciences. 2012;30(S1): S53–S73.
  3. Meo SA & Hassan A. Physiological changes during fasting in Ramadan. J Pak Med Assoc. 2015 May;65(5 Suppl 1):S6-S14.
  4. M'guil M, et al. Is Ramadan fasting safe in type 2 diabetic patients in view of the lack of significant effect of fasting on clinical and biochemical parameters, blood pressure, and glycemic control? Clin Exp Hypertens. 2008 Jul;30(5):339-57.
  5. Trabelsi K, et al. Effects of fed- versus fasted-state aerobic training during Ramadan on body composition and some metabolic parameters in physically active men. Int J Sport Nutr Exerc Metab. 2012;22(1):11-8.
  6. Trabelsi K, et al. Effect of fed- versus fasted state resistance training during Ramadan on body composition and selected metabolic parameters in bodybuilders. J Int Soc Sports Nutr. 2013 Apr 25;10(1):23.
  7. Aziz AR, et al. Conducting an acute intense interval exercise session during the Ramadan fasting month: what is the optimal time of the day? Chronobiol Int. 2012;29(8):1139-50.
  8. Bouhlel H, et al. Effect of Ramadan observance on maximal muscular performance of trained men. Clin J Sport Med. 2013;23(3):222-7.
  9. Phinney SD, et al. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism. 1983;32(8):769-76.
  10. Aziz AR, et al. Effects of Ramadan fasting on 60 min of endurance running performance in moderately trained men. Br J Sports Med. 2010;44(7):516-521.
  11. Brisswalter J, et al. Effects of Ramadan intermittent fasting on middle-distance running performance in well-trained runners. Clin J Sport Med. 2011;21(5):422-7.
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