Ramadan is one of the sacred pillars of Islam, and Muslims fast for a total of 29 to 30 days each year, abstaining from all forms of nourishment from sunrise to sunset. During long summer days, fasting during Ramadan may pose risks of dehydration and poor calorie and nutrient intake for bariatric surgical patients [1]. Muslims are allowed to eat freely from sunset to sunrise, but the extended fasting hours may result in increased hunger and a tendency to eat quickly upon breaking the fast, potentially leading to gastrointestinal (GI) symptoms and dumping syndrome (DS). Moreover, metabolic bariatric surgery (MBS) impacts the eating behavior of patients during fasting and can result in additional adverse effects [2]. Specifically, individuals who have undergone laparoscopic sleeve gastrectomy (LSG) typically have a reduced capacity to consume food compared to non-operated individuals after breaking the fast.

The objective of this study is to explore the challenges faced by patients who have undergone LSG during Ramadan fasting. To the best of our knowledge, this study is one of the few that addresses this under-researched topic. It can also assist physicians in providing guidance to Muslim patients regarding the feasibility of fasting during Ramadan while considering their MBS procedures. Furthermore, this study aims to investigate the relationship between the duration of time since surgery and the ability to fast during Ramadan.

An online survey, designed prospectively, was conducted with two groups: the LSG group included 218 randomly selected patients who had undergone LSG within the past year, identified from our Bariatric Surgery Registry (we reached out to Muslim LSG patients listed in our registry over the past year through telephone communication, providing them with comprehensive study details and securing verbal consent, and a control group which consisted of 83 volunteer individuals with obesity who had not undergone bariatric surgery. Within the LSG group, patients were categorized based on the time elapsed since surgery: 1–3, 3–6, 6–9, and 9–12 months. All participants were Muslims who observed Ramadan annually.

All participants, including LSG patients and controls, received a survey link and two structured questionnaires via WhatsApp (Meta Platforms, Inc.). The first questionnaire was completed before Ramadan, and the second was completed immediately after Ramadan. The questionnaires collected demographic data such as age, sex, weight, body mass index, surgery date, and any relevant medical conditions. No personally identifiable information was requested from the participants.

Patients were asked about their fasting practices during Ramadan post-bariatric surgery, including the number of fasting days and the duration since their surgery. Hunger and satiety perception were measured using a 0 to 10 analog scale [3] and recorded before and during Ramadan. Hunger levels were assessed before the Iftar meal (the main meal consumed after sunset), while satiety levels were evaluated 3 hours after Iftar. Participants documented their weight before and at the end of fasting, with weight loss reported as a percentage of total weight loss (TWL).

Participants were asked to provide detailed records of their food and beverage intake for 24 hours on 2 consecutive days, both before and during the final week of Ramadan. A qualified dietitian used standard calorie charts to estimate calorie intake and analyze macronutrient composition [1]. Adverse GI symptoms, such as vomiting, diarrhea, and constipation, were recorded using Yes/No questions. The presence of DS criteria in LSG patients during Ramadan fasting was evaluated based on the Sigstad scoring system [4].

Statistical analysis

Statistical analysis was performed using the IBM SPSS version 20.0 (IBM Corp.). The significance level (α) was set at 0.05. Qualitative data were described using counts and percentages. Quantitative data were summarized as mean and standard deviation. Continuous and categorical variables were compared using paired samples of the Student t-test and chi-square test, respectively.

A total of 218 LSG patients and 75 volunteer controls participated in the survey. The demographics and anthropometric measurements are shown in Table 1. Among the patients, 153 (70.2%) fasted for the entire month of Ramadan, while 69 of the controls (92.0%) did the same. The relationship between fasting duration and postoperative time is presented in Table 2. However, it is worth noting that 35 LSG patients (16.1%) did not observe fasting during Ramadan.

Table 1 . Demographics and anthropometric measurements.

