By Sophya Yeoh
In an age of convenience where almost anything can be procured almost immediately, it is no wonder why many try to apply this approach to weight loss. This is further fuelled by the societal pressure to have an “ideal” body shape that is plastered all over social media, while most live a relatively sedentary lifestyle. Despite the common knowledge that weight loss is achieved by making lifestyle modifications – physical exercise, healthier diet, and good eating patterns – adherence to conventional weight loss programmes are infamously low as results are not instantaneous and commitment to drastic changes are difficult (Pittler and Ernst, 2004). As such, many turn to self-proclaimed non-prescription dietary supplements which come in many forms such as tablets, pills, powders, liquids, and bars (National Institutes of Health, 2020). In 2014, at least 60% of the adult population of USA alone had reported use of weight loss supplements (WLS), mostly in women (Dickinson and MacKay, 2014). The industry has grown since then, being estimated to be valued at USD 4.5 billion in 2019 and projected to reach USD 5.88 billion by 2024 (Technavio, 2020).
WLS are categorised as food products as they are usually “herbal” in nature and are not subjected to strict regulation unlike allopathic medicine, making them widely available without prescription (Mohamed Ansari and Omar, 2017). Dishonest producers have taken advantage of this to sell fraudulent products or supplements containing undeclared drug ingredients (National Institutes of Health, 2020). Only if these are found to be unsafe and harmful after being sold will regulatory bodies be able to remove them from the market (National Institutes of Health, 2020). WLS are often manufactured to contain the “ultimate blend” of ingredients to combat fat and low metabolism that are said to be “natural” to target scepticism of artificial products. Consumers are then less likely to inform their doctors of their intake of these products, which could potentially be toxic to the patient if the supplements interact with prescription medication – especially for patients with chronic disease (Mohamed Ansari and Omar, 2017).
Hydroxycitric acid (HCA) obtained from extracts of the tropical fruit Garcinia cambogia is one of the most common ingredients found in WLS (Alraei, 2010; Semwal, Semwal, Vermaak and Viljoen, 2015; National Institutes of Health, 2020). HCA has been shown to inhibit lipogenesis by inhibiting citrate cleavage enzyme and which catalyses the first step, and is proposed to suppress appetite to reduce food intake (Heber, 2003; Alraei, 2010). In a meta-analysis by Pittler and Ernst (2004), they concluded that some studies did show greater weight-loss in treatment groups, although many others reported discordant results. Adverse effects have also been observed in the studies, ranging from mild headaches, nausea, and gastrointestinal symptoms, to severe cases of hepatoxicity and mania (Alraei, 2010; Semwal, Semwal, Vermaak and Viljoen, 2015) Overall, there is no profound evidence to support its ability to aid weight loss, and its safety and efficacy remains to be proven in large-scale and long-term trials as most existing studies have only investigated HCA/Garcinia cambogia-containing supplements for a short time period.
Another widely popular ingredient in WLS is conjugated linoleic acid (CLA), a mixture of linoleic acid isomers with conjugated double-bonds found mainly in meat and dairy products (Alraei, 2010; National Institutes of Health, 2020). CLA can alter body composition and energetic metabolism by putatively increasing lipolysis, reducing lipogenesis, and oxidising fatty acids (Lehnen et al., 2015; National Institutes of Health, 2020). Multiple animal studies have shown CLA to reduce fat mass, but human experiments have only been able to replicate their success with middling results and often less significantly (Lehnen et al., 2015, National Institutes of Health, 2020). Negative effects of CLA consumption have been recorded, including mice developing pro-carcinogenic properties, increasing oxidative stress, promoting resistance to insulin, gastrointestinal irritation (diarrhoea, vomiting, abdominal pain) and having the undesired effect of increasing cholesterol and triglycerides in humans (Benjamin et al., 2015; Lehnen et al., 2015). To date, no definitive statement can be made on the effect CLA has on weight loss as the limited studies in humans do not reflect the promising and consistent results shown in animal models, nor do they take into consideration other factors such as gender, age, food intake, physical exercise, and genetic polymorphisms (Benjamin et al., 2015; Lehnen et al., 2015).
