Abstract
The increasing prevalence of obesity worldwide has led to a surge in the demand for effective weight management strategies. While lifestyle modifications remain the cornerstone of obesity management, dietary supplements and anti-obesity medications (AOMs) have gained considerable attention. This article examines the effectiveness and safety of various Japanese diet pills, including both traditional herbal medicines and pharmaceutical interventions, while making maximum use of the information provided by the user.
Introduction
Obesity, characterized by abnormal or excessive body fat accumulation, presents a significant global health challenge. The World Health Organization defines obesity as a body mass index (BMI) of ≥ 30 kg/m2 among adults. However, racial variations exist, with Asians typically having a lower BMI but a higher risk of obesity-related comorbidities. Consequently, lower BMI thresholds are often used to define obesity in Asian populations.
The prevalence of obesity has increased dramatically worldwide, tripling between 1975 and 2016. Several studies report an increase in obesity in Japan, with a higher prevalence among men than women. Obesity is a well-established risk factor for chronic noncommunicable diseases, including cardiovascular disease (CVD) and type 2 diabetes (T2D). The East Asian population tends to accumulate more visceral fat at lower BMI levels, making them more susceptible to obesity-related comorbidities.
Anti-Obesity Medications (AOMs) in Japan
Despite the clinical and public health impacts of obesity in East Asian populations, the availability of anti-obesity medications (AOMs) differs between countries. In Japan, the Japan Society for the Study of Obesity (JASSO) recommends diet, exercise, and behavioral therapies before initiating pharmacotherapy for obesity disease. Pharmacotherapy using AOMs is suggested for nonresponsive obesity disease and severe obesity disease. However, few AOMs are available in Japan.
Mazindol
Mazindol is an anorexiant available for short-term weight loss among patients with severe obesity disease. It acts on the feeding center of the hypothalamus and inhibits monoamine re-uptake, leading to suppression of appetite and food intake.
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A multicenter, double-blind study in Japan assessed the safety and efficacy of mazindol versus placebo among PwOD. Patients randomly received a 0.5-mg mazindol tablet or an inert placebo for 12 weeks based on a fixed-flexible dosage schedule, with the final mean dose of mazindol of 2.11 mg.
Semaglutide
Subcutaneous semaglutide 2.4 mg, a glucagon-like peptide-1 receptor agonist (GLP-1RA), is the first medication to be approved for weight management by the Pharmaceuticals and Medical Devices Agency in Japan since mazindol. Glucagon-like peptide-1 (GLP-1), an incretin hormone, induces glucose-dependent secretion of insulin, thereby inhibiting glucagon production and suppressing hepatic gluconeogenesis. Additionally, it also leads to a delay in gastric emptying and a reduction in appetite (by acting on the hypothalamus) and energy intake.
The STEP 6 trial conducted by Kadowaki et al. was a double-blind, phase IIIa post hoc analysis that investigated the effect of semaglutide for weight management among adult East Asian (South Korea and Japan) PwOD with or without T2D. Patients were randomized (4:1:2:1) to receive either once-weekly subcutaneous semaglutide 2.4 mg or a matching placebo, or semaglutide 1.7 mg or a matching placebo, for 68 weeks (via a dose-escalation regimen), along with lifestyle intervention for D&E. Oral hypoglycemic medications were in concomitant use among patients at baseline.
Dietary Supplements in the Japanese Market
Numerous supplements are marketed in Japan for their anti-overweight properties, but most lack proper evidence. Evidence-based research regarding the efficacy and safety of anti-obesity supplements is required to make definite recommendations for lifestyle management. This section reviews ingredients for which evidence is available.
Ashitaba
Ashitaba is a green and yellow vegetable of the Apiaceae Angelica family. Zhang et al. (2013) demonstrated that ashitaba contains the two main phytochemicals 4-hydroxyderricin (4HD) and xanthoangelol (XAG), which have various biological effects that lead to anti-tumor, anti-inflammatory, and anti-diabetic activities. Ohnogi. et al. (2012) reported that ingestion of ashitaba green juice (6.2 g/day) for 8 wks resulted in significant reduction in visceral fat areas (−25.5 cm2, p < 0.01), body weight (−1.4 kg, p < 0.05), BMI (−0.5, p < 0.05), and body fat (−2.1%, p< 0.01) in nine adult subjects with metabolic syndrome.
