This multicenter, double-blind, 16-week RCT will be conducted from August 2019 to September 2023 in 4 clinical centers: The Second Affiliated Hospital of Yunnan University of Chinese Medicine, The Sports Trauma Specialist Hospital of Yunnan Province, Kunming Hospital of Traditional Chinese Medicine, and ShengAi Hospital of Traditional Chinese Medicine. A total of 92 eligible participants with AO will be assigned to 1 of 2 groups (catgut embedding at acupoints or nonacupoints) using central randomization (1:1 allocation ratio). Every participant will receive a 12-week intervention period and a 4-week follow-up. The flowchart of this study is shown in Figure 1.

This protocol is in line with the Declaration of Helsinki and has been approved by the Hospital Ethics Committee of The Sports Trauma Specialist Hospital of Yunnan Province (2018CK-001) in June 2018. The study has been registered in the Chinese Clinical Trial Registry (ChiCTR1800016947). This protocol is compliant with the principles of the SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials; see Multimedia Appendix 1) and CONSORT (Consolidated Standards for Reporting Trials) guidelines [44]. The SPIRIT checklist is presented in Multimedia Appendix 1 and the schedule is shown in Table 1.

Participants who meet all the following criteria will be included: (1) aged between 18 and 60 years with simple obesity; (2) BMI ≥28 kg/m² and waist circumference (WC) ≥90 cm for male participants and ≥85 cm for female participants; (3) agreed to participate in this study and signed written informed consent for this trial and catgut embedding therapy; and (4) did not participate in other trials within past 3 months. Participants will be excluded if they meet any one of the following criteria: (1) secondary obesity, such as obesity caused by endocrine disease (Cushing syndrome, thyroid disease, hypothalamic disease, pituitary disease, gonadal disease, etc) and medication (glucocorticoid or antipsychotics); (2) pregnancy, lactation, and childbirth within the past 6 months; (3) heart disease; hematopoietic system, liver, kidney, and other important organ diseases; and hypertension that is not effectively controlled; (4) severe mental and neurological diseases where the patient is unable or unwilling to cooperate; (5) allergy to alcohol and animal protein or immune diseases; and (6) received other weight loss treatment within the past 3 months.

Those who meet the following criteria should be eliminated from the study: (1) misdiagnosis and misrepresentation; (2) poor treatment tendency; (3) involvement with other treatments after being selected; and (4) participants’ withdrawal before the first test recording.

All participants with eligible AO will be recruited from the 4 hospitals and the community. Recruitment methods mainly include posters, public notice boards, and WeChat public numbers in hospitals and communities. The randomization sequence will be generated by the Clinical Research Center of Yunnan University of Chinese Medicine using a computerized random number generator and placed in opaque envelopes. Stratified randomization will be performed for the 4 clinical centers. To ensure allocation concealment, randomization will be performed by an independent researcher. The research assistant will open the envelope when the participant begins treatment to determine the assigned group and will not disclose grouping information under any circumstances. The acupuncture therapist will be responsible for manipulation only.

Participants will be informed that they have a 1 in 2 chance of being assigned to 1 of 2 treatments: catgut embedding at acupoints or nonacupoints. The procedure and stimulation of the catgut embedding at acupoints are identical to catgut embedding at nonacupoints. Therefore, participants will be blinded to their treatment assignment. Both groups of participants will be assigned to different treatment rooms to prevent intercommunication. In addition, the acupuncturist, outcome assessor, and those involved in data collection and statistics will be blinded to treatment assignment throughout the trial. Research assistants with knowledge of grouping information will be asked not to communicate with participants or outcome assessors regarding treatment procedures and responses. All patients will be fully informed about the study (including the purpose of the trial and possible risks, etc) prior to participation in the trial, and they have the right to withdraw from the trial at any time without giving a reason. They will sign a written informed consent for voluntary participation prior to enrollment.

