Ramadan daily intermittent fasting reduces objectively assessed habitual physical activity among adults

Fasting during the holy month of Ramadan is considered as one of the five fundamental pillars of Islam, thus, an obligatory religious duty for all healthy Muslim adults. Ramadan is based on a lunar calendar where the duration varies between 29 and 30 days. Each year, this month shifts forward around 10 days in a Gregorian calendar. During this month, Muslims refrain from eating and drinking during daylight hours. The fast begins early morning after Suhoor (meal taken just before dawn) and ends with Iftar (meal taken at sunset) [1]. The duration between Suhoor and Iftar is the duration of fasting and this can vary based on geographical location and season [2]. For instance, it averages from 14 to 15 h in the Middle East and up to 20 or 21 h at higher latitudes (e.g. Scandinavian countries) during summer. This variability in fasting time alters the schedule of other daily living activities that have an impact on human health such as sleep and exercise [3].

Ramadan fasting has captured public attention in recent years due to the recent rise in popularity of daily intermittent fasting as means to improve health and reduce weight [4]. Ramadan fasting has been well documented in scientific literature [5‐8] where scientists have investigated the effects of fasting during Ramadan with respect to its impact on an individual’s biochemistry (e.g., glucose utilization) [9‐12], blood pressure [13], metabolism [14], bodyweight [11, 14], sleep [3, 9, 15] and general health [9, 16]. Much of these existing research considered the challenges of chronic illnesses such as diabetes and hypertension on fasting Muslims or focused on athlete’s performance during Ramadan Fasting [17, 18]. Although, there is a strong dose-response relationship with number of step count per day and reduced risk of all-cause mortality [19], the effect of Ramadan fasting on community daily physical activity in the literature is scarce [20, 21].

Few studies on effects of Ramadan fasting on physical activity were conflicting and moreover had smaller sample or absence of a control group. In one study, the accelerometer assessed total steps was lower during Ramadan in a sample of 11 subjects who fasted for ~ 10.3–10.5 h compared to post Ramadan period [22]. Another study involving total of 15 subjects showed physical activity did not change among fasting subjects throughout Ramadan [11]. Insufficient physical activity is one of the leading risk factors for diabetes, cardiovascular disorders, and their associated mortality [23, 24]. Research indicates that an optimal level / increased physical activity has a beneficial effect both on the disease by reducing blood glucose levels and blood pressure as well as on disease prevention [24, 25]. Ramadan fasting leads to interference in the sleep-wake cycles that become shifted/disturbed (e.g., taking daytime naps to make up for sleep loss during the night) [2]. Moreover, based on international recommendations, an individual should engage in at least 60 min of moderate to vigorous intensity physical activity daily for optimum health [24]. And at least 8000 steps/day can be equated to 20 min of moderate activity [26]. The intermittent fasting schedule during Ramadan poses a challenge in performing vigorous forms of physical activity because of the lack of immediate external energy supply in a fasting state, inability to refuel, inability to hydrate while fasting [27] Individuals can utilize non-daylight hours for physical activity but the hours after sundown often involve a busy schedule in which all day-to-day activities are planned. This scenario is specifically applicable individual living in Muslim majority countries where businesses typically remain open till midnight. During Ramadan, Muslim in general spend an increased amount of time in the evening religious prayers [23].

The physical activity of the non-Muslims living in a Muslim country may also be impacted during the month Ramadan, even though they do not fast. Indeed, during Ramadan in some Muslim-majority countries, working hours are shortened (e.g., ≤6 h per workday), which may also impact a non-faster’s daily routine (e.g., having more time to do activities that the individual would ordinarily not have time to do).

Therefore, the aim of the current study was to determine how physical activity is affected by daily intermittent fasting during the month of Ramadan among fasting and non-fasting individuals. We hypothesized that physical activity during Ramadan will be lowered among fasting individuals and might be higher among non-fasting individuals living in a Muslim-majority country because of working conditions and/or cultural influences.

In this study, physical activity before, during, and after Ramadan was quantitatively measured by using pedometers. Main findings of this study was that, in general, daily physical activity decreased during Ramadan and was still lower after Ramadan in individuals who fasted. Fasting status significantly affected physical activity during Ramadan, with non-fasting individuals performing more steps than fasting individuals during Ramadan.

In contrast to our findings, there was no effect of Ramadan fasting in few studies, when self-reported instruments were used to assess physical activity. For example, Al-Barha and Aljaloud [14] used a self-reported lifestyle questionnaire to ask male participants questions about their habitual daily physical activity levels. They found that the reported activity level (i.e., moderate or vigorous) of the participants in their study did not change significantly before Ramadan, during Ramadan (at weeks 2 and 3), and 6-weeks after Ramadan. Al-Hourani and Atoum [20] examined the activity levels of women before, during, and after Ramadan by using activity diaries. They also found that fasting during Ramadan had no significant effect on physical activity level.