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Bofu-tsusho-san (BF)
Bofu-tsusho-san (BF), a traditional Japanese herbal medicine “kampo” comprising 18 crude components, has been an effective treatment for obesity, constipation, and hypertension. Hioki et al. (2004) conducted the randomized, double-blind, placebo-controlled study of BF. Eighty-one obese Japanese women (BMI 36.5 ± 4.8 kg/m2) with IGT and IR were randomized to receive either placebo (n = 40) or BF (24 mg/day) treatments (n = 41). After 24 wks, the BF group had significantly reduced bodyweight (90.8 ± 17.9 to 80 ± 10.3, p < 0.01) and abdominal visceral fat (197.6 ± 69.7 to 104.4 ± 28.0, p < 0.01), without decreases in resting metabolic rates (1986.2 ± 402.5 to 1821 ± 420.6).
Capsinoids
Capsinoids are abundant in non-pungent chili peppers. Yoneshiro et al. (2013) conducted a 6wk, placebo-controlled study and reported that cold-induced thermogenesis (CIT) was increased after administration of capsinoids (9 mg/day) (200.0 ± 33.9 vs 81.0 ± 32.5 kcal/d). Snitker et al. (2009) conducted a 12-wk, placebo-controlled, double-blind, randomized study in which 80 subjects (BMI 30.4 ± 2.4) were recruited and randomly assigned to capsinoid (6 mg/day) or placebo treatment groups. Capsinoids were well tolerated and mean ± SD weight changes of 0.9 ± 3.1 and 0.5 ± 2.4 kg were observed in capsinoid and placebo groups, respectively (p = 0.86).
EPA and DHA
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are essential omega-3 fatty acids found in cold-water fish. Hill et al. (2007) recruited 75 overweight volunteers (BMI > 25) and investigated the effects of fish oil intake and regular exercise. After the 12-wks intervention, FO supplementation lowered triacylglycerols, increased high density lipoprotein cholesterol (HDL), and improved endothelium-dependent arterial vasodilation (p < 0.05). Both fish oil and exercise independently reduced body fat compared with baseline measurements (p < 0.05).
Coleus forskohlii (CF)
Coleus forskohlii (CF) is a native Indian coleus plant of the Lamiaceae family. Kamohara et al. (2013) performed an 8-wk open-label study of 15 healthy volunteers, who received 1000 mg of CF extract/d (10% forskolin).
Hydroxycitric Acid
Hydroxycitric acid is an anti-obesity active ingredient found in rinds from the Indian fruit Garcinia cambogia (GC). Hayamizu (2003) et al. performed a double-blind, randomized, placebo-controlled, parallel-group design trial of 44 subjects (GC, n = 18; placebo, n = 21) aged 20-65 years with visceral fat areas of >90 cm2. Subjects were randomly assigned to receive GC extract for 12 wks (1667.25 mg/9 tablets, containing 1000 mg of hydroxycitric acid). At 16 wk, the GC group had significantly reduced visceral, subcutaneous and total fat areas compared with placebo group (p < 0.001).
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Lactoferrin (LF)
Lactoferrin (LF) is an iron-binding glycoprotein found in exocrine secretions. Ono et al. (2010) performed a double-blind, placebo-controlled design study of 22-60-year-old Japanese men and women (n = 26) with abdominal obesity (BMI > 25 kg/m2 and visceral fat area > 100 cm2). Subjects consumed enteric-coated LF (eLF) (300 mg/d as bovine LF) or placebo tablets for 8 wks. In comparison with the placebo group, visceral fat area was significantly reduced in the eLF group (−1.8 vs. −14.6 cm2, respectively, p = 0.009; ANCOVA). Decreases in body weight, BMI, and hip circumference in the eLF group (−1.5 kg, −0.6 kg/m2, and −2.6 cm, respectively) were also significantly greater than those in placebo group (1.0 kg, 0.3 kg/m2, and −0.2 cm; p = 0.032, 0.013, and 0.041, respectively).
L-Carnitine (LC)
L-Carnitine (LC) is a vitamin-like amino acid derivative involved in metabolism of lipid and use of fat energy. Wutzke et al. (2004) showed that oral administration of LC to healthy human subjects for 10 days significantly facilitated fatty acid oxidation, indicating that LC may be a limiting factor for fat catabolism.
Glucomannan
Kim et al. evaluated the safety and efficacy of glucomannan, a water-soluble fiber supplement, for achieving weight loss in overweight and moderately obese individuals consuming self-selected diets. Participants were randomly assigned to take 1.33 grams of glucomannan or identically looking placebo capsules with 236.6 mL (8 ounces) of water one hour before breakfast, lunch, and dinner for 8 weeks. At 8 weeks, there was no significant difference between the glucomannan and placebo groups in amount of weight loss (−.40 ± .06 and −.43 ± .07, resp.) or other efficacy outcomes or in any of the safety outcomes.