According to the existing literature [45], the mean BMI of simple obesity was 32.30 kg/m², whereas after 12 weeks and 6 treatment of acupuncture combined with a low-energy diet, the mean BMI was 30.98 kg/m², and the improvement value was 1.32 kg/m². In contrast, the improvement value was 1.02 kg/m² in a control group with a variation from 32.74 kg/m² to 31.73 kg/m² when treated by sham acupuncture combined with a low-energy diet, and the SD of the 2 groups was 0.31 kg/m². In this project, the expected improvement value of the mean BMI of the Shu-Mu acupoints embedding group after treatment is 1.14 kg/m² and that of the nonacupoints embedding group is 0.9 kg/m², with the SD of each group being 0.31 kg/m². The significant level is ɑ=.05, and the power of a test is 1 – β = 0.95. The sample size is 84 as calculated by German G*power software 3.1 [46]. According to the 10% dropout, the total sample is 92 cases, and 46 cases will be assigned to each group.

All catgut embedding manipulations will be performed by an acupuncturist with national medical qualifications. The participants will receive treatment every 2 weeks for a total of 6 sessions.

The selection of acupoints for treatment in the ACE group will be based on the theory that obesity is closely related to the spleen, stomach, and large intestine in traditional Chinese medicine and the Shu-Mu acupoints allocation method commonly used in the current clinical treatment of obesity. The acupoint prescription includes BL20 (Pishu), BL21 (Weishu), BL25 (Dachangshu), RN12 (Zhongwan), ST25 (Tianshu), and LR13 (Zhangmen). All acupoints except Zhongwan are selected bilaterally, for a total of 11 acupoints. The locations of these acupoints are shown in Table 2 and Figure 2.

The acupoints in the control group will be selected based on the acupoints in the ACE group by moving each acupoint 2-3 cm outward horizontally in the median line (CV12 to the left side only) as a nonacupoints (not located on or overlapping with other meridians). They are labeled NA1, NA2, NA3, NA4, NA5, and NA6, respectively, for a total of 11 acupoints. The locations of these acupoints are shown in Table 3 and Figure 2, marked as red points.

The thread-embedding needle used in this study is an 8# disposable needle (Jiangxi Glance Medical Equipment Co Ltd Production), and the medical protein string is an absorbable collagen line with the specification of 2-0, 2 cm × 20 length (Jiangxi Longteng Biotechnology Co, Ltd).

The specific manipulation is as follows: participants are instructed to be placed in an appropriate position; the separate research assistant marks the acupoints or nonacupoints and routinely disinfects the skin around them; and a sterile sheet is spread, leaving only the buried area. Then, acupuncturists, who are unaware of the group allocation, take a sterile protein cord 1-2 cm long (the length depends on the location of the acupoints), place it on the front end of the trocar, connect the needle core, lift the partial skin with the thumb and forefinger of one hand, and pierce the needle with the other hand. When the piercing reaches the desired depth, apply appropriate push-and-twist techniques, push the needle core and remove the needle tube, and implant the sterile protein string in the subcutaneous tissue or muscle layer of the acupoints. After removing the needle, press the needle hole with a dry cotton ball for half a minute to stop the bleeding. Meanwhile, check that there is no thread residue exposure and no bleeding and then paste a bandage to protect the needle hole. It will be recommended that patients do not take a bath for 24 hours and keep the embedding place dry.

All data will be analyzed by SPSS statistical software (version 19.0; IBM Corp). The clinical outcomes and baseline characteristics are based on the intention-to-treat population, which will include participants who have received at least one treatment. Continuous variables will be shown as the mean and SD, whereas the nonnormally distributed variables will be presented as the median and IQR. Categorical variables will be described as numbers and percentages. The normality of continuous variables will be determined using the Shapiro-Wilk test, Kolmogorov-Smirnov test, skewness, and kurtosis. The homogeneity of continuous variables will be determined by F-test, Brown-Forsythe, and Bartlett tests. Comparisons between groups will be made using independent samples 2-tailed t tests or nonparametric tests (Mann-Whitney U test). Repeated measures within groups (≥3) will be analyzed using one-way ANOVA or nonparametric (Friedman) tests. Paired 2-tailed t tests or nonparametric tests (Wilcoxon test) will be used for within-group pre-post comparisons. For categorical data, the chi-square test will be used to assess the significance of differences. Values of P<.05 will be considered significant using a 2-sided test.

