Over one billion people worldwide are living with obesity, and it’s estimated that 43% of adults over the age of 18 are overweight. In light of this, weight-loss drugs may seem like a godsend to many. Some of these medications, when taken alongside recommended lifestyle changes in clinical studies, are associated with 3–12% greater weight loss. This can also lead to improvements in type 2 diabetes, high blood pressure, and abnormal cholesterol levels.
However, these drugs often come with a wide range of side effects, some of which may negatively impact long-term health (details of which can be found at the end of this post). Many clinical trials also report high drop-out rates.
What’s often overlooked in the promotion of these single-compound drugs are the safe and effective long-used plant-based drugs and preventative medicine, that science is increasingly validating.
At Dilston Physic Garden, we encourage exploring safe, plant-based polypharmacological interventions shown effective in controlled scientific studies, that do not carry the risks associated with purified, single-compound pharmaceutical formulations. The polypharmacological effects of plant medicine means they contain multiple active compounds that act on different pathways in the body.
Although lifestyle changes in diet and physical activity remain the foundation of long-term weight loss — creating a balance between calorie intake and energy expenditure, this is a difficult challenge for many. Weight-loss drugs can appear to offer a quick and appealing shortcut.
Plant medicine however presents a viable alternative. Thanks to their complex chemistry, many medicinal plants not only support metabolism, and reduce appetite, they actively improve digestion, and promote overall metabolic health through multiple mechanisms of action.
Dietary supplements are also popular, largely due to their perceived low toxicity and easy availability. Health food shops and online stores offer a vast range of options, including vitamins, minerals, amino acids, metabolites, and of course, a wide variety of herbs and so-called ‘weight-loss pills’. But caution is crucial, especially with online products. Unlike regulated plant medicines, some supplements—particularly herbal slimming pills—can contain hidden synthetic drugs or toxic ingredients. For example, certain products have been found to contain sibutramine, a banned pharmaceutical agent (see more at the end of this post).
We strongly recommend sourcing all herbal supplements and plant medicines from well-established and reputable suppliers.
Above all, regularly including edible medicinal plants in your diet not only supports healthy weight management, but also promotes long-term cardiovascular, metabolic, immune, respiratory and brain health as well as overall wellbeing.
Overall Benefits of Plant-based Pharmaceuticals
Before you read some of the plant-based solutions, bear in mind that this natural approach offers several key advantages over conventional weight loss drugs:
Fewer Side Effects: When taken correctly plant medicine options typically causes few side effects, making them better for, and gentler on the body (Hursel et al., 2009; Neelakantan et al., 2014).
Multiple Benefits: Many of the plants extracts contain a rich bioactive chemistry, that offers a host of additional health benefits, improving digestion, reducing inflammation, controlling blood sugar, lipids, oxidation, inflammation and supporting cardiovascular health and mental health, for example. Many of these aspects of health are also directly affected in those who are overweight.
Sustainable Choices: Plant-based solutions align with sustainable practices, benefiting both the individual and the environment.
Effective, Safe Medicinal Plants for Weight Management
A meta-analysis (a review of 279 relevant clinical trials in obese people) stated that for whole or processed plant products, plant medicine treatments containing green tea, common bean, Malabar tamarind, nigella (kalonji), puerh tea, African mango, and caralluma were found to be beneficial in managing obesity.
Leading the way with scientific evidence in clinical studies, is the humble green tea, though there are many more with clinical evidence – from flaxseed, spinach, and fenugreek showing appetite-suppressing effects to common bean, oats and nigella seed intake significantly improving weight, triglycerides and cholesterol profiles:
DRINKS
Green Tea Extract (Camellia sinensis)
Mechanism and Benefits: Rich in catechins, especially epigallocatechin gallate (EGCG), green tea supports thermogenesis and fat oxidation, helping to boost metabolism naturally. Meta-analysis shows that green tea intake significantly improves body weight, waist circumference, hip circumference, and cholesterol levels.
