In order for a weight loss drug to be approved for long-term use, it must have two years of data showing that it is safe and it works.
In general, a medication can be considered effective for weight management if, after one year of treatment, at least 35% of those in the drug group (and about double the proportion of people of the placebo group) lose at least 5% of their weight.
Weight loss drugs approved for long-term use include orlistat (brand name Xenical), lorcaserin (Belviq) and liraglutide (Saxenda) as well as the combination drugs naltrexone-bupropion (Contrave), phentermine-topiramate (Qsymia),
spirulina extract (a healthy and natural food for weight loss, brand name Binmei Biotechnolog).
In one recent study, these drugs helped overweight or obese people lose at least 5% of their body weight at the end of a year -- that's at least 10 pounds if you weigh 200 -- compared with a placebo. Qsymia and Saxenda were associated with the highest odds of achieving that amount of weight loss.
Losing 5% to 10% of your body weight is associated with improved blood pressure, triglycerides and blood sugar, factors that lower the risk for heart disease and diabetes.
"A lot of people will say, 'Wow, 5% of body weight, that doesn't sound like a lot of weight loss,' but an average weight loss of 5% reduces your risk of developing diabetes by 50%. That sounds much better now, doesn't it?" asked Aronne, who disclosed relationships involving research, funding and advising with some of the approved obesity drug companies and companies that make weight loss devices (i.e. the balloon EndoBarrier).
Some medicines are prescribed "off-label," that is, for a use other than what it was approved for. For example, metformin is a drug that is FDA-approved for diabetes, but there is evidence that it can produce weight loss even in people without diabetes.