Introduction
Losing weight is a common goal for many Australians, with over two-thirds of adults classified as overweight or obese (Australian Institute of Health and Welfare, 2020). While adopting a balanced diet and regular physical activity are the cornerstones of healthy weight management, some people turn to dietary supplements for extra support. In fact, a recent survey found that 24% of Australians have used at least one weight loss product in the past 12 months (Roy Morgan, 2019). However, the effectiveness and safety of many good supplements for weight loss remain questionable.
The global weight loss supplement market is expected to reach $33.4 billion by 2027 (Grand View Research, 2020), fuelled by the increasing prevalence of obesity and the desire for quick solutions. However, the Therapeutic Goods Administration (TGA) in Australia has expressed concerns about the quality and safety of some weight loss products, with many containing undeclared or banned substances that can cause serious adverse effects (TGA, 2020). Furthermore, most supplements have limited high-quality evidence from randomised controlled trials to support their efficacy for weight loss.
This article aims to provide a comprehensive overview of the most common ingredients found in good supplements for weight loss, examining the current scientific evidence for their effectiveness and safety. We will also discuss the potential risks and considerations when using weight loss supplements, and provide recommendations for individuals seeking to manage their weight safely and sustainably. By the end of this guide, readers will have a better understanding of the role that supplements can play in a holistic weight loss approach, and be equipped to make informed decisions about their use.
Common Ingredients in Weight Loss Supplements
Caffeine
Caffeine is a popular stimulant found in many weight loss supplements due to its potential to boost metabolism and increase fat oxidation. A meta-analysis by Tabrizi et al. (2019) found that caffeine intake was associated with significant reductions in weight, BMI, and body fat compared to placebo. The authors suggested that caffeine’s thermogenic effects may be responsible for these weight loss benefits.
However, the long-term efficacy and safety of caffeine for weight management remain uncertain. Excessive caffeine consumption can lead to adverse effects such as insomnia, anxiety, digestive issues, and increased heart rate (Temple et al., 2017). Furthermore, the weight loss effects of caffeine may be more pronounced in lean individuals compared to those with obesity (Arciero et al., 2018).
When combined with other stimulants like green tea extract or bitter orange, caffeine may enhance weight loss but also increase the risk of side effects. A review by Jurgens et al. (2012) concluded that the combination of caffeine and ephedra (now banned) was associated with twice the weight loss compared to placebo, but also a higher incidence of adverse events.
Green Tea Extract
Green tea extract, derived from the leaves of Camellia sinensis, is another common ingredient in weight loss supplements. It contains caffeine and polyphenols called catechins, particularly epigallocatechin gallate (EGCG), which have been proposed to increase energy expenditure and fat oxidation (Jurgens et al., 2012).
A meta-analysis by Hursel et al. (2011) found that catechin-caffeine mixtures from green tea induced a small but significant increase in energy expenditure and fat oxidation compared to placebo. However, the weight loss effects were modest, with a mean difference of -1.31 kg over 12 weeks.
The safety profile of green tea extract appears to be better than some other stimulant-based supplements. A Cochrane review by Jurgens et al. (2012) concluded that green tea preparations were well-tolerated, with mild to moderate adverse effects such as constipation and abdominal discomfort. However, there have been rare case reports of liver toxicity associated with high-dose green tea extract consumption (Mazzanti et al., 2009).
Garcinia Cambogia
Garcinia cambogia is a tropical fruit that contains hydroxycitric acid (HCA), which has been claimed to inhibit fat synthesis and suppress appetite. It is a popular ingredient in many weight loss supplements, but the evidence for its efficacy is mixed.
A meta-analysis by Onakpoya et al. (2011) found that garcinia cambogia extract produced small, statistically significant short-term weight loss compared to placebo (-0.88 kg). However, the clinical relevance of this modest effect size is uncertain. The authors also noted that most of the included trials were of poor methodological quality.