Characteristic	LSG group	Control group
No. of subjects	218	75
Female sex	162 (74.3)	57 (76.0)
Age (yr)	34.9 ± 7.0 (29–58)	35.8 ± 4.0 (30–60)
Body weight (kg)
Preoperative	128.0 ± 6.0	127.0 ± 7.0
Postoperative	85.6 ± 8.0
Body mass index (kg/m2)		NA
Preoperative	46.9 ± 3.0 (35.6–54.3)	46.9 ± 1.1 (34.8–53.2)
Postoperative	31.1 ± 2.0 (24.7–36.8)	NA
TWL (%)	33.1 ± 3.0

Values are presented as number only, number (%), or mean ± standard deviation (range)..

LSG, laparoscopic sleeve gastrectomy; NA, not applicable; TWL, total weight loss..

Table 2 . Relation between duration of fasting and mean postoperative time.

Variable	LSG group (n = 218)						Control group (n = 75)
	<3 mo	3–6 mo	6–9 mo	9–12 mo	Total	Postoperative duration (mo)
No. of subjects	55	44	58	61	218
Postoperative time (mo)	1.1 ± 0.2	4.9 ± 1.2	8.1 ± 1.7	10.2 ± 1.9		7.1 ± 1.3
Fasting status
No fasting	35	-	-	-	35 (16.1)	0.9 ± 0.1	6 (8.0)
<2 wk	16	-	-	-	16 (7.3)	1.1 ± 0.2	0 (0)
2–4 wk	4	8	2	-	14 (6.4)	2.8 ± 0.7	0 (0)
Entire month	-	36	56	61	153 (70.2)	8.9 ± 1.7*	69 (92.0)

Values are presented as number only, mean ± standard deviation, or number (%)..

LSG, laparoscopic sleeve gastrectomy..

*p = 0.01, significant difference..

The hunger/satiety assessment for all participants is displayed in Table 3; in LSG patients, there were no differences in hunger and satiety scores during fasting and non-fasting periods. However, when these scores were compared with those in the control group the differences were significant.

Table 3 . Hunger and satiety scores in the patients and controls who fasted for the entire month during pre-Ramadan and Ramadan fasting period.

Score	Pre-Ramadan (non-fasting)	Ramadan (fasting)	p-value
Hunger score
Patients (n = 153)	3.6 ± 1.2	3.7 ± 1.2	0.09
Controls (n = 69)	6.7 ± 1.8	5.7 ± 1.7	0.08
p-value	0.01	0.04
Satiety score
Patients (n = 153)	7.8 ± 1.9	8.1 ± 2.0	0.06
Controls (n = 69)	3.2 ± 0.8	4.3 ± 1.6	0.06
p-value	0.01	0.02

Values are presented as mean ± standard deviation..

All participants fasted for the entire month..

The mean 24-hour fluid intake in fasting patients decreased by 30.5% compared to non-fasting days before Ramadan (from 1.9 to 1.3 L, p = 0.01) (Table 4). No significant symptoms of dehydration or renal impairment requiring medical attention were observed in fasting patients. However, controls experienced a 14.3% decrease in mean 24-hour fluid intake during fasting (p = 0.02). Analysis of 24-hour nutrient intake in fasting patients showed low energy and protein consumption (Table 5). Survey responses about patients’ meals during Ramadan indicated low protein and high carbohydrate/fat content.

Table 4 . Mean daily fluid intake for all participants.

Variable	Patients (n = 183)				Controls (n = 75)
	Fasted entire Ramadan (n = 153)		Did not fast (n = 35)		Fasted entire Ramadan (n = 69)		Did not fast (n = 6)
	Pre-Ramadan	Ramadan			Pre-Ramadan	Ramadan
Daily fluid intake (L)	1.9	1.3 (↓30.5%)	1.8 (↓5.2%)		2.8	2.4 (↓14.3%)	2.6 (↓7.1%)
p-value		0.01	0.06			0.02	0.07

Table 5 . Mean 24-hour nutrient intake during a Ramadan fasting day and a non-fasting day.

Variable	Pre-Ramadan (non-fasting)	Ramadan (fasting)	p-value
Energy (kcal)	766.5*	623.5	<0.05
Carbohydrate (g)	96.2	86.5
Sugar (g)	20.2	24.9
Protein (g)	35.6*	21.6	<0.05
Fat (g)	26.4	22.8

*p < 0.05..

