American Association of Clinical Endocrinologists Annual Meeting
American Association of Clinical Endocrinologists Annual Meeting
May 16, 2018
3 min read

Communication key to safe use of dietary supplements for weight loss

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Laura Shane-McWorter
Laura Shane-McWhorter

BOSTON — U.S. adults report help with losing weight as a top reason for taking dietary supplements, and more than one-third of those who have made a serious weight-loss attempt report consuming vitamins, minerals, herbal or botanical products, amino acids or other substances as a weight-loss strategy, according to a presenter here.

“Patients may be using these products, and communication is critical,” Laura Shane-McWhorter, PharmD, BCPS, BC-ADM, CDE, FASCP, FAADE, professor in the department of pharmacology at the University of Utah College of Pharmacy, told Endocrine Today. “It is important to have a conversation with patients to find out what they are using and why, and try to provide evidence-based information to them — especially the possibility of adverse effects or drug interactions.”

Although many patients assume they are safe, products marketed as dietary supplements may contain substances not disclosed on ingredients lists, including laxatives, diuretics, thyroid hormones, prescription weight-loss drugs — including sibutramine, which has been withdrawn from the market — and other agents that may counter side effects, such as beta-blockers, which may mask increase in heart rate. Even unadulterated supplements can have adverse effects and interactions with other drugs.

Health care providers should talk with patients nonconfrontationally about supplement use, Shane-McWhorter said, encouraging them to examine labels and look up unfamiliar substances and emphasizing that these products are not FDA approved. “Science over anecdote” should be the theme when discussing evidence, she said.

During her presentation, Shane-McWhorter reviewed the safety and efficacy evidence for several dietary supplements popular with adults seeking to lose weight.

Alpha lipoic acid (thioctic acid)

Uses/mechanism of action: Decreases oxidative stress, increases insulin sensitivity, decreases appetite.

Side effects/interactions: Gastrointestinal discomfort, urticaria. May affect thyroid function.

Bottom line: This agent has been used for many years in Germany to treat peripheral neuropathy, and its use is backed by several randomized controlled trials. Side effects and drug interactions are not serious. Evidence of effect on weight loss is emerging.

Flax seed

Uses/mechanism of action: Plant-derived omega-3 fatty acid decreases oxidative stress, may increase beneficial gut microbiota; fiber increases satiety.

Side effects/interactions: GI discomfort. May increase effects of antihypertensive, diabetes and lipid-lowering medications. May increase bleeding risks if taken with warfarin.

Bottom line: Use of flax seed for weight loss has not been studied in large randomized controlled trials. Lower-quality studies have shown greater weight loss.

Garcinia cambogia

Uses/mechanism of action: Decreases fatty acid synthesis and glycolysis, which increases satiety, and increases serotonin release, which may increase feelings of well-being.

Side effects/interactions: Headache, GI discomfort, cough. May be hepatotoxic. Interacts with diabetes medications and selective serotonin reuptake inhibitors and perhaps with statins.

Bottom line: Long-term safety and benefits are unknown due to lack of studies. A more recent study showed an increase in weight with this agent. Often combined with other agents.

Green tea (Camellia sinensis)

Uses/mechanism of action: Contains catechins and caffeine. Increases calorie and fat metabolism, decreases lipogenesis and fat absorption and suppresses appetite.

Side effects/interactions: Headache, dizziness, increased blood pressure, GI discomfort. May be hepatotoxic. Contains vitamin K and interacts with warfarin. May interact with antihypertensive medications.

Bottom line: Study results exploring an association with weight loss have been mixed. Hepatic damage has been correlated with consuming green tea on an empty stomach and in combination products. Health care providers should monitor live function test, BP and effects of other medications.

Human chorionic gonadotropin (HCG)

Uses/mechanism of action: May increase metabolic rate.

Side effects/interactions: Possible deep vein thrombosis, pulmonary embolism. May increase anxiety, thyroid dysfunction, ovarian hyperstimulation, testicular tumors. May decrease efficacy of anticoagulant drugs.

Bottom line: A single small study showed weight loss with HCG plus very low-calorie diet.


Uses/mechanism of action: Gut microbes allow calorie extraction from indigestible polysaccharides, decrease inflammation. Probiotics compete in the gut with unfavorable microbes associated with obesity.

Side effects/interactions: Increased GI gas, diarrhea and constipation. May contribute to antibiotic resistance. May interact with antibiotic and antifungal therapies.

Bottom line: What constitutes a healthy microbiome is currently unknown, as are which types of microbes are beneficial for which patients in what doses and for how long.

“There are so many different products that are being used,” Shane-McWhorter said. “As clinicians we must stay up-to-date on the published information.” – by Jill Rollet


Shane-McWhorter L. What’s up with all these supplements? Presented at: AACE Annual Scientific and Clinical Congress; May 16-20, 2018; Boston.

Disclosure: Shane-McWhorter reports she has received author royalties from the American Diabetes Association.