There are also concerns about the safety of garcinia cambogia, particularly at high doses. Animal studies have suggested that HCA may cause testicular toxicity and spermatogenic dysfunction (Kolla et al., 2018). In humans, garcinia cambogia has been associated with liver damage in several case reports, although causality is difficult to establish (Crescioli et al., 2018).
Glucomannan
Glucomannan is a soluble dietary fiber derived from the root of the konjac plant. It is often promoted as an appetite suppressant and weight loss aid due to its ability to absorb water and form a viscous gel in the gastrointestinal tract, potentially increasing satiety and delaying gastric emptying (Keithley et al., 2013).
However, the evidence for glucomannan’s weight loss effects is inconsistent. A meta-analysis by Zalewski et al. (2015) found that glucomannan supplementation led to a small, statistically significant reduction in body weight compared to placebo (-0.39 kg). The authors concluded that while glucomannan may be a useful adjunct to lifestyle modifications for weight loss, more research is needed to establish its long-term efficacy and safety.
Glucomannan is generally well-tolerated, but gastrointestinal side effects like bloating, flatulence, and diarrhea can occur (Keithley et al., 2013). There have also been rare reports of esophageal and gastrointestinal obstruction associated with glucomannan tablets, particularly when taken without adequate fluid intake (Vanderbeek et al., 2007).
Chromium
Chromium is an essential trace mineral that has been proposed to enhance insulin sensitivity, reduce body fat, and increase lean muscle mass. It is often included in weight loss supplements, particularly in the form of chromium picolinate.
However, the weight loss effects of chromium supplementation appear to be minimal. A meta-analysis by Onakpoya et al. (2013) found that chromium supplementation resulted in a small, statistically significant reduction in body weight compared to placebo (-0.50 kg). The authors noted that the clinical significance of this modest effect is uncertain.
The safety of chromium supplementation has also been questioned. High doses of chromium picolinate (>1000 mcg/day) have been associated with kidney damage, muscular effects, and alterations in neurotransmitter levels in case reports (Cerulli et al., 1998). Chromium may also interact with medications, particularly antidiabetic drugs, leading to hypoglycemia (Ioannides-Demos et al., 2002).
Efficacy of Weight Loss Supplements
Despite their popularity, the overall efficacy of weight loss supplements remains questionable. Most of the individual ingredients discussed above have only shown modest, short-term weight loss effects in meta-analyses and systematic reviews, with mean differences ranging from -0.39 to -1.31 kg compared to placebo (Jurgens et al., 2012; Onakpoya et al., 2011; Zalewski et al., 2015).
The methodological quality of many trials investigating weight loss supplements is also poor, with small sample sizes, short durations, and high attrition rates (Dwyer et al., 2005). This limits the reliability and generalisability of their findings. Furthermore, publication bias may overestimate the efficacy of some supplements, as studies with negative results are less likely to be published (Onakpoya et al., 2011).
The long-term efficacy and sustainability of weight loss achieved through supplementation are also uncertain. Most trials have only investigated short-term effects over 8-12 weeks, and there is a lack of evidence on whether weight loss is maintained after supplementation is ceased (Jurgens et al., 2012). Some studies have even suggested that weight loss supplements may lead to greater weight regain compared to placebo, possibly due to rebound effects on appetite and metabolism (Pittler & Ernst, 2004).
It is also important to note that weight loss supplements are not a magic bullet for obesity management. They should not be relied upon as the sole strategy for weight loss, but rather be used as an adjunct to a balanced diet, regular physical activity, and other lifestyle modifications (Dwyer et al., 2005). The most effective and sustainable approach to weight management is one that focuses on gradual, long-term changes to dietary and physical activity habits (NHMRC, 2013).
Safety Concerns and Adverse Effects
The safety of weight loss supplements is a major concern, as they are not as strictly regulated as pharmaceutical drugs. In Australia, most weight loss products are considered complementary medicines and are regulated by the TGA through the Listed Medicines Scheme (TGA, 2020). This means that they are not subject to the same rigorous pre-market evaluation as registered medicines, and the onus is on the manufacturer to ensure their safety and quality.
