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Obesity afflicts one-third of the U.S. population, with nearly 45% of overweight and 67% of obese individuals trying to lose weight.^1,2 With the beginning of the new year, even more people are likely making resolutions to lose weight.


Weight is a key modifiable risk factor for preventable causes of death due to heart disease, stroke, and type 2 diabetes.¹ Even a modest weight loss of 5% to 10% over 6 months may be beneficial.³ Many dietary supplements claim to promote easy weight loss. One supplement, Garcinia cambogia, claims to have beneficial weight reduction and lipid-lowering effects. 


G. cambogia and HCA


The active ingredient in G. cambogia, hydroxycitric acid (HCA), is a competitive inhibitor of adenosine triphosphate citrate lyase, a key enzyme in the synthesis of fatty acids, cholesterol, and triglycerides. HCA is thought to improve the body’s ability to break down fat, increase satiety, and increase high-density lipoprotein cholesterol. These effects may improve exercise tolerance, decrease fat storage, and improve lipids.⁴


Many G. cambogia products exist, with each containing different HCA concentrations. For weight loss, an extract containing 50% HCA, 1,000 mg three times daily or 500 mg four times daily, has been used. A mild adverse effect profile has been established, including headache, nausea, upper respiratory tract symptoms, and gastrointestinal symptoms.⁴ In 2009, FDA warned patients about the risk of liver toxicity with the dietary supplement Hydroxycut, which contained G. cambogia at the time. However, FDA was unable to determine if G. cambogia was the true cause of the events or if they were attributable to other ingredients.⁵


Key clinical trial


A recent randomized, double-blind study of 43 obese women aged 25 to 60 years evaluated the efficacy of G. cambogia compared with placebo.⁶ Key exclusion criteria were pregnancy/lactation, type 2 diabetes, bariatric surgery, untreated hypertension, smoking cessation within the past 6 months, and use of medications affecting weight. 


Participants received 800 mg (50% HCA) of G. cambogia capsules three times daily or matched placebo 30 minutes before meals. Anthropometric variables such as body mass index (BMI) and free fat mass were measured, among many others. Lipid and lipoprotein values were also evaluated before and after 60 days. All patients followed a dietary plan and were instructed to maintain physical activity throughout the study. 


Results showed no statistical differences between groups except with respect to triglycerides (TG). A significant decrease in TG was observed in the G. cambogia group (−22.9 ± 5.3) compared with an increase in the placebo group (+4.53 ± 33.4). However, patients treated with G. cambogia experienced a slight increase in BMI, while patients receiving placebo had a slight decrease in BMI (+0.17 kg/m² and −0.24 kg/m², respectively). Liver enzymes and creatinine clearance were unchanged. Gastric discomfort occurred in three patients receiving G. cambogia, compared with one patient in the placebo group. This was a small study with a short duration similar to other studies of supplements, and its results do not provide additional clarity for G. cambogia’s use in weight loss and lipids.


What to tell patients


Obesity is associated with an increased risk of cardiovascular disease (CVD) mortality. Although G. cambogia has received media attention for control of weight and cholesterol, the evidence of its benefits remains limited. Patients with CVD risk factors should be encouraged to manage their hypertension, diabetes, and dyslipidemia. A dietary intake of 1,200 to 1,500 kcal/d for women and 1,500 to 1,800 kcal/d for men, along with physical activity, should be encouraged to achieve 5% to 10% of weight loss within 6 months.


References


1. www.cdc.gov/obesity/data/adult.html

2. https://ods.od.nih.gov/factsheets/WeightLoss-HealthProfessional/#en3

3. Obesity. 2014;22(S2):S1–S410

4. www.naturaldatabase.com 

5. www.fda.gov/downloads/ForConsumers/ConsumerUpdates/UCM152222.pdf

6. Phytother. 2014;28:887–91


If you ask me, there’s really only one way to lose weight and keep it off, and that’s to adopt a healthy lifestyle. That includes eating nutritious meals and exercising daily.

But there are plenty of marketers out there would vehemently disagree – because magic pills make money. Acai berry, green tea extract and capsaicin all had their time in the spotlight.

But, let’s explore a supplement that has exploded on the weight loss scene more recently: Garcinia cambogia.

Garcinia cambogia is a small, pumpkin-shaped fruit. You may know it as tamarind. The extract of the fruit is called hydroxycitric acid, and that is what the “magic pills” are made from. But do they work? [9 Meal Schedules: When to Eat to Lose Weight]

Let’s explore the research:

1998 study published in the Journal of the American Medical Association: After a 12-week randomized, double-blind study of overweight men and women, researchers concluded that Garcinia cambogia did not produce significant weight or fat loss above the placebo.

2013 review in the journal Complementary Theories in Medicine: Researchers evaluated clinical trials that used plant extracts as potential treatment for obesity, and found that the evidence was not convincing in most cases. One exception was a combination of Garcinia cambogia taken with another herb called Gymnema sylvestre, which showed a slight increase in weight loss results. It’s a glimmer of hope, but surely, more research needs to be done on the subject.

2005 study in the journal Food and Chemical Toxicology: Researchers tested a high dose of Garcinia cambogia extract on obese male rats. The good news? The rats lost weight! The bad news? Extremely high doses seemed to cause testicular atrophy and toxicity. Yikes!

If you do decide to hop on the latest bandwagon, whether it is Garcinia cambogia or some other plant-based extract, proceed with caution. If you’re talking any prescription medications, talk to your doctor before adding any herbal supplement. There may be dangerous interactions. And as researchers saw in the 2005 study on rats, there may be consequences to taking large doses. [Related: Garcinia Cambogia Supplement Often Lacks Active Ingredient, Study Finds]

Until we have more research to draw from, we can’t know what is truly safe.

Healthy Bites appears weekly on LiveScience. Deborah Herlax Enos is a certified nutritionist and a health coach and weight loss expert in the Seattle area with more than 20 years of experience. Read more tips on her blog, Health in a Hurry!