Systematic Dietary Interventions to Minimize Postoperative Weight Loss Following Orthognathic Surgery: a Randomized Controlled Trial

Objectives: This randomized controlled trial aimed to assess whether structured dietary interventions, implemented both before and after orthognathic surgery, could minimize postoperative weight loss during the first eight weeks.

Material and Methods: The study was conducted between April 2017 and April 2022, involving patients undergoing singleor bimaxillary surgery. Participants were randomly allocated into three groups: intervention 1 (nutritional tube feeding), intervention 2 (oral intake nutritional supplements), and control (standard care). Body composition was assessed using a body composition analyser (Tanita BC-418) at five time points: presurgery examination, admission, and follow-ups weeks 1, 3, and 8. Primary outcome was weight; secondary - BMI, fat mass, fat-free mass, total body water, and visceral fat rating. Compliance was assessed from patient questionnaires and hospitalization records based on adherence to the prescribed nutritional intake before and after surgery.

Results: In total 150 patients were included, without statistically significant differences in age (28.6 [SD 10.4] years, P = 0.7) and BMI (24.9 [SD 5.6], P = 0.72). All groups experienced significant weight loss postoperatively (week 1: P < 0.001; week 3: P < 0.001; week 8: P < 0.001), with control showing slightly greater loss at week 8 (-3.03 kg vs. -2.18 and -2.67 kg; P = 0.11). Compliance during hospitalization was higher in intervention 1 (71.8%) than intervention 2 (55.1%; P = 0.02). No significant differences were found in body mass index or body composition changes.

Conclusions: There was no statistically significant effect of systematic dietary interventions versus standard care on postoperative weight loss or body composition after orthognathic surgery. Higher adherence did not improve clinical outcomes.

J Oral Maxillofac Res 2026;17(2):e4

doi: 10.5037/jomr.2026.17204

Accepted for publication: 30 June 2026

Keywords: compliance; dietary supplements; orthognathic surgery; randomized controlled trial; weight loss.

INTRODUCTION

Orthognathic surgery is performed to correct dentofacial deformities that cannot be addressed through orthodontic treatment alone, particularly in early adulthood when natural growth has ceased. Patients with dentofacial deformities often suffer from various functional impairments, including diminished bite force, abnormal chewing patterns, restricted mandibular movement, and temporomandibular disorders [1-4].

Postoperative weight loss following orthognathic surgery is a well-recognized challenge in clinical practice, despite various efforts to optimize nutrition. Weight loss of 3 to 10 kg has previously been reported following orthognathic surgery [5]. A weight loss of approximately 3 kg may not be alarming in these patients, as they are often young and otherwise healthy, and such modest reductions are generally well tolerated. However, literature reports indicate that weight loss following orthognathic surgery can reach up to 10 kg in some cases, which may negatively impact postoperative recovery by exacerbating fatigue, delaying wound healing, and potentially affecting metabolic and immune function [5-8]. Careful monitoring and tailored nutritional support are, therefore, essential to mitigate these risks and promote optimal recovery.

Following orthognathic surgery, patients are generally advised to avoid chewing hard or crunchy foods for approximately 6 to 8 weeks. During the initial postoperative period, a liquid diet is recommended, followed by a gradual transition to a soft or puréed diet as healing progresses [9]. Elastics are often used postoperatively to guide the occlusion, but these can further increase the risk of nutritional deficiencies, dehydration, and weight loss [10]. These postoperative functional limitations, combined with imposed dietary restrictions, contribute to weight loss as a complication to orthognathic surgery [7,11]

Additionally, patients undergoing orthognathic surgery encounter metabolic and endocrine changes similar to those observed in states of starvation [12]. If nutritional requirements are not met within 48 hours postsurgery, catabolism can occur, negatively affecting postoperative recovery [5]. The recovery period after orthognathic surgery, which can last up to six months, is often marked by challenges such as difficulty eating and breathing, numbness, swelling, hematoma, limited mouth opening, and nausea [13]. Maximal swelling occurs within 48 to 72 hours postoperatively, and postoperative nausea and vomiting are reported in 40 to 60% of patients, often due to the ingestion of blood during surgery [8,13-15]. While research indicates that orthognathic patients generally feel well-informed about their surgery and postoperative care, many are surprised by the severity of their symptoms and the duration of recovery [8].

