Although acupuncture is being utilized to treat a variety of important health problems, its usefulness in obesity management has not yet been fully evaluated. The aim of this review paper was to survey and critically evaluate the descriptive and controlled trials of acupuncture for enhancing weight loss. The underlying principles of acupoint stimulation are described, with an emphasis on auricular (ear) acupuncture, the method most often chosen for obesity studies. The difficulties of selecting suitable placebo controls are highlighted. To date, most trials have been descriptive in nature, of short duration (≤12 weeks), and designed using nonstandard treatment protocols. Despite the unique challenges involved, further careful study of acupuncture's potential usefulness as an adjunct in weight management is recommended. An agenda for future research in this area is provided.
Introduction and overview
The problem of obesity
Obesity is a serious, prevalent, and refractory problem.1 Individuals who are overweight (BMI >25 kg/m2) or obese (BMI >30 kg/m2) are at greater risk for a variety of medical conditions including diabetes, hypertension, dyslipidemia, cardiovascular disease, and sleep apnea.2 The psychological consequences are also severe and include body image disparagement, impaired quality of life and, among the severely obese, depression.3,4,5
The CDC recently reported that 34% of Americans are overweight and 27% are obese.6 Worldwide, it is estimated that 7% of adults are obese, but two to three times as many are considered overweight.7 The prevalence of obesity in established market economies (Europe, Canada, Australia, etc) is estimated to be 15–20%.8 In developing countries, the proportion of overweight in preschool children was found to be increasing in 16 of 38 countries.9 A consistent finding of behavioral treatments is that one-third of the weight lost is regained 1 y after treatment, two-third after 2–3 y and full weight is regained at 5 y.10,11 A myriad of factors may make efforts to control weight difficult, including unrealistic expectations,12 genetic predisposition,13 an environment that promotes increased energy intake, and decreased physical activity.14
Complementary and alternative approaches
The serious, widespread and refractory nature of obesity makes it ripe for investigations of complementary and alternative approaches.15,16 Two broad types of approaches have been suggested. One is a complete abandonment of the dieting paradigm, often referred to as ‘undieting’ or ‘nondieting.’17 This movement contends that dieting is not only ineffective, it is harmful.18,19,20 This approach has not been well studied, but seems to produce favorable psychological changes (body image, depression, and self-esteem) without producing weight loss.21
Another broad class of complementary and/or alternative approaches has not abandoned the basic fundamentals of dieting (ie, decreasing intake) but has either decreased the intake of targeted foods (ie, reducing carbohydrates rather than total calories) or has combined traditional dieting methods with herbs, supplements or nontraditional methods such as acupuncture. Freedman et al22 have summarized the findings for low-fat and low-carbohydrate diets, and Allison et al23 have reviewed the use of herbs and supplements in the treatment of obesity. However, little comprehensive information has been published relating to acupuncture in the treatment of obesity.
The focus of this review will be on acupuncture as a treatment for obesity. This paper will provide: (1) a brief overview of the methods and mechanisms of acupuncture; (2) a summary of descriptive and controlled studies of acupuncture in the treatment of obesity; and (3) an agenda for future research.
Mechanisms and methods of acupuncture
Acupuncture, practiced for several thousand years in China,24 is increasingly used worldwide in the treatment of many disorders. An accumulating body of evidence summarized in a NIH Consensus Statement on Acupuncture25 confirms that acupuncture treatment has beneficial effects for conditions ranging from postoperative dental pain to chemotherapy-associated emesis. It is also effective as an adjunctive modality for joint and muscle pain, addictions, and asthma.
Meridians and acupoints
In Traditional Chinese Medicine (TCM), life force or ‘Qi’ (‘chee’) is thought to circulate within energy pathways or ‘meridians’ longitudinally throughout the body. There are 14 major meridians, corresponding (loosely) to the Western definition of ‘organs.’ Acupuncture points are specific locations on the body considered to be connected to these energy meridians.25,26,27 During illness Qi is thought to be out of balance, and stimulation of acupuncture points corrects this imbalance. Theoretically, an ‘excess’ or ‘deficiency’ of Qi can be ‘normalized’ by the specific manner of point stimulation.
