Nutrition Market

Over-the-Counter Supplements for Weight Loss: What Works?

Over-the-Counter Supplements for Weight Loss: What Works?


Over-the-counter (OTC) supplements for weight loss have gained immense popularity in recent years, with many people turning to these products in hopes of shedding excess kilos. However, the effectiveness and safety of these supplements often come into question, as they lack strong scientific evidence to support their claims (Manore & Patton-Lopez, 2022). While some OTC supplements may offer modest weight loss benefits when combined with a balanced diet and regular exercise, it is crucial to approach them with caution and understand their limitations.

The allure of quick and easy weight loss solutions has led to a booming market for OTC supplements, but the reality is that sustainable weight management requires a comprehensive approach. This article aims to provide an in-depth look at popular OTC supplements for weight loss, examining the available scientific evidence, potential benefits, safety concerns, and the importance of lifestyle changes in achieving and maintaining a healthy weight. By understanding the facts behind these supplements, readers can make informed decisions about their weight loss journey and prioritise evidence-based strategies for long-term success.

Specific Supplements and Their Potential Benefits

Conjugated Linoleic Acid (CLA)

Conjugated Linoleic Acid (CLA) is a naturally occurring fatty acid found in meat and dairy products. It has gained attention as a potential weight loss supplement due to its purported ability to reduce body fat. A meta-analysis by Whigham et al. (2007) found that CLA supplementation resulted in a small but significant reduction in body fat mass, with an average additional loss of 1.5 pounds (0.7 kg) compared to placebo over at least 6 months. However, the effect size was modest, and the authors noted that the clinical relevance of such a small change in body composition remains unclear.

Furthermore, human studies have shown little effect of CLA on appetite and food intake. Watras et al. (2007) found no significant differences in appetite ratings or energy intake between CLA and placebo groups over a 6-month period. Similarly, Kamphuis et al. (2003) reported no effect of CLA on appetite or food intake in overweight subjects during a 13-week study. These findings suggest that CLA’s potential weight loss benefits may not be mediated through appetite suppression.

Garcinia Cambogia

Garcinia cambogia is a tropical fruit native to Southeast Asia, and its extract, hydroxycitric acid (HCA), has been promoted as a weight loss aid. A systematic review and meta-analysis by Onakpoya et al. (2011) examined the efficacy of garcinia extract for weight loss. The analysis included 12 randomised controlled trials, with participants receiving 1000-2800 mg of HCA per day for 2-12 weeks. The results showed a small but significant difference in weight loss favouring HCA over placebo, with a mean difference of 1.94 pounds (0.88 kg). However, the authors noted that the magnitude of the effect was small and that future trials should be more rigorous and better reported.

A study by Roongpisuthipong et al. (2007) investigated the effects of garcinia atroviridis, a related species, on weight loss and appetite in obese women. The study found that garcinia atroviridis was more effective than placebo in reducing weight and appetite over a 2-month period. However, the sample size was small, and further research is needed to confirm these findings.


Glucomannan is a water-soluble dietary fibre derived from the konjac plant. It has been proposed to aid weight loss by promoting satiety and reducing calorie absorption. A systematic review by Zalewski et al. (2015) examined the effect of glucomannan on body weight in overweight and obese individuals. The review included 6 randomised controlled trials, with participants receiving 1-4 grams of glucomannan per day for up to 12 weeks. The results showed a non-significant trend towards weight loss, with an average reduction of 6.6 pounds (3 kg) compared to placebo. However, the authors concluded that the evidence was limited, and larger, longer-term studies are needed to establish the efficacy of glucomannan for weight loss.

Green Coffee Bean Extract

Green coffee bean extract contains chlorogenic acid, a compound that has been suggested to have weight loss properties. A randomised, double-blind, placebo-controlled study by Roshan et al. (2018) investigated the effects of green coffee extract supplementation on anthropometric indices, glycaemic control, and appetite in patients with metabolic syndrome. Participants received 400 mg of green coffee extract or placebo twice daily for 8 weeks. The study found significant reductions in body weight, body mass index, and appetite scores in the green coffee extract group compared to placebo.

An earlier meta-analysis by Onakpoya et al. (2011) reviewed the evidence for green coffee extract in weight loss. The analysis included 3 randomised controlled trials, with participants receiving 180-200 mg of green coffee extract per day for 4-12 weeks. The pooled results showed a significant difference in weight loss favouring green coffee extract over placebo, with a mean difference of 6 pounds (2.47 kg). However, the authors noted that the studies were of poor methodological quality and that more rigorous trials are needed to assess the efficacy and safety of green coffee extract.

Chromium Picolinate

Chromium is an essential trace mineral that has been suggested to play a role in carbohydrate and lipid metabolism. Chromium picolinate, a form of chromium supplementation, has been investigated for its potential weight loss effects. A systematic review and meta-analysis by Onakpoya et al. (2013) examined the efficacy of chromium supplementation for overweight and obesity. The review included 11 randomised controlled trials, with a total of 866 participants receiving 137-1000 mcg of chromium per day for 8-26 weeks. The meta-analysis found a small but significant reduction in body weight and body fat percentage favouring chromium supplementation over placebo. The mean difference in weight loss was 1.1 pounds (0.5 kg), and the mean difference in body fat percentage was 0.6%.

