Medication Side Effects: Doctor I’m Gaining Weight!

One of the biggest challenges we face in the field of psychiatry is medication adherence. A large portion of the people fail to get better either because they do not start the medication, or do not take it as prescribed. One of the most common reason cited by patients for stopping medication is weight gain. In this article I will detail the approach I take to weight management for patients on psychiatric medications. 

Initial Visit: 

Weight management is a discussion that should happen between the patient and clinician at the first meeting. It’s important to use primary prevention (preventing the onset of weight gain) if possible. We always obtain some objective measures such as height, weight, and calculate the BMI on the initial visit and subsequent visits. Additional tests that may be ordered include HBA1C, fasting blood glucose, and lipid profile. This is where I will take the opportunity to discuss the importance of diet and exercise. For people with little diet or exercise experience I will keep the information very basic. The discussion will center around eliminating processed foods, calorie containing beverages, increasing fruit and vegetable intake, and making good choices when shopping at the food store. I have several handouts with food choices on them that help guide the patient when making food choices at the grocery store. I also recommend patient’s keep a food diary or track their food intake on a mobile app such as my fitness pal. This will help us to understand more about the patient’s eating habits and identify potential areas for improvement. I will build on diet interventions and monitor progress with the food diary or app at each visit. I do not recommend a specific diet, as it’s far more important for the patient to pick something they can be consistent with, and there are multiple ways to achieve weight management goals. At this time the closest diet we have that I’m comfortable recommending is the Mediterranean diet. There is some good evidence that the Mediterranean diet can have an antidepressant effect which is an added bonus.

Exercise

Exercise is the next area to address. I like to ask some screening questions about what type of physical activity the patient engages in, and how much experience they have with fitness/athletics. I will then ask them to track their exercise over the subsequent weeks prior to returning for follow up visit. On the initial visit I will recommend they begin a basic walking program of at least 30 minutes per day preferably seven days per week. This is a simple thing to incorporate on a daily basis, and does not require any special equipment or gym membership. We can improve on this routine and incorporate resistance training on a case by case basis. 

Medication Choice

The next step in the process is to make a medication choice that limits the potential for weight gain. Most psychiatric medications cause weight gain. This is an unavoidable fact. Avoiding the use of medications with the highest propensity of weight gain including Clozapine, Olanzapine, and Mirtazapine is good planning on the physician’s part. It’s important to note that it’s not always possible to avoid these medications. Medications such as Aripiprazole which are considered to be weight neutral, from clinical experience are not weight neutral at all. It’s important for the clinician to make good choices if weight gain is a potential issue that will interfere with treatment.

Medication For Weight Management

My last line of defense against weight gain which often comes too late is medication management. I like to start with Metformin extended release 500 mg daily after the largest meal. This is to test the patient’s tolerance for the medication. The goal is to titrate to 2000 mg/day in divided doses. A B12 level should be checked once per year as Metformin has been known to reduce levels. There is evidence in the literature from a Meta-analysis of all RCTs supporting the use of Metformin for antipsychotic induced weight gain. The important thing to remember is to start the medication at the earliest signs of weight gain, or even before the onset of weight gain in high risk patients. The patients most likely to benefit are those who are younger, more recently started on antipsychotics, overweight but nor obese, and those that had rapid weight gain. 

The second medication I will talk about is Topiramate There is evidence from RCTs to support the use of Topiramate for antipsychotic induced weight gain. There is greater weight loss with Topiramate over placebo, with a mean decrease of 2.8 kg. The effective dose for the medication is 100 to 200 mg/day depending on the patient’s tolerance. Getting to an effective dose can often take some time with this medication.

Final Points

Weight management discussions begin day one when medications are going to be used. Prevention is the first line option with lifestyle modification including diet and exercise. Medication choice also plays a big role. When initiating medication being mindful of the propensity for weight gain, and using medications that are weight neutral if possible, can help. If these measures fail, there are a few options backed by research evidence which can be used but I believe lifestyle modification is the best option. 

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