Weight Loss Medication: When, Why & Which One?

Taking a medication for weight management is not nearly as simple as it may sound.  This is illustrated by the vast number of people who have taken a medication for weight loss and have been disappointed by the results and the fact that the most commonly used one today (phentermine) has been approved since 1959 and yet the epidemic of obesity is still increasing and only approximately 1-2% of people with the disease is receiving treatment. Pharmacotherapy (FDA approved medications) for weight management are an important tool, but they must be selected and used appropriately and as part of a comprehensive approach, or the outcome is typically not what the individual had expected.  Today’s blog is a very brief survey of when and why a medication may be used and what is currently available. This is only to be used as a place to start a conversation with a physician and not to be taken as medical advice, of course, as individual circumstances and health conditions vary. 


Almost always, when I am meeting with a person, s/he has already engaged in some sort of non medical approach to diet and exercise. Typically, they will say they have tried multiple diets on their own or multiple programs. They may say they have tried everything else and this is their last stop before either bariatric surgery or giving up. I am careful to take a detailed history of what a person has already tried so that I do not tell them to try the same thing they have already done and it has not worked. So, the following circumstances assume a person has already been trying to lose weight on their own in some fashion. Sometimes, people will blame themselves if they have not followed a program perfectly and think that means that they have not really “tried” a certain diet. But, if a program or diet is not tolerable, then that does constitute an adequate trial.  I consider using an anti obesity medication in a person with a BMI> 27 with a medical condition related to excess weight or a BMI>30, when one or more of the following applies:

- There is hunger, cravings, lack of satiety, or food withdrawal, binge eating, or night eating symptoms, either during weight loss or during weight regain prevention (“maintenance phase”).

- There is "incomplete" weight loss (i.e. weight loss plateau before clinical health goals or weight goal is met).

-There is weight regain after reaching goal weight, defined as 25% or more of the weight lost or 10% or more of total body weight (this happens for many reasons, even after bariatric surgery).

- There is a history of weight cycling, which can indicate a strong metabolic adaptation to weight loss.

Once the decision is made to start a medication, its continued use should be reassessed over time. More recently approved medications are all studied for at least 52 weeks, as opposed to historic medications studied for 12 weeks. So, there is no specific time after which they need to be stopped. Rather, it is a clinical decision to be made individually. But, if and when they are withdrawn, it is important to have a plan in place to prevent weight regain by other means. 


When I discuss medication for weight management, one of the common questions I get is different ways of people asking why they may need a medication for weight management.  To answer this, the most important thing is to "unlearn" what we have been conditioned to believe already: that weight is just "calories in, calories out" and that it is simple to just balance energy expenditure with energy intake. To do this, I ask a person to use these two frames of reference:

Do you know someone who can eat whatever they want and not exercise much and still does not seem to gain much weight, or a person who seems to eat one meal a day and yet does not lose weight?

If someone has a different chronic disease related to physiology, like high blood pressure, that was not controlled with a low salt diet, exercise, and avoiding alcohol and stress, would you think it reasonable that they take a medication as well to treat their high blood pressure, while they were also doing those health lifestyle things?

For most people, they are able to relate to the fact that not all people have the same metabolism, so it must be more complex than a simple math equation, and that taking medication as part of a healthy lifestyle makes sense to manage a chronic health condition to prevent complications. 

Which One?

While there are many over the counter supplements and many historic medications for treating weight, currently there are three FDA approved anti obesity medications available. They each work differently and have different warnings, contraindications and potential side effects. They also each is known for working on the three different causes of excess weight.  This is a brief summary to start a conversation depending on what kind of excess weight or relationship with food you may have:

High Hunger or Fat Mass Disease

If you have high hunger, or a BMI over 40, then you may benefit from phentermine and/or topiramate. This medication combination suppresses appetite, increases metabolic rate, and is catabolic to both excess fat and the excess muscle that tends to accompany a BMI over 40. To take this medication, you must have a good cardiovascular health, have no chance of getting pregnant, have no kidney disease and no history of kidney stones, as a partial list of things to consider. 

Food Cravings / “Emotional Eating”

Cravings are intrusive thoughts of food, typically that are not physical hunger; therefore, an appetite suppressant is not effective. Cravings, also sometimes called "emotional eating" is likely mediated by different neurotransmitters than physical hunger. Bupropion/naltrexone is known for addressing this scenario. To take this medication, you must have never had a seizure, be not taking any opiates, not be at risk for cardiovascular stimulants, as a partial list of things to consider. 

Insulin Resistance

Insulin resistance is caused by high insulin levels, which can cause weight gain and more insulin resistance, in a vicious cycle that ends in Type 2 Diabetes Mellitus. You can tell if you have insulin resistance by a high waist circumference, a high fasting blood sugar, a triglyceride to HDL ratio over 2.5, or a HA1c over 5.6.  Liraglutide is the currently approved anti obesity medication in this class, although additional options are likely to be approved soon, such as semaglutide. These medications are also used to treat Type 2 Diabetes. To take this medication, you must have not had a personal or family history of medullary thyroid cancer, a personal history of pancreatitis, a chronic unexplained gastrointestinal condition, as a partial list of things to consider. 

Remember, anti obesity pharmacotherapy is only a small part of the comprehensive evaluation of a person's weight. The first step is evaluating for underlying causes and contributing factors. Pharmacotherapy is only one potential part of a treatment plan. It needs to be selected and used by a physician with the appropriate training, experience, and individual clinical consideration, joint medical decision making, longitudinal follow up, and periodic reassessment for the best safety and long term efficacy. But, when properly selected, the right medication at the right time as part of the right program can be that "missing piece" that makes all the other pieces fall into place.

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