Measuring Obesity on Antidepressants

Judith Wurtman Health Guide
  • If you have been a normal weight all your life and find yourself gaining weight while on antidepressants, how will you know if or when your medication may make you obese? It is doubtful that your doctor will tell you; he or she usually does not have a scale in the office or a height/weight chart on the wall. The well-known side effect of antidepressant-associated weight gain is often not even mentioned by the prescribing psychotherapist lest it discourage the patient from starting or continuing the medication.


    Ideally, preventing the weight gain at the beginning of treatment should be part of the management of the emotional disorder. As we mention in our book, The Serotonin Power Diet, it is not difficult to follow a dietary regimen that eliminates the overeating and cravings most antidepressants cause within weeks of starting treatment. However, in most cases, weight gain is discussed only when the patient brings it up and this may be only after a substantial amount of weight has been gained.  How do you get your physician to take your concern seriously? One way is to document that the pounds you have added as a result of the medication.

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    A client at our weight-loss practice told me the following. "I would go into my shrink's office and show her how tight my skirt was or how much my thighs were bulging in my jeans. She would shrug, tell me that I looked healthy and not to worry about it. But I was worried and found a BMI chart on the Web that put me into the obese category. The next time I saw my doctor, I showed her the chart and told her my weight was making me unhealthy and she had to do something about it."


    As this client found out, she had to figure out herself whether her weight gain made her obese and as a result more likely to develop type II diabetes, heart disease or orthopedic problems that often follow from substantial weight gain. But these days, looking at a chart or a scale may not be the best way of determining obesity.

    There are three types of measurements used to determine if someone is of normal weight, or overweight or obese. The simplest and the one around the longest is the height /weight chart. Pediatricians use such charts from birth on and your doctor uses the same charts, adjusted for age. Weight-loss organizations and health clubs use them, too. The charts are generous in the range of weight you can have for a given height and make allowances for age. If you are over 50 you are allowed to weigh more for the same height. But as a friend told me, "I am shrinking and my former weight when I was two inches taller is no longer healthy."


    A seemingly more sophisticated method using your height and weight is called the BMI or body mass index.  To figure this out, you multiply your weight in pounds by your height in inches squared (height x height). Then you multiply this figure by 703 to convert it to a metric number, as the BMI is not based on inches and pounds. Most surveys on the percent of obese people in a population are based on the BMI.  If you try this calculation then the following chart will tell you whether you are underweight, ideal, overweight or obese.


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    Below 18.5 underweight

    18.5 to 24.9 ideal

    25.0 to 29.9 overweight

    30.0 and above obese


    The problem with this method is that your weight consists of more than just the fat in your fat cells. You already know that water retention can add or subtract pounds to the scale. But did you know that your bones and muscles contribute to much of your weight?  Bones are more dense than muscle and muscle is more dense than fat.  A frail 83 year-old who has lost most of his muscle mass and has thinning bones may have a lower BMI than someone with large bones and well- developed muscles.  In fact, years ago when we did a study among women smokers, we found to our astonishment that their BMIs put them in the ideal or even underweight category. But when they had a body scan of their bones and fat mass, it turned out that most of their weight was from fat; they had very little muscle and their bones were thin.


    The best way of figuring out whether you are falling into an unhealthy weight because of your medication is to use a tape measure. These days something called the waist-hip ratio is being used to determine whether the size and location of your fat stores are normal or likely to lead to diabetes or cardiovascular disease. You don't need a scale for this measurement, and it will not be affected by whether you just drank a large glass of water. Stand in a relaxed pose and measure your waist at its smallest place, which is at your navel. Then measure your hips at their largest spot, which is over your buttocks.  Divide your waist measurement by your hip measurement. A ratio above 0.8 for women and 0.95 for men is considered unhealthy and associated with obesity-related diseases. 


    The reason for concern if your ratio is higher than recommended is because fat stored over your abdomen has been found, in many studies, closely associated with those diseases that affect the quality of your life and may shorten it.


    It would be a good idea to make baseline measurements before you start on your medication or if you are switching from one medicine to another. If you find the ratio going up, then bring it to the attention of your physician. Pop a tape measure in your purse or briefcase in case your doctor wants to verify the numbers on you (or check his or her own measurements).


    Fortunately, you do not have to go off your medications to reduce the size of your waist. Simply eating therapeutic doses of carbohydrate that boost the appetite- suppressant effects of the brain chemical serotonin will allow you to eat less and not feel hungry. Add an exercise regiment and you can turn back into your formerly thin self.

Published On: July 28, 2009