Among the patients who fasted the whole month of Ramadan, 139 patients (90.8%) experienced weight loss, with a mean TWL of 7.2% ± 2.0%. The relation between weight loss and time elapsed after surgery is illustrated in Table 6. The mean postoperative duration for the 14 patients (9.2%) who did not lose weight was 7.8 ± 1.3 months (Table 6). In the control group, 11 (15.9%) experienced weight loss, 49 (71.0%) had no change in weight, and 9 (13.0%) gained weight; the mean percentage of weight loss in the control group was 2.5% ± 0.3%.

Table 6 . Weight loss according to post-LSG duration in the patients who fasted for entire month of Ramadan (n = 153).

	Postoperative time (mo)				Total	Mean postoperative time (mo)
	<3	3–6	6–9	9–12
No. of LSG patients	0	44	48	61	153
TWL (%)
No weight loss	-	1	12	1	14 (9.2)	7.8 ± 1.3
<5	-	1	20	60	81 (52.9)	8.9 ± 1.9
5–15	-	42	16	-	58 (37.9)	5.8 ± 1.1

Values are presented as number only, number (%), or mean ± standard deviation..

LSG, laparoscopic sleeve gastrectomy; TWL, total weight loss..

Occasional GI symptoms were present in 94 of the 153 patients who fasted the whole month of Ramadan. Some patients had more than one symptom (Fig. 1).

Figure 1. Gastrointestinal symptoms in patients who fasted the whole of Ramadan. GI, gastrointestinal.

Among LSG patients, only 70.2% completed the full month of Ramadan fasting, compared to 92.0% in the control group. The mean postoperative duration for LSG patients was 8.9 ± 1.7 months, indicating a positive correlation between the duration and fasting ability. Longer duration allowed for better oral intake, enhancing fasting capacity [5,6]. Anatomical and hormonal changes resulting from surgery, such as reduced stomach size and impacts on ghrelin levels and glucagon-like peptide 1 secretion, contribute to the ability of LSG patients to fast. Strong spiritual values also play a role in their determination to fast despite medical advice [7–9]. Patients who fasted for only a portion of Ramadan had shorter postoperative durations (1.1 ± 0.2 months and 2.8 ± 0.7 months). Early postoperative weeks limited their ability to tolerate oral intake within the restricted Ramadan timeframe, hindering fasting. Conversely, 16.1% of patients refrained from fasting altogether due to food intolerance after breaking the fast or concerns about weight loss with changes in food quality and frequency. These patients were in the early postoperative phase (mean of 0.9 ± 0.1 months). A recent consensus among surgeons highlighted the importance of specialized nutrition during Ramadan fasting after MBS, with 70% recommending a delay of 6 to 12 months before fasting initiation [10]. Our study found an average time of 8.9 ± 1.7 months for patients to achieve full fasting after surgery.

Patients showed decreased hunger and increased satiety compared to control subjects starting from the first month after surgery, regardless of fasting or non-fasting periods. The findings of Al-Ozairi et al. [1] and Howick et al. [11] can be attributed to changes in eating behavior, physiological changes associated with MBS, and potential sociocultural influences of fasting on appetite and satiety.

The mean 24-hour fluid intake in our LSG patients significantly decreased during Ramadan fasting compared to a non-fasting day and was lower than that of the control group. Studies on body hydration during Ramadan fasting have yielded conflicting results, with some indicating no changes while others suggesting potential indications of dehydration [1,6,12,13]. The reduction in stomach size among sleeved patients restricts the volume of fluids they can consume, particularly in the early postoperative period. Additionally, patients maintain the same frequency of water intake habits before and during fasting, resulting in reduced fluid intake during the limited non-fasting hours [12].