Using this paradigm, obesity and/or excess appetite has been conceptualized in a variety of ways, such as ‘heat’ in the stomach and intestine,28 a deficiency of Qi in the spleen and stomach,28,29 or a deficiency of primary Qi.28 Based on these beliefs about the causes of obesity, a variety of acupoints are targeted in the treatment of obesity, including: Neiguan (P 6), Fenglong (St 40), Liangmen (St 21), Guanyuan (R 4), Zusanli (St 36), Tianshu (St 25), Quchi (LI 11), where P refers to a lung point, St to stomach, R to kidney, and LI to large intestine.30
In terms of traditional medicine, it is believed that acupuncture works to alter central nervous system neurotransmitter levels by stimulating peripheral nerves at acupoints. These stimulated nerves then carry the signals centrally,31,32 shown in Figure 1, including to the spinal cord, pituitary, and midbrain. Activated centers can then release neurochemicals: endorphins, monoamines, and cortisol.31
A large number of acupuncture points (365 points have been identified in Chinese acupuncture maps) show concentrations of peripheral nerve junctions, referred to as ‘trigger points’.26 A variety of methods are used to stimulate acupoints.25,31,33 These include:
Needling or ‘traditional acupuncture’, in which fine stainless-steel needles are inserted through the skin to various depths, kept in place for varying lengths of time and/or further stimulated manually or electrically (‘electroacupuncture’).
Press needles or ‘staplepuncture’ in which short acupuncture needles are taped into place for extended periods with pressure being applied on a regular basis.
‘Acupressure’ in which beads are massaged or pressed at specific locations.
‘Moxibustion’ involving the application of heat, by burning small grain-sized pellets of combustible material on or near the acupoints.
‘Cupping’ or using cups of various materials to create ‘negative pressure’ or a vacuum on the skin surface for increased blood circulation and point stimulation.
Transcutaneous electrical nerve stimulation (‘TENS’) which involves applying electrode pads to the skin surface which transmit a mild current into the acupoint.
Auricular (ear) acupuncture is the method most often used for the treatment of obesity.29 Common auricular points used in the treatment of obesity include ‘Hunger’ and ‘Stomach’ points (for satiety and fullness) and ‘Shenmen’ (for sedation and analgesia)34,35,36,37,38 (Figure 2). The external ear (auricle) is innervated by several nerves, including vagus, glossopharyngeus, trigeminus, facialis, and branches (the second and third) of the cervical spinal nerves.29 The vagus nerve is thought to interact with cranial nerves and those of the digestive tract, as these nerves share a common path to the brain.39 It is hypothesized that stimulation of the auricular nerve causes interference to appetite signals from the gastrointestinal tract40 (see Figure 3).
Satiety, hunger, and appetite
Rat studies suggest that stimulation of the auricular regions—associated with the ventromedial hypothalamus—affects the satiety center and leads to improved weight loss (or reduced gain) in both obese and nonobese rats.41,42,43 Likewise, there have been anecdotal reports of reduced appetite and cravings from patients wearing auricular acupuncture devices (press needles, staples, or beads).40
By increasing the release of neurotransmitters,44,45,46 acupuncture may improve mood, which, in turn, might lead to improved regulation of food intake. Alternatively, acupuncture may suppress appetite by endorphin-induced decreases in stress and depression.47,48 The positive effects of standard acupuncture49 and electroacupuncture50 on mood have been observed in treating clinical depression. Given the relation between medications that are thought to alter serotonin levels and improved mood and weight loss,51 acupuncture may exert an effect by increasing serotonin levels.
Results of clinical trials with acupuncture
Most studies of acupuncture in the treatment of obesity have been descriptive in nature with little systematic reporting or analysis of data.52,53,54 In general, the reports from China appear to be positive with regard to the use of acupuncture for weight loss,55,56 reduction of cardiovascular risk factors57 and parameters of carbohydrate metabolism (lower insulin and improved glucose control).58 Both within and between studies, lack of standardization in the points treated and variability in the length and frequency of treatments further compromise the utility of these studies.
Beginning in the 1970s, several US studies examined the use of acupuncture alone for the treatment of obesity. Sacks54 performed a retrospective chart review of individuals treated for drug addiction, obesity, alcoholism, and excessive smoking using ear staplepuncture, plus additional acupuncture needling at a variety of body points. Among 1030 cases of obesity—treated for varying lengths of time—presented only as ‘success rates’, 25% showed excellent success, that is, weight loss of 8–10 lb/month, 50% good success (control of the eating habits and half of their individually set goal reached), while 20% were ‘not influenced at all’.
Soong59 studied 21 obese patients using various auricular points for treatment periods ranging from 2–6 weeks and reported a mean weight loss range of 3.3±1.9 kg with a range of 1–7.3 kg. All patients reported anecdotal decreases in appetite, but the data were not summarized or analyzed. Dung53 treated 36 overweight individuals (27 females, nine males) using acupuncture ‘press’ needles (two needles in both ears) for 2 weeks at a time, with a 7–10 day rest period prior to the next cycle. Although few people returned for a second series of needle placements, 39% (14 of 36 patients) had lost ≥4 lb (range: –4 to –12 lb) in a 3-week period. The author concluded that the study results where ‘not very promising’, although the weight loss for the group as a whole (reported as a list but not analyzed) was indeed statistically significant (P<0.001).