However, the authors noted that the quality of the evidence was low, with a high risk of bias in most studies. They concluded that the current evidence is insufficient to support the use of chromium supplements for weight loss and that larger, well-designed trials are needed to clarify its effectiveness and safety.

Safety Concerns and Potential Side Effects

While OTC supplements for weight loss are often marketed as safe and natural alternatives to prescription medications, they can still pose risks and cause adverse effects. Many weight loss supplements contain stimulants, such as caffeine and synephrine, which can increase heart rate and blood pressure (Stohs et al., 2012). Bitter orange, a common ingredient in weight loss supplements, contains synephrine and has been associated with cardiovascular adverse events, particularly when combined with other stimulants (Stohs et al., 2012).

Chromium picolinate, although generally well-tolerated, can cause gastrointestinal side effects such as nausea, diarrhoea, and abdominal discomfort in some individuals (Tian et al., 2013). Long-term safety data on chromium supplementation is limited, and further research is needed to assess its potential risks.

It is important to note that dietary supplements are not as strictly regulated as prescription medications. The U.S. Food and Drug Administration (FDA) does not review supplements for safety and effectiveness before they are marketed, placing the responsibility on manufacturers to ensure their products are safe and properly labelled (Manore & Patton-Lopez, 2022). This lack of oversight can lead to inconsistencies in product quality and potential adulteration with undeclared ingredients.

The Importance of Lifestyle Changes

While OTC supplements may offer some modest benefits for weight loss, it is crucial to recognise that they are not a substitute for a healthy lifestyle. Sustainable weight management requires a comprehensive approach that includes a balanced diet, regular physical activity, and behavioural changes (Manore & Patton-Lopez, 2022).

The evidence for the long-term efficacy and safety of weight loss supplements is limited, and their effects are generally small compared to the benefits of lifestyle modifications. A calorie-controlled diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats, combined with regular exercise, remains the foundation of successful weight loss and maintenance (Manore & Patton-Lopez, 2022).

Engaging in physical activity not only contributes to weight loss but also provides numerous health benefits, such as improved cardiovascular health, increased muscle mass, and better mental well-being (Manore & Patton-Lopez, 2022). Incorporating both aerobic exercise and resistance training can optimise weight loss outcomes and promote overall health.

Consulting with Healthcare Providers

Before starting any weight loss supplement regimen, it is essential to consult with a healthcare provider. Healthcare professionals can provide individualised guidance based on a person’s medical history, current health status, and weight loss goals. They can also help identify potential interactions between supplements and medications, as well as assess the appropriateness of specific supplements for an individual’s needs.

Healthcare providers can also offer support and guidance in developing a comprehensive weight loss plan that incorporates evidence-based strategies, such as dietary modifications, physical activity, and behavioural interventions. They can monitor progress, address any concerns or side effects, and make necessary adjustments to ensure safe and effective weight management.


Over-the-counter supplements for weight loss have gained significant popularity, but their effectiveness and safety remain questionable. While some supplements, such as conjugated linoleic acid, garcinia cambogia, glucomannan, green coffee bean extract, and chromium picolinate, have shown modest weight loss benefits in certain studies, the overall evidence is limited and inconsistent. Many of these supplements have small effect sizes, and their long-term efficacy and safety are not well-established (Manore & Patton-Lopez, 2022; Onakpoya et al., 2011; Zalewski et al., 2015; Roshan et al., 2018; Onakpoya et al., 2013).

It is crucial to approach weight loss supplements with caution and to prioritise lifestyle changes as the foundation of a healthy weight management strategy. A balanced diet, regular physical activity, and behavioural modifications are essential for achieving and maintaining a healthy weight (Manore & Patton-Lopez, 2022). Supplements should not be relied upon as a sole solution for weight loss, and their use should be carefully considered in consultation with healthcare providers. By focusing on evidence-based strategies and making sustainable lifestyle changes, individuals can work towards their weight loss goals while minimising potential risks associated with over-the-counter supplements.

Key Highlights of Learnings and Actionable Tips

  • Before considering supplements for weight loss, focus on getting regular exercise and changing your diet to eat healthier.
  • A multivitamin may be helpful if you have changed your diet to lose weight, to avoid potential nutrient deficiencies from decreased food intake.
  • There is limited high-quality evidence proving the effectiveness of weight loss supplements. Most only result in small amounts of weight loss compared to placebo.
  • Talk to your healthcare provider before taking any weight loss supplements, as they can have side effects and interact with medications.
  • Popular weight loss supplements include chitosan, chromium, magnesium, probiotics/synbiotics, caffeine, green tea extract, and berberine. More research is needed on their effectiveness and long-term safety.
  • Pair any supplement use with a healthy diet and regular exercise for the best chance at achieving weight loss goals. Supplements are not a magic solution on their own.