Ephedra (a.k.a. má huáng) is a plant native to China which has been used in traditional medicine and contains 4 active alkaloid isomers, with ephedrine being the most potent (Diepvens, Westerterp and Westerterp-Plantenga, 2007; Alraei, 2010; National Institutes of Health, 2020). From the 1990s, supplements containing ephedra (often combined with caffeine) was all the rage for weight loss, energy, and enhancing athletic performance until 2004 when it was banned in the US by the Food and Drug Administration (FDA) due to safety concerns (U.S. Food and Drug Administration, 2004). Ephedrine is a sympathomimetic amine that stimulates the sympathetic nervous system to increase blood pressure and heart rate, possibly increase thermogenesis and energy expenditure, and suppress appetite (U.S. Food and Drug Administration, 2004; Diepvens, Westerterp and Westerterp-Plantenga, 2007). Several harmful side effects were reported to be associated with its use, including hypertension, palpitations, stroke, cardiac infarction, and even death (U.S. Food and Drug Administration, 2004; National Institutes of Health, 2020).
In spite of these supplements gaining widespread popularity in recent years, there has been an obvious trend of a lack of research into the efficacy, safety, and cross-reactivity of their constituents. However, pharmaceutical companies and manufacturers continue to disregard this and market their products to unsuspecting customers. More often than not, those who believe the anecdotal results of these supplements end up either just wasting their money if they are lucky, or with lasting damage to their bodies. It can safely be said that the WLS market is here to stay as the growing obese population and social norms continue to drive its growth, therefore, it should come under stricter regulation and scientific scrutiny (Technavio, 2020). In the meantime, it can be said that weight loss is no exception to the saying “no pain, no gain” (or loss in this case).
References:
Alraei, R., 2010. Herbal and Dietary Supplements for Weight Loss. Topics in Clinical Nutrition, 25(2), pp.136-150.
Benjamin, S., Prakasan, P., Sreedharan, S., Wright, A. and Spener, F., 2015. Pros and cons of CLA consumption: an insight from clinical evidences. Nutrition & Metabolism, 12(1), p.4.
Dickinson, A. and MacKay, D., 2014. Health habits and other characteristics of dietary supplement users: a review. Nutrition Journal, 13(1).
Diepvens, K., Westerterp, K. and Westerterp-Plantenga, M., 2007. Obesity and thermogenesis related to the consumption of caffeine, ephedrine, capsaicin, and green tea. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 292(1), pp.R77-R85.
Heber, D., 2003. Herbal preparations for obesity: are they useful?. Primary Care: Clinics in Office Practice, 30(2), pp.441-463.
Lehnen, T., da Silva, M., Camacho, A., Marcadenti, A. and Lehnen, A., 2015. A review on effects of conjugated linoleic fatty acid (CLA) upon body composition and energetic metabolism. Journal of the International Society of Sports Nutrition, 12(1).
Lubowiecki-Vikuk, A., Król-Zielińska, M. and Kantanista, A., 2019. Consumption of dietary supplements to support weight reduction in adults according to sociodemographic background, body mass index, waist-hip ratio, body fat and physical activity. Journal of Health, Population and Nutrition, 38(1).
Mohamed Ansari, R. and Omar, N., 2017. Weight Loss Supplements: Boon or Bane?. Malaysian Journal of Medical Sciences, 24(3), pp.1-4.
Office of Dietary Supplements – Dietary Supplements for Weight Loss. 2020. National Institutes of Health. [online] Available at: <https://ods.od.nih.gov/factsheets/WeightLoss-HealthProfessional/#en11> [Accessed 20 March 2021].
Pittler, M. and Ernst, E., 2004. Dietary supplements for body-weight reduction: a systematic review. The American Journal of Clinical Nutrition, 79(4), pp.529-536.
Semwal, R., Semwal, D., Vermaak, I. and Viljoen, A., 2015. A comprehensive scientific overview of Garcinia cambogia. Fitoterapia, 102, pp.134-148.
Technavio, 2020. Global Weight Loss Supplement Market 2020-2024. Weight Loss Supplement Market by Distribution Channel and Geography – Forecast and Analysis. Infiniti Research Limited.
U.S. Food and Drug Administration, 2004. Final Rule Declaring Dietary Supplements Containing Ephedrine Alkaloids Adulterated Because They Present an Unreasonable Risk. U.S. Food and Drug Administration.
Imperial Bioscience Review 