Medical Minute: Understanding Weight Loss Drugs

In the last month I’m sure in some capacity youmay have heard of a new weight loss drug being released to the market: Saxenda.  It has gotten a lot of hype due to the fact that is incredibly expensive.

It has also gotten people asking- are there other options? What do weight loss drugs do?

These are prescription weight loss drugs – and they needed to be treated like a medicine – not a curative magic pill.

Additionally these meds can have significant side effects that need to be taken into consideration, especially as they are used long term.

It’s also important to remember that “obesity” itself, is not as cut and dry as “calories in vs calories out”.  We know a lot more about obesity than we did even 2, years – let alone 5-10 years ago.  Obesity is considered a chronic disease- it is complex, and it develops from interaction between someones genetic makeup, and the environment. Obesity itself is considered a disease, however it’s also considered causal of other disease secondary to hormone imbalances and/or inflammation.

complications of obesity

We also now know that fat cells are metabolically active tissue, and an increase in visceral fatty tissue (versus subcutaneous adipose tissue – which is not metabolically active) can lead to increases in  not just ectopic fat on our organs (liver, muscle, heart) but also various inflammatory markers, and hormone secretions.  This happening over a long period of time is thought to play a role even in our brain, in how our brain processes information.

In fact we all have fat that secretes a hormone – leptin.  The secretion of leptin should tell the brain “ok, we have adequate fat stores, so everything is good- we don’t need anymore”.  However, in both rats and in humans, those who are leptin deficient – tend to have VERY unhealthy weights!  So this is one [potential] mechanism of obesity.

Again remember – hunger and satiety (fullnes) are hormone driven, and are processed in the brain.  There are a lot of moving pieces so understanding that there is a neurological component is very important to understanding weight loss medications.

These are the weight loss drugs (approved by the FDA for weight loss) that I see the most in practice:


(Lorcaserin)> This activates the serotonin 2C receptor in the brain (this decreased hunger, and increases satiety).  **Side bar: I describe the feeling of satiety as “comfortable fullness”, when you recognize you have had enough to eat, and do not eat past that point.

Annual expected cost: $1743



(Phentermine + Topiramate) > This is a combination drug, the phentermine affects the central release of norepinephrine, while topiramate augments the activity of GABA (neurotransmitter) to reduce appetite and food cravings

Phentermine can have quite the side effects, so monitoring changes in behavior, and mood is important with starting Qsymia.  You will want to avoid excess caffeine, and decongestants with Qsymia, or just phentermine itself.

Annual expected cost: $1336



(Bupropion + Naltrexone) > This is another combo drug – the bupropion (wellbutrin) is appropved to treat depression and seasonal affective disorder, and as an aid to smoking cessation.  Naltrexone is approved to treat alcohol and opioid dependence.  Bottom line this drug works in addition centers of the brain.

Contrave does have programs in place and discount cards to allow a reduction in cost



(Liraglutide) > This is an injectable weight loss drug, it is in a class of drugs called GLP-1 Receptor agonists.  It has the same active ingredient as a diabetes treatment medication called Victoza- so they should not be used at the same time.

Unlike the other weight loss drugs listed above, Saxenda is predominantly working in the gut.  GLP-1’s mutliple physiological effects make it a nice candidate – not just for weight loss but also for the treatment of Type 2 Diabetes.

It stimulates insulin release, and glucagon inhibition but only when blood glucose levels are too high, and it has a very favorable impact on gastric emptying (food being emptied from stomach to small intestine) – it slows emptying down.  Leading to an earlier feeling of fullness (GLP1 tells your brain it is fuller faster).

Saxenda is easily the most expensive on the market right now – coming in around $1000 per month.  It has a hefty price tag, however it wow’d in FDA trials in terms of weight loss.


Here’s the deal: these are medications not cures, they should be used in conjuction with a physical activity regimen, and a calorically adequate diet, and should be used with patients once rapport has been built.  Once success is seen on these medications – it is very likely that if you go off of the medications, or have a significant change in your physical activity regimen, or increase your caloric intake signifcantly – weight gain will very likely occur.

It’s important to remember that people do not reach unhealthy weights by choice alone.  Yes in many cases poor nutrition and excess calorie intake are seen, and in some cases education, and coaching, and motivational interviewing can help here.

Understanding the physiology of obesity, is a huge part of helping patients see improved health outcomes and great weight loss.

**Remember, I am a dietitian, but I am probably not YOUR dieitian, and I’m not a doctor.  I’m speaking about these drugs today, to shed some light on them, and provide information.   This information is NOT a substitute for a visit to & conversation with your doctor!**


Machineni, MD MGH Weight Center, Boston > via CDR Certificate of Training in Adult Weight management Program March 20-22, 2015 presented by S. Cummings, MS, RD

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