– Supporting Study: Hursel, R., et al. (2009). “Green Tea Catechin and Caffeine Synergy on Thermogenesis.” American Journal of Clinical Nutrition, 89(6), 1798-1804.
Puerh Tea (Camellia sinensis var. assamica)
Mechanism and Benefits: Puerh tea supports weight management by enhancing lipid metabolism and reducing cholesterol. Studies indicate benefits for reducing BMI and weight in individuals with obesity. Having black tea (without milk) is better for absorbing the beneficial ingredients: for example black tea increased vascular function (FMD) compared to black tea with milk. Compared with hot water, black tea did not alter blood pressure, while black tea with milk increased systolic and diastolic blood pressure. Black tea and black tea with milk lowered heart rate compared to hot water.
– Supporting Studies: Zhang, M., et al. (2012). “A Meta-Analysis of Weight Loss with Green, Oolong, and Puerh Teas.” Journal of Clinical Biochemistry and Nutrition, 50(4), 220-226; Ahmad et al. (2018). “Effect of adding milk to black tea on vascular function in healthy men and women: a randomised controlled crossover trial” Food Funct. 13;9(12):6307-6314.
VEGETABLES
Common Bean (Phaseolus vulgaris)
Mechanism and Benefits: Compounds in common beans reduce the digestion and absorption of starch, leading to reduced calorie intake and improved blood sugar regulation. Research indicates it aids in weight loss and improves triglyceride levels.
– Supporting Study: Barrett, M. L., et al. (2011). “Effects of Phaseolus vulgaris on Body Weight and Composition in Overweight Adults.” Journal of Obesity, 2011, 320416.
Spinach (Spinacia oleracea)
Mechanism and Benefits: Spinach contains thylakoids, compounds that promote satiety and reduce appetite by slowing fat digestion.
– Supporting Study: Montelius, C., et al. (2014). “Thylakoids from Spinach Suppress Appetite and Increase Weight Loss in Humans.” Appetite, 82, 17-23.
Caralluma (Caralluma fimbriata) – edible cactus
Mechanism and Benefits: This edible cactus-like plant is known for its appetite-suppressing properties. Research is variable, however some studies show it can reduce food intake and promote feelings of fullness.
– Supporting Study: Kuriyan, R., et al. (2007). “Effect of Caralluma Fimbriata Extract on Appetite, Food Intake and Anthropometry in Adults.” Appetite, 48(3), 338-344.
SEEDS
Oats (Avena sativa)
Mechanism and Benefits: Consumption of a whole-grain RTE (ready-to-eat) oat cereal as part of a dietary program for weight loss had favourable effects on fasting lipid levels and waist circumference. LDL cholesterol level, and total cholesterol and non-high-density lipoprotein-cholesterol were reduced significantly more with whole-grain RTE oat cereal versus control.
– Supporting Study: Maki et al. (2010) “Whole-grain ready-to-eat oat cereal, as part of a dietary program for weight loss, reduces low-density lipoprotein cholesterol in adults with overweight and obesity more than a dietary program including low-fibre control foods.” J Am Diet Assoc.: 110(2):205-14.
Flaxseed or Linseed (Linum usitatissimum)
Mechanism and Benefits: Flaxseed is high in fibre, which increases satiety and supports digestive health. It regulates blood sugar, making it easier to maintain balanced eating habits. Flaxseed is often promoted for digestive health – indigestion/heartburn, constipation and diarrhoea by our associated pharmacist Milena Kopkowska, trained in dispensing plant medicine alongside mainstream medicine.
– Supporting Study: Soltanian, N., et al. (2018). “Effects of Flaxseed on Weight and Inflammatory Markers: A Systematic Review.” Nutrition Reviews, 76(11), 907-918.
SPICES
Ginger (Zingiber officinale)
– Mechanism and Benefits: Ginger boosts calorie burning and regulates appetite, supporting gradual weight loss.
– Supporting Study: Mansour, M. S., et al. (2018). “Ginger: An Anti-Obesity Agent.” Critical Reviews in Food Science and Nutrition, 59(15), 1-12.