Various nutritional interventions and supplements, such as protein-enhanced drinks, have been explored to prevent postoperative weight loss. However, poor compliance with dietary supplementation remains a concern, often due to the texture or taste of the products [5,16], Few studies focus on the use of nasogastric feeding tubes in orthognathic patients, particularly those with maxillary fixation [16].

To address gaps in the literature, further research is needed to identify dietary interventions that can prevent excessive weight loss and improve recovery with fewer side effects. It is also important to determine whether patients are losing fat mass, fat free mass, or body water, and to explore the relationship between weight loss, overall well-being, and recovery.

The aim of this randomized controlled trial (RCT) is to determine whether systematic dietary interventions, administered pre- and postoperatively, can minimize weight loss in the first eight weeks after orthognathic surgery.

MATERIAL AND METHODS

Ethics

The study complies with the General Data Protection Regulation and was registered in the North Denmark Region’s record of processing activities (2008-58-0028). The trial was approved by the North Denmark Region Committee on Health Research Ethics (N-20160067). Informed written consent was obtained in accordance with current legislation.

Patients received oral information at the presurgery examination. They were given a one-month consideration period, starting from the time they received the written information until the day they received the oral information during the presurgery examination.

Patients were free to withdraw at any time without any consequence to their care or treatment.

Study design

The study was designed as a RCT and was conducted at Aalborg University Hospital in Denmark between April 18, 2017 and April 11, 2022. The study adhered to the CONSORT guidelines for RCTs [17]. The study has been registered as a clinical trial at Clinicaltrials.gov (No. 2016-130).

Study population

Between April 18, 2017 and April 11, 2022, adult patients (≥ 18 years) with dentofacial deformities scheduled to undergo single- or bimaxillary orthognathic surgery, including Le Fort I osteotomy and/or bilateral sagittal split osteotomy, were assessed for eligibility. Patients with syndromic conditions or cleft lip and palate were eligible for inclusion if they otherwise met the study criteria, although none of these patients were treated at this hospital or enrolled in this study. Inclusion criteria were age ≥ 18 years, planned orthognathic surgery, the ability to provide written informed consent, and willingness to comply with the study protocol. Exclusion criteria were age < 18 years or inability to provide written informed consent or comply with the study procedures. Participation was voluntary, and eligible patients who declined participation were not enrolled. All enrolled patients provided written informed consent prior to randomization to intervention 1, intervention 2, or the control group.

Standard protocol for orthognathic surgery patients

All orthognathic surgery patients attend a presurgery examination with the surgeon approximately 14 days before surgery. On the day before surgery, they complete an admission interview with a nurse and receive informed about pre-, peri- and postoperative precautions, including dietary guidelines. The standard protocol for their dietary guidelines is outlined in Table 1 under the control group. Patients are typically hospitalized for 1 to 2 days. Follow-up appointments with the surgeon take place at 1, 3 and 8 weeks after surgery.

Intervention

• Intervention 1: patients received 1200 mL of enteral tube feeding via a nasogastric tube from immediately after surgery until midday on postoperative day 1. The nasogastric tube was removed before hospital discharge on postoperative day 1, after completion of the prescribed tube feeding regimen. Patients subsequently continued a cold liquid diet orally.

• Intervention 2: patients self-administered five 125 mL oral protein drinks from immediately after surgery until midday on postoperative day 1. After completion of the prescribed protein drink regimen, patients continued a cold liquid diet orally until hospital discharge on postoperative day 1.

A detailed overview of the intervention protocol is provided in Table 1.

Sample size calculations and randomization

In a previous prospective cohort study [18], conducted at the Aalborg University Hospital, between February 1, 2015 to April 30, 2016, the standard deviation of weight loss after 8 weeks of treatment was 2.79 kg.

We used this estimate to inform the sample size calculation for the present RCT. Based on a two-sided significance level of 5% and a statistical power of 80%, the required sample size for detecting a difference between two independent means (unpaired t-test) was 45 participants per group. To accommodate potential dropouts, we increased the target to 50 participants in each group. Staff, trial managers, and patients were blinded to the randomization.

