OTCs Today
Mary Warner
Although GLP-1 receptor agonists are becoming more and more popular for weight loss, many patients are still looking for a nonprescription way to shed excess pounds. Numerous supplements are marketed for quickly burning fat, but only Alli, a half-strength OTC version of prescription orlistat (Xenical), is FDA-approved for weight loss.
Alli, sold as 60-mg capsules, is approved for use in adults 18 and older who have a BMI of 25 or more, while Xenical is available as 120-mg capsules and approved for use in adults with a BMI of 30 or more or a BMI of 27 to 30 with other health risk factors such as high BP or diabetes. Both Alli and Xenical are meant to be used as part of a weight-loss plan, along with a low-calorie, low-fat diet and regular physical activity.
How does orlistat work?
Orlistat promotes weight loss by decreasing the amount of dietary fat absorbed in the intestines. It blocks the activity of lipase, the enzyme found in the digestive tract that breaks down dietary fat so that it can be used or stored for energy. When orlistat is taken with a meal, about 25% of the fat consumed isn’t broken down and is instead passed through the body and excreted in bowel movements.
The manufacturer of Alli recommends taking one 60-mg capsule within an hour of a fat-containing meal up to 3 times a day. Daily fat intake should be spread over the course of 3 meals and should be no more than 30% of the total calories consumed in each meal, preferably about 15 g fat/meal. Patients should be aware that if they eat a meal with more fat than recommended, they will likely experience more severe digestive adverse effects. Patients should also take a multivitamin before bed to replace the fat-soluble vitamins (b-carotene and vitamins A, D, E, and K) that may be blocked by orlistat.
Weight loss with orlistat is modest, resulting in an average of 5 to 6 pounds more lost over the course of a year than with diet and exercise alone. And use of orlistat is associated with adverse effects related to the undigested fat passing through the digestive system, including stomach pain, an oily anal discharge, excess gas, and urgent bowel movements, though these effects generally lessen over time. Headaches, back pain, and common cold symptoms have also been noted with orlistat use.
Patients should not take Alli if they are taking medications for diabetes, thyroid disease, heart disease, or HIV, and if they have a history of gallbladder problems, kidney stones, pancreatitis, or irritable bowel syndrome, or are pregnant or breastfeeding. Cyclosporine should not be taken with orlistat.
Thermogenic supplements
Thermogenic (heat producing) supplements are marketed as an easy way to burn fat. While there is evidence that they can reduce appetite and boost metabolism and fat burning, the effects are relatively small and the safety of some of the ingredients in the supplements has been questioned.
Caffeine is often the main ingredient in commercially available thermogenic supplements due to its ability to increase resting energy expenditure as well as augment fat oxidation and fatty acid turnover. However, because caffeine’s effects on metabolism are relatively small, caffeine supplements are unlikely to make an impact on body weight.
Other thermogenic or herbal ingredients, including L-carnitine, capsaicin, green tea leaf extract, guarana seed extract, and bitter orange are often included with caffeine in an effort to boost metabolism. However, it’s unclear whether these effects are significant enough to help people lose weight or body fat. In addition, stimulant-based supplements often raise concerns for the potential negative impact on heart rate and BP.
Capsaicin, one of the more popular ingredients in thermogenic supplements, stimulates the release of adrenaline, which speeds up metabolism and causes the body to burn more calories and fat. Studies have shown that use of capsaicin supplements can boost metabolism by about 50 calories per day, which could lead to significant weight loss over time, but there is also evidence that the body can adapt to capsaicin, reducing supplement effectiveness over time.
Bitter orange, another popular ingredient in thermogenic supplements, contains synephrine, a natural stimulant similar in structure to ephedrine. Studies have shown that 50 mg of bitter orange can increase metabolism and burn an additional 65 calories per day.
Most patients tolerate thermogenic supplements well, but they can cause unpleasant adverse effects, including nausea, constipation, abdominal pain, and headache. They can also lead to a slight increase in BP.
What to tell your patients
Ensure patients understand that most weight loss occurs within the first few months of supplement use. Advise patients of the potential adverse effects of thermogenic supplements and that supplements containing more than 400 mg of caffeine should be avoided since they can cause heart palpitations, anxiety, headache, restlessness, and dizziness. ■