In the past, obesity was considered a problem in high-income countries. However, recent studies reported that the prevalence of obesity is rapidly increasing in low- and middle-income countries [4,48-50]. As a type of obesity, AO is also related to cardiovascular diseases, cancer, and many other diseases [51-54].

ACE is a traditional Chinese medical practice that has been used in clinical practice since the mid-1960s. Compared with other treatments, ACE has the advantages of a short single-treatment time, long effective stimulation time, low impact on daily life, as well as being time-saving and low cost and having few side effects, which are well suited for the fast-paced modern society and become gradually favorable to patients who are obese. As a specific type of acupuncture therapy, ACE has gained substantial attention in the management of obesity in recent years. Research has demonstrated that ACE has a certain impact on obesity. First, it can reduce BW by regulating appetite and food intake. ACE stimulates specific acupoints, promoting the release of neurotransmitters and hormones to regulate feelings of hunger and satiety and ultimately reducing food intake [55]. Second, ACE can improve metabolic function. Studies have shown that acupoint stimulation can affect various physiological processes, including the endocrine, nervous, and immune systems, thus regulating energy and fat metabolism, improving insulin sensitivity, and enhancing blood lipid levels [41]. Additionally, ACE may also have positive effects on obesity by improving psychological well-being and sleep quality, among other factors [56]. However, current research has some limitations, including small sample sizes and inconsistent study designs [57]. Therefore, to better assess the effectiveness and safety of ACE treatment, further high-quality studies with larger sample sizes are needed.

The decrease of several indicators such as BW, WC, BMI, HC, and appetite is not only beneficial to personal health but also helps people who are obese to reshape their bodies [58]. Among them, BMI is the most commonly used indicator in obesity research, but it mainly reflects total body fat and cannot distinguish between fatty obesity and muscular obesity. HC is affected by both sex and age, and changes in abdominal fat cannot be accurately reflected promptly [59]. WC can directly reflect abdominal fat, so we use WC as the main outcome indicator and other related indicators as secondary outcome indicators. According to the classification adopted by the Chinese Medical Association of China in 2019, the inclusion criteria was set as WC ≥90 cm for male individuals and ≥85 cm for female individuals, rather than those of other Asian countries (WC ≥102 cm for male individuals and WC ≥88 cm for female individuals or WC ≥ 90cm for both male and female individuals) [6,60].

The combination of Shu and Mu acupoints is one of the classical methods of acupuncture and is mainly used in clinical practice to treat metabolic diseases of the viscera. According to the identification theory of traditional Chinese medicine, obesity is mainly caused by the dysfunction of the spleen, stomach, and large intestine, so we chose the Shu and Mu acupoints of these 3 internal organs as the treatment prescription. Our preliminary analysis of 175 obesity ACEs in the early stage also found that the existing high-frequency acupoints for obesity ACEs were mainly Shu and Mu acupoints of the spleen, stomach, and large intestine [61].

First, this study is a multicenter RCT designed to investigate the efficacy and safety of ACE in AO with a relatively long study period, and the results will provide powerful evidence for the clinical application of ACE in the treatment of obesity. Second, participants’ diet and exercise will not be intervened, which will allow participants to maintain their original lifestyle habits throughout and maximize the efficacy of ACE. Finally, to maintain the success of the double-blind method, contact between participants from different groups will be avoided. The acupuncturist, data evaluator, and statistician will also be hidden from the group assignment, which will minimize possible bias in the results.

Limitations of this study are as follows. First, the relatively short follow-up period of this study may not be comprehensive enough to assess the durability of ACE efficacy. Second, the selection of nonacupuncture acupoints as an intervention in the control group in this study may inevitably produce some efficacy as well [62,63]. Third, only patients with AO are selected as the study population in this study, and further studies on different types of obesity will be conducted at a later stage.

In summary, our trial aims to investigate the difference in the effectiveness of catgut embedding at acupoints and catgut embedding at nonacupoints in patients with AO. This finding will provide reliable evidence to support whether ACE is an effective and safe treatment for AO.