Measurement outcomes

In this study, weight was the primary measure of interest, assessed using the segmental body composition analyser (Tanita BC-418 - Tanita Co.; Tokyo, Japan). In addition, secondary body composition metrics including body mass index (BMI), basal metabolic rate (BMR), body fat percentage, fat mass (kg), fat-free mass, total body water, and visceral fat rating were collected.

Measurements were taken during scheduled hospital appointments; the presurgery examination, admission interview, and follow-up visits at week 1, 3, and 8. The assessments were performed by nurses who were specially trained in the use of the device.

Patients received written instructions explaining how the body composition analysis would be conducted, including any necessary preparations and how the results would be shared.

In addition to the body composition analysis, patient height, age, and gender were recorded.

Compliance

Data from questionnaires and hospitalization records were collected to evaluate adherence to the nutritional protocol. Postoperative adherence was measured based on the percentage of prescribed food and supplement intake before and after surgery. Preoperative adherence was calculated as the mean binary response from the survey. During hospitalization, intake was expressed as the average consumption of protein drink (Nutridrink^® Compact Protein [300 kcal/125 mL] - Nutricia A/S; Allerød, Denmark) and preoperative drink (Maltodextrin [200 kcal/400 mL] - Central Kitchen, Aalborg University Hospital) relative to prescribed amounts. For discharge day (day 1) and days 2 to 10, adherence was determined by averaging daily survey responses (0% for “no,” 50% for “partly,” 100% for “always”) and then calculating the overall mean of these daily averages.

Statistical analysis

The statistical analyses were performed using STATA version 19 (StataCorp LP; College Station, Texas, USA). Baseline continuous data were expressed as mean and standard deviations (M [SD]), whereas categorical variables were summarized as frequencies and percentages. Chi-square test was used to compare categorical data, and the one-way ANOVA test was used to compare continuous data. Compliance comparisons were made using chi-square tests and Mann-Whitney tests. Changes from baseline were analysed using mixed-effects regression models with a random intercept for each participant to account for within-subject correlation over time. Statistical significance was defined as P < 0.05 and all tests were two sided.

RESULTS

One hundred and fifty of 289 invited patients were enrolled in this randomized controlled trial (Figure 1).

One hundred and thirty-nine patients declined participation, primarily due to unwillingness to adhere to the intervention protocol. Other reasons included desire to lose weight or fear of weight gain, lack of resources or mental capacity to participate, dietary restrictions (e.g., vegan or religious), and logistical barriers such as travel distance to follow-up visits. Participants were randomly allocated into three groups. Blinding after inclusion was not feasible due to the nature of the interventions.

Baseline characteristics of the randomized population are presented in Table 2. The groups were comparable with respect to age, sex distribution, baseline weight, BMI, surgical procedure type, and body composition measures.

There was no statistically significant difference in length of hospital stay between groups, although a longer stay was observed in the control group (intervention 1: 1.2 [SD 0.6] days; intervention 2: 1.4 [SD 0.6] days; control: 2 [SD 3.3] days; P = 0.12).

Table 3 and Figure 2 show changes in body weight over time after surgery. Mean weight loss in intervention 1 at weeks 1, 3, and 8 was 2.54 kg, 3.04 kg, and 2.18 kg, respectively. Corresponding values in intervention 2 were 2.5 kg, 2.84 kg, and 2.67 kg, and in the control group 2.78 kg, 3.15 kg, and 3.03 kg, respectively. Weight loss peaked at week 3 in all groups, followed by smaller changes by week 8.

Between weeks 3 and 8, small changes in weight were observed across groups. intervention 1 showed a mean change of +0.86 kg, intervention 2 showed +0.17 kg, and the control group +0.12 kg. All groups remained below baseline weight throughout follow-up.

Compliance with the assigned interventions is shown in Table 4. Preoperative compliance, including the presurgical evening meal, protein drink, and preoperative drink, was 98% in both intervention 1 and intervention 2 (P = 1.00).