More recently, Huang et al34 evaluated weekly auricular acupuncture in combination with individualized dietary and aerobic exercise recommendations (so-called ‘triple therapy’) among 45 adult obese patients (8 males, 37 females). After 8 weeks, effectiveness was rated at 87% (ie, body weight and body fat reduced by at least 2 kg and 1%, respectively). The lack of a control group makes it difficult to separate the effects of diet and exercise from those of acupuncture.
There are seven comparison studies of acupuncture in the treatment of obesity (Table 1). Among these seven, one has only been reported in abstract form,60 another as a conference proceeding,37 and another did not use random assignment.61
In a nonrandomized study of 120 participants (initial weight not specified), Giller61 reported that ear acupuncture press needles applied for 6 weeks resulted in ‘hunger reduction’ and weight loss (over 2 lb/week for at least 4 weeks) in 70% of patients who had been treated at the ‘hunger point’. Among participants treated at ‘stomach,’ ‘lung’, or a ‘placebo’ ear point, only 20% reportedly lost weight. However, no quantitative data were presented in this report and the treatment was not consistent for all participants (eg, placement of needles was changed every 2 weeks if there had been no effect).
Sun and Xu62 used a standardized treatment of auricular acupressure + body acupuncture over a 90-day period in 110 subjects compared to 51 controls (randomized 2 to 1). Those in the control group received only an herbal supplement, Oenothera erythrosepala, evening primrose oil (1500 mg twice a day), which is high in γ-linolenic acid. The treated group had significantly greater reductions in weight (5.0±2.3 vs 2.1±1.6 kg; P<0.01) and body fat percentage (3.0±1.6 vs 1.5±1.0%; P<0.01). Similarly, in an 8-week clinical trial of 14 obese women in Austria, individuals receiving diet+acupuncture (point placement not described) lost more than twice as much weight than diet-only controls (7.7±4.4 vs 3.6±2.2 kg; P<0.005).60
Shafshak36 found that auricular electroacupuncture, administered five times a week for 3 weeks combined with a 1000-kcal/day diet, was associated with greater weight loss success (P<0.05) for the obese women treated at the ‘hunger’ (n=10) and ‘stomach’ (n=10) ear points, compared to those treated at a placebo (n=10) point. Specifically, among patients treated at the ‘hunger’ and ‘stomach’ points, 7 of 10 individuals lost 1–4 kg compared to 2 of 10 individuals in the placebo group. In this study, treating the stomach point appeared to be effective, in contrast to the results of Giller61 described above.
Steiner et al37 randomized 78 subjects into four groups: real acupuncture (body and ear points), sham acupuncture (points near those used in real acupuncture group, but electrically inactive), behavior modification only (weekly classes on nutrition and behavior management), and wait-list controls. Data from 57 subjects after 8 weeks showed that absolute and percent weight losses in the real acupuncture group (−2.7 kg; 3.3%) were comparable to those achieved with behavior modification (−4.2 kg; 3.6%) and greater than both the ‘placebo-acupuncture’ (−1.2 kg; 1.2%) and wait-list control groups (+0.5 kg; 0.3% weight gain). The weight loss of both the real acupuncture and behavior modification groups differed significantly from the wait-listed controls (P<0.05).
Two studies have found no effect for acupuncture. Following 3 months of weekly auricular acupuncture plus moxibustion or placebo ‘minimal acupuncture’ (superficial needling and lateral to the treatment points), Mazzoni et al35 reported no differences in weight change in 40 subjects and no significant between-group changes in BMI. High and differential attrition between groups (30% in the treatment group and 60% in controls) makes this study difficult to interpret. Mok et al63 used a 3 × 3 factorial design in 24 overweight adults to test press needles in the ear at three separate periods at three different locations (one being a ‘placebo point’). None of the groups had a significant change in weight.
Several studies have examined less invasive acupuncture-related methods for weight control. Allison et al64 evaluated the efficacy of an auricular acupressure device (‘Acu-Stop 2000’) using a randomized, controlled design in 69 subjects, all of whom received nutrition education. Treatment subjects were instructed to massage the ear with the device for a few minutes at specific times throughout the day; controls applied the device to their wrists. After 12 weeks of treatment, weight loss did not differ between groups.
Richards and Marley38 assessed the efficacy of a portable, noninvasive TENS device (AcuSlim) in a 4-week randomized clinical trial of 60 subjects. In total, 95% of respondents in the treatment group, who applied the TENS to two ear points, reported appetite suppression (self-reports), compared to none of the controls, who administered the device to their thumb. None in the control group lost ≥2 kg, compared to 79% in the treatment group. Among individuals who lost weight (four controls and 26 treated subjects), the average weight loss was 0.6±0.3 kg in the control group vs 4.0±1.4 kg (P<0.05) in the treatment group.
Unique methodological problems in acupuncture research
Acupuncture has several intrinsic challenges that are unique to its methodology: nonstandardized or individualized techniques, appropriate controls, and safety concerns.
