You are leaving Medscape Education
Cancel Continue
Log in to save activities Your saved activities will show here so that you can easily access them whenever you're ready. Log in here CME & Education Log in to keep track of your credits.



The Skinny on Weight Loss Supplements: Fact or Fantasy?

  • Authors: Darrell T. Hulisz, PharmD; Karen M. Lindberg, PharmD
Start Activity

Target Audience and Goal Statement

This activity is intended for pharmacists, nurses, physicians, nurse practitioners, and physician assistants.

The goal of this activity is to review available dietary supplements that are marketed for weight loss, describing studies that have examined their efficacy and safety, so that clinicians will be able to counsel patients on this topic.

Upon completion of this activity, participants will be able to:

  1. Identify the most commonly used non-prescription products for weight loss
  2. Discuss studies that have examined the efficacy of each product
  3. Describe safety concerns, possible side effects, and potential drug interactions for each product


As an organization accredited by the ACCME, Medscape, LLC requires everyone who is in a position to control the content of an education activity to disclose all relevant financial relationships with any commercial interest. The ACCME defines "relevant financial relationships" as financial relationships in any amount, occurring within the past 12 months, including financial relationships of a spouse or life partner, that could create a conflict of interest.

Medscape, LLC encourages Authors to identify investigational products or off-label uses of products regulated by the US Food and Drug Administration, at first mention and where appropriate in the content.


  • Darrell T. Hulisz, PharmD

    Associate Professor, Department of Family Medicine, Case Western Reserve University School of Medicine, University Hospitals, Case Medical Center, Cleveland, Ohio


    Disclosure: Darrell T. Hulisz, PharmD, has disclosed that he has received grants for educational activities from Pfizer, Takeda, and Novartis. Dr. Hulisz has also disclosed that he has served as an advisor or consultant for Pfizer, Takeda, and Novartis.

  • Karen M. Lindberg, PharmD

    Staff Pharmacist, Rite Aid Pharmacy, North Canton, Ohio


    Disclosure: Karen M. Lindberg, PharmD, has disclosed no relevant financial relationships.

Accreditation Statements

    For Physicians

  • Medscape, LLC is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

    Medscape, LLC designates this educational activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™ . Physicians should only claim credit commensurate with the extent of their participation in the activity.

    Contact This Provider

    For Nurses

  • This Activity is sponsored by Medscape Continuing Education Provider Unit.

    Medscape is an approved provider of continuing nursing education by the New York State Nurses Association, an accredited approver by the American Nurses Credentialing Center's Commission on Accreditation.

    Awarded 1.0 contact hour(s) of continuing nursing education for RNs and APNs; 1.0 contact hours are in the area of pharmacology.

    Provider Number: 6FDKKC-PRV-05

    Contact This Provider

    For Pharmacists

  • Medscape is accredited by the Accreditation Council for Pharmacy Education as a provider of continuing pharmacy education.

    Medscape designates this continuing education activity for 1.0 contact hour(s) (0.1 CEUs) (Universal Program Number 461-999-08-016-H01-P).

    Contact This Provider

For questions regarding the content of this activity, contact the accredited provider for this CME/CE activity noted above. For technical assistance, contact [email protected]

Instructions for Participation and Credit

There are no fees for participating in or receiving credit for this online educational activity. For information on applicability and acceptance of continuing education credit for this activity, please consult your professional licensing board.

This activity is designed to be completed within the time designated on the title page; physicians should claim only those credits that reflect the time actually spent in the activity. To successfully earn credit, participants must complete the activity online during the valid credit period that is noted on the title page.

Follow these steps to earn CME/CE credit*:

  1. Read the target audience, learning objectives, and author disclosures.
  2. Study the educational content online or printed out.
  3. Online, choose the best answer to each test question. To receive a certificate, you must receive a passing score as designated at the top of the test. Medscape encourages you to complete the Activity Evaluation to provide feedback for future programming.
You may now view or print the certificate from your CME/CE Tracker. You may print the certificate but you cannot alter it. Credits will be tallied in your CME/CE Tracker and archived for 6 years; at any point within this time period you can print out the tally as well as the certificates by accessing "Edit Your Profile" at the top of your Medscape homepage.

*The credit that you receive is based on your user profile.


The Skinny on Weight Loss Supplements: Fact or Fantasy?