During hospitalization, compliance differed between groups, with higher values in intervention 1 (71.8 [SD 39.6] %) compared with intervention 2 (55.1 [SD 30.6] %) (P = 0.02). These measures reflect differences in intervention delivery (healthcare-administered tube feeding versus patient self-administration of oral intake) rather than directly comparable patient adherence. No statistically significant differences in compliance were observed on the day of discharge or during postoperative days 2 to 10 (P = 0.78 and P = 0.38, respectively).

In subgroup analyses of patients undergoing bimaxillary procedures, differences in weight loss were observed at week 3 across groups (P = 0.02).

At week 8, a non-significant difference was observed (P = 0.08), and no differences were observed at week 1 (P = 0.72) (Appendix 1).

No statistically significant differences in BMI were observed between groups at any time point (week 1: P = 0.81; week 3: P = 0.66; week 8: P = 0.13) (Appendix 2).

No statistically significant differences between groups were observed in fat mass, fat-free mass, body water, or visceral fat rating at any time point (Appendices 3, 4, 5 and 6). Across all groups, fat-free mass decreased more than fat mass during the postoperative period; however, no statistically significant between-group differences were observed.

DISCUSSION

This RCT aimed to determine whether systematic dietary interventions, administered pre- and postoperatively, could minimize weight loss in the first eight weeks after orthognathic surgery. Furthermore, to determine whether patients were losing fat mass, fat free mass or body water.

Our data indicate that, despite the implementation of pre- and postoperative dietary interventions, all three groups experienced only limited weight loss, and no statistically significant differences were observed between them. This finding was consistent across related body composition measures, including BMI, fat mass, fat-free mass, body water, and visceral fat rating.

The most substantial weight loss occurred within the first three weeks following surgery, followed by a gradual tapering off in subsequent weeks. Compared with existing literature, which reports postoperative weight loss of 3 to 10 kg with the majority occurring in the initial three weeks, the weight loss observed in our study is at the lower end of this range [5-8].

None of the groups returned to their baseline weight during the recovery period. In the control group, weight loss plateaued after week 3, with only a minor weight regain by week 8. Overall, the weight loss observed across all groups was relatively limited. This pattern may reflect insufficient caloric intake during recovery, with the control group showing a more consistent trajectory compared to the intervention groups, which exhibited slightly higher weight regain at week 8. Although not statistically significant, this modest regain in the intervention groups suggests a potential benefit of dietary supplementation. While our findings indicate only limited postoperative weight loss, other studies have reported that targeted perioperative nutritional support can significantly reduce early weight loss and promote faster recovery [19]. This contrast underscores the potential for more intensive nutritional interventions to further improve postoperative outcomes.

Importantly, the effect of the interventions in this study may have been underestimated due to suboptimal compliance, and it cannot be ruled out that greater adherence to the prescribed supplements might have further reduced weight loss. To understand the relationship between the interventions and the observed weight loss in orthognathic patients, it is essential to consider patients’ compliance with the assigned treatments. Both intervention 1 and intervention 2 demonstrated generally high adherence during the preoperative period, with no significant differences between groups. However, compliance notably declined during hospitalization and the postoperative period. Declining adherence to perioperative nutritional protocols has been observed in several studies; for example, postoperative compliance with oral nutritional supplements was low in a recent cross-sectional study of digestive-tract tumour patients [20].

During hospitalization, compliance was higher in intervention 1, where tube feeding was administered by nursing staff, compared to intervention 2, in which patients were responsible for drinking oral protein supplements. The passive nature of tube feeding likely reduced the burden on patients, thereby improving adherence. However, despite tube feeding being part of standard care, full compliance was not achieved. Factors such as nausea, vomiting, and discomfort associated with the nasogastric tube likely contributed to missed doses. These observations are consistent with findings by Ishikawa et al. [16], who reported that nasogastric feeding is often associated with complications, including discomfort, nausea, vomiting, aspiration pneumonia, and even asphyxiation due to misplacement of the feeding tube. Such adverse effects may reduce tolerability and ultimately affect compliance. Furthermore, our findings align with the ESPEN guideline-supported evidence that prolonged preoperative nutritional support (7 to 10 days) benefits severely undernourished patients, whereas short-term interventions - such as the brief duration of feeding tube use in our study - may have limited impact, particularly in a cohort with short hospitalisation and potentially mild or no undernutrition [21].