Fenugreek (Trigonella foenum-graecum)
Mechanism and Benefits: Rich in fibre, fenugreek increases feelings of fullness and help regulate blood sugar levels, making it easier to maintain balanced eating habits.
– Supporting Study: Neelakantan, N., et al. (2014). “Effect of Fenugreek on Glycemia and Insulin Resistance.” Journal of Nutrition, 144(2), 171-180.
Nigella or Kalonji (Nigella sativa)
Mechanism and Benefits: Renown for its general health-boosting effects, and its anti-inflammatory properties, nigella improves weight and triglycerides by regulating metabolism and lipid levels.
– Supporting Study: Sabzghabaee, A. M., et al. (2012). “Clinical Evaluation of Nigella sativa for the Treatment of Obesity.” Phytotherapy Research, 26(4), 526-529.
Cayenne Pepper (Capsicum annuum)
Mechanism and Benefits: Capsaicin, the active ingredient in cayenne pepper, promotes thermogenesis, helping to burn more calories and suppressing appetite.
– Supporting Study: Whiting, S., et al. (2012). “Capsaicinoids and Weight Management: A Systematic Review and Meta-Analysis.” Appetite, 59(2), 341-348.
FRUIT
Bitter orange or Seville orange (Citrus aurantium).
Mechanisms and Benefits: Several studies show positive effects of bitter orange extract or its active chemical synephrine on weight loss. A single dose of synephrine alone increased basal metabolic rate in humans. Synephrine derived from C. aurantium is safe when taken up to 98 mg/day for 60 days. Caution: synephrine increases blood pressure and heart rate.
– Supporting Study – Kaats et al. (2013) “A 60day double-blind, placebo-controlled safety study involving Citrus aurantium (bitter orange) extract.” Food Chem Toxicol.: 55:358-62.
Mechanism and Benefits: African mango is high in fibre and promotes satiety, supporting weight loss by helping to reduce calorie intake. It’s also been shown to improve cholesterol and triglyceride levels.
– Supporting Study: Ngondi, J. L., et al. (2009). “The Use of Irvingia gabonensis Seed Extract in the Management of Overweight.” Lipids in Health and Disease, 8(1), 7.
Malabar Tamarind, Garcinia gummi-gutta (Garcinia Cambogia)
Mechanism and Benefits: Its constituent hydroxycitric acid (HCA) is linked to reduced fat storage and appetite control. While effects vary, studies show modest benefits in weight management when combined with a healthy diet.
– Supporting Study: Onakpoya, I., et al. (2011). “The Use of Garcinia Cambogia Extract as a Natural Weight Loss Supplement: A Meta-Analysis.” Journal of Obesity, 2011, 509038.
SUMMARY
More high-quality studies are needed to further explore the mechanisms of the different plant medicine treaments in addressing obesity. There is clear evidence that:
Taking these plant medicines – that is taking the plants at a medicinal level, actively supports weight loss.
Regularly adding these medicinal plants to your daily diet snot only supports healthy weight maintenance, but supports the physiological abnormalities associated with the development of cardiovascular disease and type 2 diabetes, as well as support overall long-term health.
CAUTION Do not stop taking medication you have been prescribed without consulting your healthcare provider. When taking any plant medicine for the first time, first consult a NIMH registered medical herbalist, just as you would consult your pharmacist or GP, to ensure the right plant medicine fit for individual needs and if you are pregnant, have any diagnosed conditions, or are taking any medications.
Side Effects of Prescription Weight-Loss Drugs
Despite advances in weight-loss treatments, including prescribed drugs that may be effective when used carefully and in combination with lifestyle adjustments, there are well-known risks associated with some of the commonly used drugs, and some have been withdrawn from the market due to links with cancer:
Common Side Effects of Prescription Weight-Loss Drugs
Serious Side-Effects Associated with Certain Weight-Loss Drugs
Weight loss drugs like appetite suppressants, fat blockers, and stimulants work by altering bodily processes, often causing significant side effects. These side effects, while sometimes variable by individual, are supported by studies documenting how these drugs impact body systems over short and long terms:
Increased Heart Rate and Blood Pressure Weight-loss medications, especially those with stimulant properties, can elevate heart rate and blood pressure. – Supporting Study: Verma, S., et al. (2018). “Cardiovascular and Weight Loss Drugs: A Systematic Review.” International Journal of Cardiology, 255, 219-226.