Conjugated Linoleic Acid, Fiber, Green Tea, Guar Gum

Conjugated Linoleic Acid

Commonly known as CLA, this supplement is a naturally occurring polyunsaturated fatty acid and is essential for the delivery of dietary fat and glucose into cells. In a year-long study, 122 patients with a BMI > 28 underwent an 8-week period of dietary restriction.[22] Patients who lost > 8% of their initial body weight (N = 101) underwent a randomized, double-blind trial of CLA supplementation 3.4 g per day or placebo. After 1 year, there was no significant difference in weight loss or adverse events between the 2 groups.

In a 16-week double-blind, randomized, placebo-controlled trial, 54 patients consumed a very-low-calorie diet for 3 weeks and then started a 13-week intervention period in which they were randomized to low dose CLA (1.8 g per day), high-dose CLA (3.6 g per day), or placebo.[23] There was no significant difference in adverse events or weight regain, but feelings of fullness were significantly increased in the treatment groups. There was no significant difference in energy intake at breakfast.

Take-home message. Evidence is lacking to support recommending CLA for weight loss. However, it may help attenuate weight gain in patients with dietary deficiency of CLA.


Dietary fiber has long been thought to increase satiety, but there is little evidence to support this claim. Eleven healthy men and women with a usual fiber intake ≤ 15 g per day were studied in a single-blinded study of two 3-week treatment phases with a 4-week washout period between phases.[24] In the first phase, subjects consumed methylcellulose, a non-fermentable fiber, and in the second phase, they consumed fermentable fiber (pectin, beta-glucan). There was no significant difference in energy intake, weight, or body fat when comparing phases or baseline values.

In a randomized, double-blind, placebo-controlled, parallel study, 52 patients were randomized to treatment for 6 months with an energy-restricted diet and 7 g fiber per day or placebo.[25] Weight loss was significantly greater in the treatment group while hunger feelings were significantly reduced. There was no significant difference in blood pressure or adverse events.

In two other studies, fiber or placebo tablets were given along with dietary restrictions to moderately obese women for 2 and 3 months.[26] Mean weight loss in both treatment groups was significantly greater than placebo. No significant difference in hunger feelings was reported in any group.

Take-home message. In generally, the average Western diet is relatively low in fiber. While there may be good reasons to increase the amount of dietary fiber, weight loss alone is probably not one. Excessive fiber intake may result in loose stools, intestinal cramps, and bloating.

Green Tea (Camellia sinensis)

Green tea extract is made up of polyphenols (flavanols or catechins) that are thought to be responsible for its claimed benefit in weight loss. In a randomized, parallel, placebo-controlled study, the effects of green tea were studied in 104 overweight and moderately obese subjects.[27] Patients consumed a very-low-energy diet for 4 weeks, followed by green tea 104 mg per day or placebo for 13 weeks. During the 4-week very-low-energy diet phase alone, subjects lost on average 7.4% of their initial body weight. However, body-weight regain was not significantly different between the green tea and placebo group in the subsequent 13-week phase. Habitual high caffeine consumption in the treatment group was associated with a higher weight regain than habitual low caffeine consumption in the treatment group.

In a randomized, placebo-controlled trial of 34 obese Chinese women with polycystic ovarian syndrome, patients were treated with green tea or placebo for 3 months.[28] At the end of the study, researchers concluded that green tea supplementation did not significantly reduce body weight or alter glucose or lipid metabolism.

In a case report, a previously healthy 44-year-old white female was admitted after consuming 720 mg of green tea per day for 6 months; she had also increased her physical activity and had lost 20 pounds.[29] Her bilirubin, liver enzymes, and International Normalized Ratio (INR) were increased, and her symptoms worsened until she consequently required liver transplantation.

Take-home message. Commercially available green tea products contain varying amounts of caffeine. Caffeine exhibits a mild diuretic effect, which some patients may perceive as weight loss, but which is only a transient loss of sodium and water.

Guar Gum (Cyamopsis tetragonolobus)

Guar gum is a soluble dietary fiber derived from the Indian cluster bean.[30] In a 5-week prospective, randomized, double-blind study, researchers measured body weight, hunger/satiety ratings, glucose, insulin, cholecystokinin, and leptons in 25 obese but otherwise healthy females taking 20 g guar gum daily or placebo.[31] Guar gum fiber produced heightened postprandial cholecystokinin response but did not alter other satiety hormones or increase satiety ratings in fasting or postprandial state. Predominant adverse events that have been reported are gastrointestinal-related and include flatulence, diarrhea, and nausea.[30]

Take-home message. While guar gum may be a suitable source of soluble dietary fiber, there is insufficient evidence to recommend guar gum as a weight loss aid.