Tube feeding was administered by ward nurses who were not part of the project group, making it an additional task rather than an integrated responsibility. Consequently, adherence was suboptimal, for example, feeding tubes were occasionally removed prematurely. Direct oversight by the project team might have promoted stronger ownership and recognition of the intervention’s significance, provided no adverse effects occurred. This interpretation is consistent with the findings of Beck et al. [22], who identified staff non-compliance as the principal barrier to a nutrition and oral care intervention in nursing home residents. Their study highlights the importance of ensuring that staff appreciates the benefits to patients without perceiving the intervention as an added burden.

Postoperatively, compliance was lower in both intervention groups, with patients required to consume protein drinks daily as nutritional supplements. Challenges including nausea, unpleasant taste, drink consistency, and reduced appetite affected patients’ ability to follow the protocol, consistent with previous findings reported by Hammond et al. [5].

This decreased compliance, particularly in the postoperative period, may have influenced the effectiveness of the interventions and contributed to the lack of statistically significant differences in weight loss between groups. These findings highlight the importance of addressing patient experience and side effects associated with nutritional supplementation to improve adherence and potentially enhance clinical outcomes.

In this RCT, all participants - both intervention and control groups - received the same comprehensive information about the study, including why postoperative weight loss is undesirable and the rationale behind the dietary interventions. The intervention groups received dietary guidance at the presurgery examination, while the control group received similar guidance during the admission interview the day before surgery. This approach ensured that the control group had an equal opportunity to prepare nutritionally for surgery. This may explain the observed slight weight gain across all groups between the presurgery examination and admission, suggesting that timely nutritional counselling can positively influence patients’ preoperative nutritional status regardless of intervention allocation. This is in line with findings by Minnella and Carli [23], who demonstrated that even brief preoperative nutritional interventions can lead to measurable improvements in patient readiness for surgery and overall nutritional condition.

When examining the relationship between the type of orthognathic surgery and postoperative weight loss, no differences were found between the intervention groups, which is in accordance with findings from a previous prospective cohort study [18]. Patients undergoing bimaxillary surgery experience significantly greater weight loss by three weeks postsurgery compared with those who undergo single-jaw procedures. Although weight loss occurs regardless of type of orthognathic surgery, the risk and magnitude are notably higher in bimaxillary patients [18].

In this RCT, we further analysed the composition of weight loss, focusing on fat mass, fat-free mass, and body water. Our findings reveal that fat-free mass constitutes the predominant component of postoperative weight loss. This aligns with international research showing that during physiological stress caused by illness or surgery, muscle catabolism is the primary driver of weight loss. These results highlight the need for increased intake of protein-rich nutrition to mitigate muscle loss and support recovery [24].

Importantly, both single- and bimaxillary surgery patients continue to experience undesirable weight loss up to eight weeks postoperatively. However, the overall weight loss observed in this RCT was smaller than the weight loss reported in the cohort, suggesting possible improvements in perioperative care or patient management [18]. One possible explanation for this difference is the Hawthorne effect - a phenomenon where individuals alter their behaviour because they are aware of being observed or participating in a study. Participants in this RCT may have experienced behavioural changes due to the increased attention they received. For example, they may have been more motivated to maintain their weight simply because they knew they were being closely monitored. This heightened awareness could have led to reduced weight loss compared with patients in the cohort study, who were not part of a formal research setting and did not receive the same level of attention or “motivational boost.” Instead, those patients were only subject to a routine change in clinical practice, such as the introduction of regular weighing [18].

Future research should focus on optimizing the delivery, tolerability, and patient-centered design of perioperative nutritional interventions in orthognathic surgery. In particular, strategies to improve adherence, including addressing gastrointestinal side effects, taste acceptability, and treatment burden, warrant further investigation. In addition, behavioural and implementation-oriented approaches aimed at reducing compliance barriers among both patients and healthcare staff may be crucial to maximizing the effectiveness of nutritional support. Finally, studies with longer follow-up periods and more detailed assessment of functional outcomes and body composition recovery are needed to better understand the long-term clinical impact of perioperative nutritional strategies.