As a result, weight loss supplements may contain undeclared, untested, or banned ingredients that can cause serious adverse effects. For example, the TGA has identified several weight loss products adulterated with sibutramine, a prescription weight loss drug that was withdrawn from the market due to its association with cardiovascular events and strokes (TGA, 2010). Other contaminants found in weight loss supplements include amphetamines, benzodiazepines, and toxic herbs like ephedra (Coogan, 2010).
Even supplements containing legal ingredients can cause adverse effects, particularly when taken in high doses or combined with other substances. Common side effects of weight loss supplements include gastrointestinal symptoms (e.g. nausea, diarrhea, abdominal pain), headaches, insomnia, anxiety, palpitations, and raised blood pressure (Dwyer et al., 2005). More serious adverse events like liver toxicity, kidney failure, and cardiovascular events have also been reported in association with certain ingredients, such as green tea extract, garcinia cambogia, and synephrine (Crescioli et al., 2018; Mazzanti et al., 2009; Stohs et al., 2012).
Certain population groups may be at higher risk of adverse effects from weight loss supplements. Pregnant and breastfeeding women should avoid these products due to the lack of safety data and potential harm to the fetus or infant (Ramachenderan et al., 2008). Children and adolescents are also more susceptible to the negative effects of stimulant-based supplements on growth, development, and cardiovascular function (Seifert et al., 2011). People with pre-existing health conditions like hypertension, arrhythmias, and liver or kidney dysfunction should also exercise caution with weight loss supplements due to the risk of exacerbating their condition or interacting with their medications (Saper et al., 2004).
Recommendations for Consumers
Given the limited evidence for efficacy and the potential safety concerns, consumers should be cautious when considering the use of weight loss supplements. The following recommendations can help individuals make informed decisions and minimise their risk of adverse effects:
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Consult a healthcare professional: Before starting any weight loss supplement, it is important to consult with a doctor or Accredited Practising Dietitian to discuss its potential benefits and risks, and to ensure it is appropriate for your individual health status and goals.
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Be wary of exaggerated claims: If a supplement sounds too good to be true, it probably is. Be skeptical of products that promise rapid or effortless weight loss, or that claim to be a “miracle cure” for obesity.
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Check for TGA approval: In Australia, all complementary medicines must be entered on the Australian Register of Therapeutic Goods (ARTG) before they can be legally supplied. Consumers can search the ARTG database to check if a product has been assessed by the TGA for safety and quality.
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Look for third-party certification: Independent organisations like the Therapeutic Goods Administration (TGA) and ConsumerLab.com conduct quality testing of supplements and provide seals of approval to products that meet their standards for purity, potency, and labelling accuracy.
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Read the label carefully: Always check the ingredient list and serving size of a supplement, and be aware of any potential allergens or interactions with medications. Follow the recommended dosage instructions, and do not exceed the stated dose without consulting a healthcare professional.
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Report adverse reactions: If you experience any negative side effects while taking a weight loss supplement, stop using it immediately and report your reaction to the TGA through their online adverse event reporting system.
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Focus on lifestyle changes: Remember that supplements are not a substitute for a healthy diet and regular physical activity. Sustainable weight loss is best achieved through a combination of reduced energy intake, increased energy expenditure, and behaviour modification (NHMRC, 2013).
In conclusion, while some weight loss supplements may offer modest short-term benefits, their overall efficacy and safety remain questionable. Consumers should approach these products with caution, and prioritise lifestyle changes as the foundation of their weight management strategy. If supplements are used, they should be selected carefully, used under medical supervision, and integrated into a comprehensive, evidence-based approach to obesity prevention and treatment.
