Why Lorcaserin And Other Weight Loss Drugs Fail To Deliver

How Does Lorcaerin Work?

lorcaserin drug for weight lossHumans and other animals produce serotonin, a protein hormone that plays a role in appetite. It binds to specific cell receptors including the 5HT2C serotonin receptor and thus regulates hunger. Lorcaserin is a weight loss drug that was designed to mimic the action of serotonin and bind to the 5HT2C receptor to suppress appetite. On the outset this seems logical because if a person doesn’t feel hungry they’ll feel less inclined to eat. But nothing is ever so simple.

There was a serious flaw in Arena’s research. The problem with lorcaserin’s studies is that the drug trials were not representative of the general population. After initial testing, Arena selected just over 7000 candidates for two phase 3 trials of lorcaserin’s efficacy as a weight loss drug.

The BLOOM Trial for Lorcaserin?

BLOOM which is an acronym for Behavioral Modification and Lorcaserin for Overweight and Obese Modification was the first phase 3 trial. This study took place over a two-year period and involved 3182 overweight or obese males and females who were randomly assigned to either a lorcaserin group (receiving 10 mg twice a day) or a placebo group (receiving an inert substance that doesn’t do anything for or to the body).

BLOOM’s had two main objectives, the was to assess lorcaserin’s effect on weight over the course of a year. The second top objective was to determine if patients who received lorcaserin could keep the weight off during the second year. In other words, to test whether or not lorcaserin would cause weight loss and help patients keep it off. *

BLOSSOM Trial for Lorcaserin

The company also conducted a second phase 3 trial called BLOSSOM for Behavioral Modification and Lorcaserin Second Study for Obesity Management. This study was only one year in duration and involved 4008 overweight or obese males and females. This group also had an objective which was to determine if lorcaserin could cause weight loss over the course of one year. There was a difference between the BLOOM and BLOSSOM studies. BLOSSOM patients were randomly assigned to one of three groups: a group receiving 10 mg of lorcaserin twice a day; a group receiving 10 mg lorcaserin once a day; or a placebo group.

But the company immediately made a serious error because the sample sizes were far too small to give a clear picture of how lorcaserin would affect the health of people who took the drug. In other words there is no way to know if lorcaserin is safe for human use. To have an accurate picture they should have taken a much larger sample size. And according to the FDA review, the BLOSSOM study had to be revised because it was initially designed for less than 4000 candidates.

Although it is scientifically impossible to have perfect confidence in the outcome of any study i.e. there will always be uncertainties, unintended consequences and side effects,  large sample sizes provide considerable data, and increases the accuracy of the results. Only Arena knows why they selected a relatively small population.


I hold a degree from one of the top ranked research universities in the United States. I am the administrator and publisher of Living Fit, Healthy and Happy which is a family-friendly health and wellness website with articles on fitness, anti-aging, obesity, diabetes, eating disorders, cardiovascular health and many other health related issues. Publishing fitness and healthy living blogs is my way of getting the word out to the public about the benefits of a healthy lifestyle. So on Living Fit, Healthy and Happy I write articles using the pen name "healthy_blogging". I also re-publish the articles of other authors whom I deem to have scientific merit and serve the public interest. In my free time, I enjoy physical fitness, outdoor activities, reading of fiction and nonfiction material, listening to music and spending time with family and friends.

12 thoughts on “Why Lorcaserin And Other Weight Loss Drugs Fail To Deliver

  • November 18, 2010 at 4:11 pm

    Lactulose is a potent laxative. There will be diarrhea, but that is to be expected. Normal side effects are bloating, belly cramps, etc. For patients in advanced kidney failure, things get a bit tricky, as diarrhea means excretion of potassium. Because of that hypokalemia )low potassium) and hypernatremia (high sodium) can ensue. These electrolytes need to be measured carefully in such patients and whoever prescribed the lactulose must know that patient has these health problems. Hope that helps…

  • October 28, 2010 at 12:23 pm

    Hello Jarret and Doug,

    I’m excited by all the buzz that my article has been generating. It’s an important topic and I’m happy for the opportunity to guest post here and that so many people find the article informative.

    I agree that Arena failed to because they only looked at one aspect of obesity. Until the pharmaceutical industry helps consumers address the root causes of the problem, they will never be successful in helping the masses sustain long term healthy body weight.


  • October 27, 2010 at 8:37 am

    Joseph, thanks for the great article on weight loss pills and Locaserin, in particular. 370 retweets is definitely the most we’ve ever seen here at Hive Health Media.

  • Pingback: Why Lorcaserin And Other Weight Loss Drugs Fail To Deliver – Hive Health Media (blog) | Dr. Simon Ourian

  • Pingback: Red Hot Metabolism | Fix A Broken Metabolism

  • Pingback: How much weight do you have to lose before you start seeing it? | Fad Diets That work

  • Pingback: Do Miracle Weight Loss Supplements Really Help You Lose Weight | eConsumerAlley.com

  • Pingback: Why Lorcaserin And Other Weight Loss Drugs Fail To Deliver :Weight Loss Blog

  • Pingback: Why Lorcaserin And Other Weight Loss Drugs Fail To Deliver – Hive Health Media (blog) | Orange County Weight Loss Surgery

  • Pingback: Thrice- The Weight | My Health Bulletin - General Health Information

  • Pingback: Ahead of the Bell: Arena Pharmaceuticals – BusinessWeek | newzbuff.com

  • October 26, 2010 at 7:51 am

    One significant hurdle facing any and all obesity drug manufacturers is that obesity is a multi-faceted problem

    Brain chemistry, hormones, genetics, epigenetics, lifestyle, social pressure, advertising, etc….

    So, when a drug like Lorcaserin takes a focused approach (serotonin) to solve a multi-faceted problem, I believe that they are doomed to failure.


Leave a Reply

Your email address will not be published.