Limitations

This study has several limitations:

• The data collection period was relatively long, spanning from 2017 to 2022. This extended recruitment period was unavoidable due to a limited number of eligible patients between 2017 and 2021, together with delays caused by the COVID-19 pandemic. Although some of the data may therefore be considered dated, much of the existing literature in this field is based on data collected over similar periods. We therefore believe that the present study continues to provide valuable and relevant insights, particularly given the limited number of recent studies investigating postoperative nutritional interventions following orthognathic surgery.

• A total of 139 of the 289 eligible patients declined participation, most commonly due to unwillingness to adhere to the intervention protocol. Consequently, the enrolled cohort may represent patients who were more motivated to comply with postoperative nutritional recommendations than the general orthognathic surgery population. This selection may limit the generalisability of the findings, as the effectiveness of the interventions could differ in a less adherent population.

• No explicit minimal clinically important difference was predefined for postoperative weight loss or body composition outcomes. Although the sample size calculation was based on an expected between-group difference derived from previous literature and clinical judgement, the study may not have been powered to detect smaller but potentially clinically relevant differences. Consequently, while no statistically significant differences were observed between groups, the possibility of modest intervention effects cannot be excluded. This should be considered when interpreting the null findings.

• The potential influence of the Hawthorne effect should be considered. Participants in all groups may have altered their behaviour due to awareness of being observed. In addition, it was not possible to determine whether participants in the control group independently used nutritional supplements outside the study protocol, such as protein drinks purchased from external sources. These factors may have influenced adherence to the assigned interventions and should be considered when interpreting the findings. Differences in length of hospital stay between groups may also represent a potential source of residual confounding, as the control group showed greater variability in length of stay, which may reflect heterogeneity in postoperative recovery and unmeasured clinical factors.

CONCLUSIONS

In conclusion, this randomized controlled trial underscores the complexity of managing postoperative weight loss in patients undergoing orthognathic surgery. Systematic dietary interventions did not result in statistically significant reductions in postoperative weight loss or changes in body composition compared with standard care. Differences in adherence to the nutritional protocol were observed between the intervention groups, with the highest compliance in the nasogastric tube feeding group, likely reflecting that this intervention was administered by healthcare professionals rather than being self-administered. However, higher compliance was not associated with improved clinical outcomes. Furthermore, the predominance of fat-free mass loss highlights the importance of preserving lean tissue during the postoperative period, particularly following bimaxillary surgery.

APPENDIX 1 - 6

ACKNOWLEDGMENTS AND DISCLOSURE STATEMENTS

The authors would like to express their sincere gratitude to Birgitte Boel, retired registered nurse (Aalborg University Hospital, Denmark and the Department of Oral and Maxillofacial Surgery, Aalborg University Hospital, Aalborg, Denmark) for their invaluable support throughout the study. Special thanks to Lene Boelsman Henriksen (Aalborg University Hospital, Denmark and the Department of Oral and Maxillofacial Surgery, Aalborg University Hospital, Aalborg, Denmark), registered nurse for her dedicated assistance.

Funding statement

This study received support from The Danish Nutrition Council (Ernæringsrådet), which provided the enteral nutrition products and protein drinks used in the interventions.

The authors declare no conflicts of interest.