Mood Changes, Anxiety, and Depression Stimulant-based drugs, such as those containing phentermine, have been associated with mood swings, increased anxiety, and even depression, particularly with prolonged use. – Supporting Study: Carpenter, C. J., et al. (2018). “Side Effects of Stimulant-Based Weight Loss Medications.” Psychology Today.
Digestive Discomfort (Bloating, Gas, Diarrhoea) Fat blockers like orlistat interfere with fat absorption, which can lead to gastrointestinal issues including bloating, gas, and diarrhoea. – Supporting Study: Padwal, R., & Majumdar, S. R. (2007). “Drug Treatments for Obesity: Orlistat, Sibutramine, and Rimonabant.” The Lancet, 369(9555), 71-77.
Insomnia and Restlessness Stimulant-containing weight-loss medications, such as phentermine, are known to disrupt sleep, leading to insomnia and restlessness. – Supporting Study: Hendricks, E. J., & Greenway, F. L. (2011). “A Study of Stimulant Medication and Insomnia in Patients Treated for Obesity.” The American Journal of Drug and Alcohol Abuse, 37(5), 486-493.
Kidney and Liver Health Risks Certain weight-loss drugs, like orlistat, may impact liver and kidney function, particularly with long-term use. – Supporting Study: Lockwood, C. M., et al. (2017). “Orlistat-Associated Adverse Liver Injury: A Report of Two Cases and a Review of the Literature.” Journal of Clinical Gastroenterology, 51(9), 805-808.
Dependency and Withdrawal Symptoms Drugs such as phentermine can lead to dependency, with users experiencing withdrawal symptoms upon cessation. – Supporting Study: Grilo, C. M., et al. (2019). “Long-term Effects of Weight Loss Medications.” Journal of Clinical Psychiatry, 80(6).
Nausea and Vomiting Drugs like liraglutide, used for weight loss, commonly cause nausea and, less frequently, vomiting. – Supporting Study: Pi-Sunyer, X., et al. (2015). “A Randomized Controlled Trial of 3.0 mg of Liraglutide in Weight Management.” New England Journal of Medicine, 373, 11-22.
Headaches and Dizziness Some users of phentermine and other stimulants experience headaches and dizziness, which can hinder daily functioning. – Supporting Study: Bray, G. A., et al. (2016). “Safety and Tolerability of Phentermine in Obesity: A Meta-Analysis.” Obesity Reviews, 17(7), 793-802.
Gallstones Rapid weight loss associated with weight-loss drugs can increase the risk of gallstone formation. – Supporting Study: Shiffman, M. L., et al. (1993). “Gallstone Formation after Rapid Weight Loss: A Prospective Study.” Gastroenterology, 104(3), 912-916.
Fatigue and Weakness Calorie restriction combined with some weight-loss drugs may lead to physical fatigue and weakness, impacting quality of life and in turn overall health. Some semaglutide drugs (such as Ozempic) have been shown to impact positive behaviours, such as lowering the desire to exercise in laboratory studies. – Supporting Study: Jensen, M. D., et al. (2014). “Obesity and Fatigue: Assessment and Management.” Journal of Clinical Endocrinology & Metabolism, 99(3), 748-756.
There is also evidence suggesting that some weight-loss drugs may be associated with an increased risk of certain cancers and neuropsychiatric conditions:
1. Orlistat and Cancer
Orlistat, a common fat-blocking weight-loss drug, has raised concerns about its ability to cause liver injury and its potential association with an increased risk of colorectal cancer. Although cancer risk studies short follow-up times limit conclusions, this association has not yet been proven, and in fact Orlistat appears to have beneficial anti-cancer properties. Orlistat blocks the absorption of fat in the intestine, which may lead to changes in the gut environment overtime and is associated with liver injury.