Alsubheen and colleagues [11] examined the activity levels of 15 men during Ramadan by using a physical activity tracker. In their study both fasting and non-fasting did not change their physical activity during Ramadan compared to pre or post Ramadan months. However, the activity of non-fasting individuals was always higher than fasting participants pre, during and post Ramadan [11]. Racinais et al. (2012), compared 2 months of pre-Ramadan physical activity with Ramadan and post Ramadan months in 11 fasting men and found no significant changes [34]. Although there were shifts in when physical activity was performed during the days of Ramadan, overall energy expenditure did not change. Similar non-significant changes were found in a study involving 16 young teens where energy expenditure during Week 1 and Week 4 of Ramadan was like that of pre and post Ramadan periods [35]. In another study 10 obese and 10 non-obese particiants observing Ramadan fasting were studied. The physical activity energy expenditure among obese as well as non obese subjects did not change during Ramadan and post Ramadan was comparable to before the onset of Ramadan [36]. Although these studies used objective measures of physical activity, the small sample size (n < =16) was inherent in these studies.

In agreement with our study, a recent UAE based study showed reduced objective measures of physical activity during Ramadan among individuals that fasted 10.3 to 10.5 h daily [22].. In our study, the non-fasting participants increased physical activity in Ramadan but this was lately reduced to baseline values post-Ramadan. However, fasting individuals that decreased their physical activity during Ramadan did not recover one-month post-Ramadan (Fig. 1). Regular physical activity is important for health in general, and when integrated with fasting, this results in positive changes to the lipid profile of humans [21].

The data on preferred time to practice physical activity and preferred place for physical activity could explain the reasons why fasting individuals experienced a drop in step count. Other aspects of concern were that most of the fasting participants in this study were under the impression that their physical activity levels remained the same (50.2%) or was not reduced (18.7%) during Ramadan. Also, around 23.2% of the fasting participants preferred to practice physical activity late in the night or in late afternoon / evening just before Iftar (33.8%). Lack of available time in evening after iftar or late night is a potential factor having led to this observed lower step count. During fasting state it is not recommended to peform vigorous intensity physical activity, because body energy stores are at a lowest after 13–14 h of fasting and there is no opportunity to drink water and therefore a risk of dehydration [27], especially in hot and humid locations. Naturally, duration of physical activity during daytime time will be shorter if vigorous intensity activity is invovled. On the other hand, practicing late night physical activity will jeopardize duration of night time sleep which is likely to be interrupted by Suhoor early morning meal [37]. As a consequence, participants who prefer late night physical activity will be depriving themselves of enough sleep and accumulating sleep dept./deprivation [37, 38] and increased frequency of daytime napping [39]. This will indirectly affect physical activity levels in the consecutive days [40].

The main strength of this study is that objective measures of daily physical activity in the form of step counts was used. This is critical because, based on self-reports, 50% of the fasting participants in this study believed that their physical activity remained the same in Ramadan which is contrary to what pedometer data has revealed. Due to the COVID-19 pandemic at the time of the study, data collection was performed using web survey and through email contact. This gave a relatively low response rate from the participants. The participants of the study were members of a community physical activity program (probably more health conscious) and hence do not represent the general population. The questionnaire was administered only once after the physical activity data was collection. This is a potential limitation of recall bias. However, we believe that the main question in the study, “Did you practice full 30-day Ramadan fasting? (asked for each year) is less likely to lead to recall bias because Muslims in general hold themselves accountable to Ramadan fasting. Although pedometer provides objective measure of physical activity, it cannot provide the timing when the physical activity was performed, and as a result, we were unable to determine at what time of the day do participants engaged in physical activity and whether it was different among fasting and non-fasting individuals. However, in our survey we included a question to enquire preferred time for physical activity among participants during Ramadan. Finally, given that this study was conducted in a Muslim majority country the results may not be directly applicable to other settings where day to day activities remain unchanged during Ramadan.

Daily intermittent Ramadan fasting reduced the daily habitual physical activity among fasting individuals from Qatar. While non fasting individuals increased their physical activity during Ramadan, the fasting individuals reduce their physical activity specially during the first 2 weeks. More than half of the fasting individuals were not aware that their physical activity was actually reduced during Ramadan. Interventions should be targeted to promote physical activity both during as well as after Ramadan where physical activity levels begin to gradually recover. The preferred location by the participants parks, and walking trails can be potential targets to conduct physical activity interventions.