REFERENCES

1. Duarte V, Zaror C, Villanueva J, Werlinger F, Vidal C, Solé P, O Ryan JA, Requena R, Dallaserra M, Rojas R, Burgos M, Ferrer M. Changes in health-related quality of life after orthognathic surgery: a multicenter study. Clin Oral Investig. 2022 Apr;26(4):3467-3476.
   [Medline: 34854989] [PMC free article: 8637059] [doi: 10.1007/s00784-021-04315-7]
2. Al-Asfour A, Waheedi M, Koshy S. Survey of patient experiences of orthognathic surgery: health-related quality of life and satisfaction. Int J Oral Maxillofac Surg. 2018 Jun;47(6):726-731.
   [Medline: 29373200] [doi: 10.1016/j.ijom.2017.12.010]
3. Baker NJ, David S, Barnard DW, Birnie DJ, Robinson SN. Occlusal outcome in patients undergoing orthognathic surgery with internal fixation. Br J Oral Maxillofac Surg. 1999 Apr;37(2):90-3.
   [Medline: 10371307] [doi: 10.1054/bjom.1998.0432]
4. Abrahamsson C, Ekberg E, Henrikson T, Bondemark L. Alterations of temporomandibular disorders before and after orthognathic surgery: a systematic review. Angle Orthod. 2007 Jul;77(4):729-34.
   [Medline: 17605481] [doi: 10.2319/052906-215]
5. Hammond D, Williams RW, Juj K, O'Connell S, Isherwood G, Hammond N. Weight loss in orthognathic surgery:a clinical study. J Orthod. 2015 Sep;42(3):220-8.
   [Medline: 25904194] [doi: 10.1179/1465313314Y.0000000130]
6. Kendell BD, Fonseca RJ, Lee M. Postoperative nutritional supplementation for the orthognathic surgery patient.J Oral Maxillofac Surg. 1982 Apr;40(4):205-13.
   [Medline: 6951009] [doi: 10.1016/0278-2391(82)90312-3]
7. Worrall SF. Changes in weight and body composition after orthognathic surgery and jaw fractures: a comparison of miniplates and intermaxillary fixation. Br J Oral Maxillofac Surg. 1994 Oct;32(5):289-92.
   [Medline: 7999735] [doi: 10.1016/0266-4356(94)90048-5]
8. Williams RW, Travess HC, Williams AC. Patients' experiences after undergoing orthognathic surgery at NHS hospitals in the south west of England. Br J Oral Maxillofac Surg. 2004 Oct;42(5):419-31.
   [Medline: 15336767] [doi: 10.1016/j.bjoms.2004.05.008]
9. Irgebay Z, Beiriger JC, Beiriger JW, Matinrazm S, Natali M, Yi C, Smetona J, Schuster L, Goldstein JA. Review of Diet Protocols Following Orthognathic Surgery and Analysis of Postoperative Weight Loss. Cleft Palate Craniofac J.2023 Nov;60(11):1411-1418.
   [Medline: 35837697] [doi: 10.1177/10556656221113998]
10. Ooi K, Inoue N, Matsushita K, Yamaguchi H, Mikoya T, Kawashiri S, Tei K. Body Weight Loss After Orthognathic Surgery: Comparison Between Postoperative Intermaxillary Fixation with Metal Wire and Elastic Traction, Factors Related to Body Weight Loss. J Maxillofac Oral Surg. 2021 Mar;20(1):95-99.
    [Medline: 33584049] [PMC free article: 7855110] [doi: 10.1007/s12663-019-01318-6]
11. Benato L, Miotto AV, Molinari RL, Olsson B, Carlos LO, Thieme RD, Schiefecker MEM, Rebellato NLB, Scariot R, Klüppel LE. Body mass index and weight loss in patients submitted to orthognathic surgery: a prospective study. Dental Press J Orthod. 2023 Nov 10;28(5):e2323107.
    [Medline: 37970912] [PMC free article: 10637617] [doi: 10.1590/2177-6709.28.5.e2323107.oar]
12. Gasimov N, Doğruel F, Bilge S, Kazımlı İ, Demirbaş AE. Body Mass Index Changes and Muscle Loss After Orthognathic Surgery: A Prospective Study. J Oral Maxillofac Surg. 2025 Nov;83(11):1373-1380.
    [Medline: 40639420] [doi: 10.1016/j.joms.2025.06.223]
13. Dinu C, Manea A, Tomoiagă D, Băciuț M, Almășan O, Mitre AO, Barbur I, Hedeșiu M, Armencea G, Opriș H, Stoia S, Tamaș T, Băciuț G, Onișor F, Bran S. Recovery following Orthognathic Surgery Procedures-A Pilot Study. Int J Environ Res Public Health. 2022 Nov 30;19(23):16028.