Conclusion
The use of dietary supplements for weight loss is a complex and controversial topic, with limited evidence to support their efficacy and safety. While some ingredients like caffeine, green tea extract, and glucomannan may offer modest short-term benefits, their effects are often small and not clinically significant compared to placebo. Furthermore, the methodological quality of many studies investigating these supplements is poor, with small sample sizes, short durations, and high attrition rates limiting the reliability and generalisability of their findings.
Safety is a major concern with weight loss supplements, as they are not as strictly regulated as pharmaceutical drugs in Australia. Many products contain undeclared, untested, or banned ingredients that can cause serious adverse effects, particularly when taken in high doses or combined with other substances. Common side effects include gastrointestinal symptoms, headaches, insomnia, anxiety, and raised blood pressure, while more serious events like liver toxicity and cardiovascular complications have also been reported.
Given these uncertainties, consumers should approach weight loss supplements with caution and scepticism. Before starting any supplement, it is crucial to consult with a healthcare professional to discuss its potential benefits and risks, and to ensure it is appropriate for individual health status and goals. Consumers should also be wary of exaggerated claims, check for TGA approval, look for third-party certification, read labels carefully, and report any adverse reactions.
Ultimately, the most effective and sustainable approach to weight management is one that focuses on lifestyle changes, including a balanced diet, regular physical activity, and behaviour modification. While some supplements may be used as an adjunct to these strategies, they should not be relied upon as the sole solution for achieving a healthy weight. By prioritising evidence-based, holistic approaches to obesity prevention and treatment, individuals can improve their health outcomes while minimising their risk of adverse effects from weight loss supplements.
Key Highlights and Actionable Tips
- Many weight-loss supplements contain multiple ingredients that have not been adequately tested in combination with one another. Talk to your health care provider before using any weight-loss supplements to understand potential benefits and risks.
- The best way to lose weight and keep it off is to follow a sensible approach that incorporates a healthy eating plan, reduced caloric intake, and moderate physical activity under the guidance of a health care provider.
- Be cautious of fraudulent claims about weight-loss supplements, such as “lose weight without diet or exercise”. If it sounds too good to be true, it usually is.
- Weight-loss supplements marketed as dietary supplements are sometimes adulterated with prescription drug ingredients, controlled substances, or unstudied pharmaceutically active ingredients that could be harmful.
- Some ingredients in weight-loss supplements can interact with certain medications. Discuss supplement use with your health care provider if you take medications regularly.
What are some common ingredients found in weight-loss supplements?
Common ingredients in weight-loss supplements include botanicals and herbs like green tea, garcinia cambogia, and bitter orange. Other ingredients may include dietary fibre, caffeine, minerals like chromium, and compounds such as conjugated linoleic acid (CLA) and raspberry ketone. Many supplements contain a combination of multiple ingredients.
Are there any weight-loss supplements that have been proven effective?
The evidence supporting the use of dietary supplements to reduce body weight is inconclusive and unconvincing for most supplements that have been studied. While some ingredients may lead to small amounts of weight loss, the effects are usually minimal and not likely to be clinically meaningful. Supplements are not a substitute for a healthy lifestyle.
What are the potential risks of taking weight-loss supplements?
Weight-loss supplements can have side effects and might interact with prescription and over-the-counter medications. In some cases, the active ingredients are unknown or unstudied pharmaceutically active substances that could be harmful. Supplements might also contain ingredients that are not declared on the label, including prescription drugs and controlled substances.
How can I lose weight safely and effectively?
The best approach to losing weight and keeping it off is to follow a healthy eating plan with reduced caloric intake, engage in regular physical activity, and make other positive lifestyle changes. This should be done under the guidance of a health care provider, especially if you have a medical condition or are taking medications.
What should I do if I’m considering taking a weight-loss supplement?
Before taking any weight-loss supplements, talk to your health care provider. They can help you understand the potential benefits and risks, and assess whether the supplement is appropriate for you based on your medical history and current medications. Be sure to look out for fraudulent claims and check whether the supplement has been tested for safety and efficacy in humans.
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