Daldal et al. [6] found significant weight loss after 25 days of Ramadan fasting in LSG patients. In our survey, 90.8% of LSG patients who fasted the entire month of Ramadan experienced weight loss; the majority (58.3%) had less than 5% TWL and were 9 to 12 months after surgery. In the remaining 41.7% of patients, weight loss ranged between 5% and 15% TWL, and patients were mostly 3 to 6 months after surgery. Weight loss was observed more during the early postoperative period; early postoperative dietary restrictions lead to a more liquid diet, reducing the amount of food intake and enhancing weight loss [11]. As weight loss after surgery is not linear, but faster during the early weeks/months and slower later on, it is very likely that time elapsed plays a role independently from Ramadan fasting. We believe that weight loss can be primarily attributed to surgical factors (anatomic and hormonal) [14] with a partial contribution from Ramadan fasting and its spiritual aspects on appetite and satiety. In a few cases, failure to lose weight or weight regain after MBS has been linked to loss of control over overeating, which typically occurs later after surgery [15]. However, in our study, patients who did not lose weight or lost less than 5% of their total weight had an average postoperative duration of 7.8 ± 1.3 months and 8.9 ± 1.9 months, respectively. In the control group, weight loss during fasting was not significant, with a mean percentage of weight loss of 2.5%. Studies conducted on the general population during Ramadan fasting have shown minimal weight loss, followed by weight regain after Ramadan ends [16]. Healthy individuals typically return to their previous weight within about 1 month after Ramadan through their regular diet [17].

In this study, body composition was not measured to determine if weight loss resulted from fat or lean mass loss. However, the analysis of 24-hour food intake in the patients’ group revealed a significant reduction in total calories and protein intake during fasting compared to non-fasting days. Al-Ozairi et al. [1] conducted a similar study that showed LSG patients consumed fewer calories and less protein, resulting in a reduction in lean body mass. A previous study also reported decreased calorie consumption and reduced protein intake after MBS [18]. Current guidelines recommend a minimum daily protein intake of 90 g and emphasize the importance of increasing awareness about protein intake during fasting, especially after MBS [19]. Sufficient protein intake is a crucial factor for weight loss, as it is the most challenging to digest and provides the greatest feeling of satiety [1].

Occasional adverse GI symptoms in our patients’ group were minimal, with constipation and vomiting being more prevalent at 3 months but improving over time. These findings align with Ostruszka et al. [20]. Postoperative vomiting is common in 30% to 60% of MBS patients during the initial months, primarily due to the reduced stomach size [6]. LSG patients who fast during Ramadan are at risk of experiencing dumping symptoms due to the rapid emptying of the smaller stomach and consumption of large meals high in sugar and fat [21]. However, despite these risk factors, only 2.5% of our patients met the criteria for DS according to the Sigstad scoring system. To prevent dehydration and minimize GI complications, patients should avoid overeating during non-fasting hours, ensure sufficient fluid intake, and increase protein consumption.

This study was conducted as an online survey, and our findings relied on participant self-reporting and remote memory. Additionally, the absence of body composition analysis after fasting to determine whether weight loss involved fat or lean muscle loss adds to the study’s limitations. However, this survey is one of the few studies addressing an under-researched topic, and it was prospectively designed. It involved a comparison between fasting and non-fasting periods within the same patient. Moreover, this work holds the potential to inspire future large-scale, prospective, controlled multi-center studies on this significant topic.

In conclusion, the majority of LSG patients (70.2%) were able to fast for the entire month of Ramadan. The mean postoperative time for these patients was 8.9 ± 1.7 months; the longer the postoperative time the greater the ability to fast. Fasting patients reported decreased feelings of hunger, increased satiety, and mild GI symptoms. Fluid consumption, total calorie intake, and protein intake significantly decreased during fasting. Weight loss in LSG patients was moderate and primarily attributed to surgery, with a partial contribution from Ramadan fasting. In order to fast for the entire month, patients may be advised to consider postponing surgery for a few months after Ramadan, avoid overeating during non-fasting hours, and ensure sufficient fluid consumption and protein intake during fasting.

Ethical statements

The current study was approved by the Institutional Review Board of Alexandria University (No. 00012098). All participants provided verbal consent to participate in this study.

Authors’ contributions

Conceptualization: TNA

Formal analysis, Investigation: All authors

Writing–original draft: All authors

Writing–review & editing: All authors

All authors read and approved the final manuscript.

Conflict of interest

All authors have no conflicts of interest to declare.

Funding/support

None.

Data availability

The data presented in this study are available upon reasonable request to the corresponding author.