What are some of the most common side effects of weight loss supplements?

Common side effects of weight loss supplements can include gastrointestinal issues like nausea, diarrhoea, bloating, flatulence, constipation and heartburn. Some stimulant-containing supplements with ingredients like caffeine may cause sleep problems, anxiety, jitteriness, increased heart rate and blood pressure. In high doses, certain supplements have been linked to more serious effects like liver damage, kidney damage, cardiac arrest and seizures.

Are there any vitamins or minerals that are especially important when trying to lose weight?

When restricting calories for weight loss, it’s important to still get adequate amounts of essential vitamins and minerals. A multivitamin may help fill in gaps if your diet has changed significantly. Vitamin B12 has received attention for its potential role in fat metabolism, with low levels linked to obesity in some studies. Magnesium is another mineral of interest, as deficiency is common and has been associated with inflammation, obesity and metabolic issues.

How can I tell if a weight loss supplement is safe and reputable?

Look for supplements that have been tested in well-designed human clinical trials, ideally from reputable universities or research organisations. Be cautious of products making exaggerated weight loss claims or that sound too good to be true. Check that the supplement brand is transparent about ingredients and dosages, follows good manufacturing practices, and has been third-party tested for purity and potency. When in doubt, ask your doctor or pharmacist for guidance on choosing a safe, quality supplement.

Can weight loss supplements be combined or do they interact with each other?

Combining multiple weight loss supplements or taking them with prescription medications can be risky, as there is potential for negative interactions and compounded side effects. For example, taking multiple stimulant-based supplements could dangerously increase heart rate and blood pressure. Supplements may also interact with drugs like blood thinners, diabetes medications and antidepressants. Always inform your doctor about any supplements you are taking to avoid unsafe combinations.

What lifestyle factors are important to consider alongside taking a weight loss supplement?

To see the best results from a weight loss supplement, it needs to be paired with a healthy lifestyle. This means following a balanced diet, controlling portion sizes, limiting processed foods, and getting regular physical activity. Adequate sleep, stress management and staying hydrated are also key for overall health and weight regulation. Supplements should be viewed as a potential extra tool, not a replacement for making positive diet and lifestyle changes.


Manore, M. M., & Patton-Lopez, M. (2022). Should clinicians ever recommend supplements to patients trying to lose weight? AMA Journal of Ethics, 24(5), E345-E352.

Onakpoya, I., Hung, S. K., Perry, R., Wider, B., & Ernst, E. (2011). The use of garcinia extract (hydroxycitric acid) as a weight loss supplement: A systematic review and meta-analysis of randomised clinical trials. Journal of Obesity, 2011, 509038.

Onakpoya, I., Terry, R., & Ernst, E. (2011). The use of green coffee extract as a weight loss supplement: A systematic review and meta-analysis of randomised clinical trials. Gastroenterology Research and Practice, 2011, 382852.

Onakpoya, I., Posadzki, P., & Ernst, E. (2013). Chromium supplementation in overweight and obesity: A systematic review and meta-analysis of randomized clinical trials. Obesity Reviews, 14(6), 496-507.

Roongpisuthipong, C., Kantawan, R., & Roongpisuthipong, W. (2007). Reduction of adipose tissue and body weight: Effect of water soluble calcium hydroxycitrate in Garcinia atroviridis on the short term treatment of obese women in Thailand. Asia Pacific Journal of Clinical Nutrition, 16(1), 25-29.

Roshan, H., Nikpayam, O., Sedaghat, M., & Sohrab, G. (2018). Effects of green coffee extract supplementation on anthropometric indices, glycaemic control, blood pressure, lipid profile, insulin resistance and appetite in patients with the metabolic syndrome: A randomised clinical trial. The British Journal of Nutrition, 119(3), 250-258.

Stohs, S. J., Preuss, H. G., & Shara, M. (2012). A review of the human clinical studies involving Citrus aurantium (bitter orange) extract and its primary protoalkaloid p-synephrine. International Journal of Medical Sciences, 9(7), 527-538.

Tian, H., Guo, X., Wang, X., He, Z., Sun, R., Ge, S., & Zhang, Z. (2013). Chromium picolinate supplementation for overweight or obese adults. The Cochrane Database of Systematic Reviews, 2013(11), CD010063.

Watras, A. C., Buchholz, A. C., Close, R. N., Zhang, Z., & Schoeller, D. A. (2007). The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain. International Journal of Obesity, 31(3), 481-487.

Whigham, L. D., Watras, A. C., & Schoeller, D. A. (2007). Efficacy of conjugated linoleic acid for reducing fat mass: A meta-analysis in humans. The American Journal of Clinical Nutrition, 85(5), 1203-1211.

Zalewski, B. M., Chmielewska, A., & Szajewska, H. (2015). The effect of glucomannan on body weight in overweight or obese children and adults: A systematic review of randomized controlled trials. Nutrition, 31(3), 437-442.e2.

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