– Supporting Study: Nickell, S. P., et al. (2014). “Risk of Colorectal Cancer in Users of Orlistat: Population Based Cohort Study.” BMJ, 349, g4483.
– Supporting Study: Haslam, D. W., et al. (2017). “Safety Concerns in Anti-Obesity Drugs: Orlistat, Lorcaserin, and Sibutramine.” Current Obesity Reports, 6(2), 165-171.
Sibutramine and Cardiovascular Risk
Sibutramine (Reductil), an appetite suppressant is no longer available in the U.S. and European markets due to safety concerns. It has been associated with serious cardiovascular adverse events. Unfortunately, Sibutramine can be a hidden active agent in supposed herbal weight-loss pills sold online and use of these has caused hospital admissions.
– Supporting Study: Wang, Y., et al. (2013). “Safety Concerns with Sibutramine: A Review of its Hepatotoxicity and Other Adverse Effects.” Drug Safety, 36(5), 333-344.
Lorcaserin and Cancer Risk
Lorcaserin, an appetite suppressant approved by the FDA in 2012, was withdrawn from the market in 2020 due to an increased incidence of cancer observed in a post-marketing clinical trial. The trial reported a higher number of cases of various cancers, including pancreatic, colorectal, and lung cancers, in patients who took Lorcaserin compared to those who took a placebo, and a subsequent meta-analysis review also confirm a trend this direction.
– Supporting Study: U.S. Food and Drug Administration (FDA). (2020). “FDA Requests the Withdrawal of the Weight-Loss Drug Belviq, Belviq XR (Lorcaserin) from the Market.” FDA website.
Rimonabant and Neuropsychiatric Concerns
Like Orlistat, Rimonabant may have anti-cancer properties, however Rimonabant (a CB1 antagonist appetite suppressant) was withdrawn from the market due to serious psychiatric side effects (an increased risk of anxiety, depression and suicide).
– Supporting Study: Topol et al. (2010) “Rimonabant for prevention of cardiovascular events (CRESCENDO): a randomised, multicentre, placebo-controlled trial.” Lancet. 2010 Aug 14;376(9740):517-23.
Summary of Serious Side Effect Risks
Each of these drugs has either been withdrawn from the market or, such as with Orlistat in the UK, is prescribed with caution in countries where it’s still available.
While these findings are significant, they also highlight the need for more long-term studies on weight-loss drugs, as cancer can take years to develop and neuropsychiatric risks may differ with individuals and both may be influenced by multiple factors.
What to take away?
Obesity is a major global health concern linked to numerous complications including heart disease, stroke, type-2 diabetes, 13 types of cancer, fatty liver disease, osteoarthritis, digestive issues, sleep apnoea, and mental health challenges.
The only way to address this long-term is through health awareness and lifestyle changes. Education in health awareness, nutrition, and safe use of medicinal plants, that can also be preventative medicine, is not taught in schools. It must now be seen as important as maths and english and taught alongside these subjects every day in school.
A holistic approach that includes plant-based support and balanced nutrition and exercise, will provide sustainable, long-term results. The existing evidence of using drugs with a range of side effects underlines the importance of exploring safe, phytochemical-rich pharmaceuticals as alternatives for weight management, particularly when considering potential long-term risks like cancer.
What’s more, as we’ve explored the plant-based treatment options, it’s also important that not only are they a safer solution to drugs when used correctly, but they also have a rich range of effects that promote cardiovascular, metabolic and digestive health, mental wellbeing, as well as lower risk of certain cancers.
Through our Resources pages, Dilston Physic Garden invites you to explore plant-based medicine. By understanding and utilising our forgotten heritage, which is now science-based, we can help maintain a healthy weight, and an overall healthier body and mind long-term.