In traditional Chinese medicine (TCM), treatment plans and acupuncture points are highly individualized, based on the location and the deficiency/excess of Qi.57,65 Accordingly, different set of points would be used, depending on which organ(s) needed to be ‘energized’ or ‘inhibited’.62 Furthermore, acupuncture needles can be ‘twirled’, electrically stimulated, and left in place for variable lengths of time. There are several variations of acupuncture (eg, Japanese, French, Korean, Traditional Chinese, and English) with corresponding differences in needle penetration depth and duration, treatment focus and point selection.25,33 This lack of standardization makes both the design and interpretation of studies difficult.
Methodological problems66 in obesity-related acupuncture trials include difficulties in the blinding process, finding an appropriate placebo or control mechanism, and patient expectations of acupuncture's efficacy influencing perceived or actual outcome.67 Concealing allocation of treatment vs control is uniquely challenging.68 When a nonacupuncture point (‘sham’) is used, it is possible for the treatment to be blinded by all except the acupuncturist, since a needle is applied to the same depth and for the same duration as the treatment group but in a location that has no known effect. Nevertheless, there have been studies showing that up to 50% of individuals treated by such ‘sham’ processes show some physiological effect, especially in studies of pain inhibition.66 More recent placebo acupuncture has utilized ‘minimal acupuncture’, needling very near the treatment point, but only to a shallow depth (1–2 mm) and with only slight stimulation.66 In addition a promising, new placebo needle has been designed with a nonpenetrating, blunt tip, held in place by a bandaid and plastic ring.69 This placebo needle was shown to be perceived by volunteers as similar to the true penetrating acupuncture needle (also held in place via bandaid and ring),69 and, appropriately, the placebo was significantly less effective in reducing tendinitis pain and discomfort.70
With or without appropriate blinding and placebo controls, expectations about the credibility (usefulness and efficacy) of unconventional methods such as acupuncture may influence outcome.71 Such moderating variables may obscure real differences between groups especially in small samples. One suggested mechanism to control for patients’ expectations is the treatment credibility assessment,66,67,72 adapted from Borkovec and Nau,72 which is a simple series of four questions designed to measure the individual's belief in the efficacy of treatment. Ideally, the mean scale scores should be equivalent for both treatment and control groups.
Safety issues in acupuncture
Acupuncture needles can cause local pain, inflammation, or occasional infection,73,74,75,76,77,78 particularly if left in place for extended period.73,75,76,79 Yamashita et al80 prospectively evaluated 55 291 acupuncture treatments administered by acupuncturists with medical training and documented only 64 adverse events (0.12%). All of these adverse events were minor, the most common being bruising, dizziness, perspiration, discomfort, and dermatitis. More serious complications such as infection, cardiac tamponade, spinal lesions, and pneumothorax have been reported in the literature,78,79,81 though none were observed by Yamashita et al.80 Among a sample of 1332 practitioners in Norway (1135 doctors and 197 acupuncturists), the average rate of complications was determined to be only 0.21 complications per year for every year of (full-time) acupuncture practice.74
Adequate placebo controls
Standardized controls should be used in all future clinical trials of acupuncture treatment in obesity. Minimal acupuncture66 and the more recently developed placebo needle69 may be more appropriate methods to ensure validity in assessing the effectiveness of acupuncture. Credibility assessment would also help to ensure that the groups are comparable.67,72
To assess accurately any potential benefits for treating obesity, the art of acupuncture must be effectively bridged with the science of evaluation. Standard algorithms need to be developed, based on principles used by practitioners, for example, criteria for selecting and changing point locations, and spacing of treatments.
Evaluate as a complementary treatment
Several randomized controlled trials have suggested that acupuncture has a positive impact on short-term weight loss. These positive effects are typically not observed when acupuncture is used in the absence of dietary and/or behavioral interventions. Therefore, future studies should include a behavioral component across conditions in order to maximize success, provide an active treatment for the controls, and decrease attrition in the comparison groups.
Most of the studies to date have been of short duration, ranging from 361 to (only one study lasting) 24 weeks,60 with most lasting only 12 weeks.35,62,63 As a chronic condition, obesity is likely to require longer periods of acupuncture treatment. Acupuncture may also be considered during the maintenance phase of weight loss programs to maximize relapse prevention. In addition, attrition data at each phase of treatment would provide a more thorough evaluation of this alternative treatment.68
Most of the literature on acupuncture for the treatment of obesity is based on uncontrolled trials. Among the few controlled trials with positive results, the effects are modest, and the interpretation of these results is limited by those factors already mentioned, such as short duration, inadequate placebo controls, and nonstandard treatment protocols. In light of the evidence, we believe acupuncture is a potentially useful adjunct in weight management that deserves more careful study.
About this article
International Journal of Obesity (2009)