    [Medline: 36498101] [PMC free article: 9737144] [doi: 10.3390/ijerph192316028]
14. Pourtaheri N, Peck CJ, Maniskas S, Park KE, Allam O, Chandler L, Smetona J, Yang J, Wilson A, Dinis J, Lopez J, Steinbacher DM. A Comprehensive Single-Center Analysis of Postoperative Nausea and Vomiting Following Orthognathic Surgery. J Craniofac Surg. 2022 Mar-Apr 01;33(2):584-587.
    [Medline: 34510064] [doi: 10.1097/SCS.0000000000008052]
15. Silva AC, O'Ryan F, Poor DB. Postoperative nausea and vomiting (PONV) after orthognathic surgery: a retrospective study and literature review. J Oral Maxillofac Surg. 2006 Sep;64(9):1385-97.
    [Medline: 16916674] [doi: 10.1016/j.joms.2006.05.024]
16. Ishikawa S, Matsumura H, Tomitsuka S, Yusa K, Sato Y, Iino M. Comparison of Complications With Semisolid Versus Liquid Diet Via Nasogastric Feeding Tube After Orthognathic Surgery. J Oral Maxillofac Surg. 2019 Feb;77(2):410.e1-410.e9.
    [Medline: 30458127] [doi: 10.1016/j.joms.2018.10.012]
17. Hopewell S, Chan AW, Collins GS, Hróbjartsson A, Moher D, Schulz KF, Tunn R, Aggarwal R, Berkwits M, Berlin JA, Bhandari N, Butcher NJ, Campbell MK, Chidebe RCW, Elbourne D, Farmer A, Fergusson DA, Golub RM, Goodman SN, Hoffmann TC, Ioannidis JPA, Kahan BC, Knowles RL, Lamb SE, Lewis S, Loder E, Offringa M, Ravaud P, Richards DP, Rockhold FW, Schriger DL, Siegfried NL, Staniszewska S, Taylor RS, Thabane L, Torgerson D, Vohra S, White IR, Boutron I. CONSORT 2025 statement: updated guideline for reporting randomised trials. BMJ. 2025 Apr 14;389:e081123.
    [Medline: 40228833] [PMC free article: 11995449] [doi: 10.1136/bmj-2024-081123]
18. Mogensen TM, Bundgaard K, Boll B, Bruun NH, Starch-Jensen T, Nielsen MG. Weight Loss Following Orthognathic Surgery: a Descriptive Prospective Cohort Study. J Oral Maxillofac Res. 2025 Mar 31;16(1):e3.
    [Medline: 40443424] [PMC free article: 12118474] [doi: 10.5037/jomr.2025.16103]
19. Prachasartta N, Siriwatana K, Trachoo V, Sapwarobol S, Chantarasinlapin P. Effects of Oral Nutritional Supplement on Postoperative Orthognathic Surgery Patients' Nutritional Status: A Randomised Clinical Trial. J Multidiscip Healthc. 2024 Dec 21;17:6059-6070.
    [Medline: 39723333] [PMC free article: 11669287] [doi: 10.2147/JMDH.S493361]
20. Su L, Zhang J, Jia L, Dou W, Li M, Zhang Y, Chang J. Compliance with oral nutritional supplements and its influencing factors in postoperative patients with digestive tract tumors: a cross-sectional study. BMC Nurs. 2024 Jun 5;23(1):380.
    [Medline: 38840132] [PMC free article: 11151578] [doi: 10.1186/s12912-024-02010-y]
21. Braga M, Ljungqvist O, Soeters P, Fearon K, Weimann A, Bozzetti F; ESPEN. ESPEN Guidelines on Parenteral Nutrition: surgery. Clin Nutr. 2009 Aug;28(4):378-86.
    [Medline: 19464088] [doi: 10.1016/j.clnu.2009.04.002]
22. Beck AM, Damkjaer K, Tetens I. Lack of compliance of staff in an intervention study with focus on nutrition, exercise and oral care among old (65+ yrs) Danish nursing home residents. Aging Clin Exp Res. 2009 Apr;21(2):143-9.
    [Medline: 19448386] [doi: 10.1007/BF03325222]
23. Minnella EM, Carli F. Prehabilitation and functional recovery for colorectal cancer patients. Eur J Surg Oncol.2018 Jul;44(7):919-926.
    [Medline: 29754828] [doi: 10.1016/j.ejso.2018.04.016]
24. Finnerty CC, Mabvuure NT, Ali A, Kozar RA, Herndon DN. The surgically induced stress response. JPEN J Parenter Enteral Nutr. 2013 Sep;37(5 Suppl):21S-9S.
    [Medline: 24009246] [PMC free article: 3920901] [doi: 10.1177/0148607113496117]