Keeping the Pounds On: Causes of Unexplained Weight Loss

Our society is obsessed with weight, if you haven’t noticed. More than two thirds of US adults are overweight or obese, there are more diet books published than we can count, and, of course, we have the privilege of watching shows like The Biggest Loser to help keep us in line. And according to government statistics, more than 85% of people with Type 2 diabetes are overweight. So it stands to reason that much of the focus of managing Type 2 diabetes is based on reaching and staying at a healthy weight.


It’s important to note that thin people can get diabetes too, and not just Type 1 diabetes. In a 2008 study published in the journal Diabetes Care, adults age 60 to 79 years old with a body-mass index (BMI) of less than 18.5 (which is considered to be underweight) were 30% more likely to get Type 2 diabetes than adults with a “normal” BMI of 18.5 to 24.9. In a society where being thin equates with beauty, youth, intelligence, and success, there is often little sympathy or patience for people who are too thin and who desperately want to gain weight.

If you’ve struggled with losing weight and keeping it off, you know all too well how challenging that can be. People who want to gain weight often face the same kind of battle. And to have diabetes on top of that can make it doubly difficult.

First things first: identify the cause
If you have diabetes, are underweight, and would like to gain weight, it’s helpful to first have a talk with your doctor. Make sure there are no health or medical reasons for you being underweight (especially if you’ve recently lost weight without trying) such as having an overactive thyroid, a digestive disorder (such as Crohn disease), or cancer, for example. A physical exam, blood work, and other tests may be needed to rule out certain conditions. Also, don’t overlook your mental health: Being stressed, anxious, or depressed can turn off your appetite like a light switch.

Next, focus on your diabetes: uncontrolled diabetes, evidenced by constant high blood glucose levels and a high A1C level, can cause you to shed pounds and make it virtually impossible to gain weight. Why? Glucose levels that remain high for a while signal insufficient amounts of insulin, whether injected or made by your pancreas. When there isn’t enough insulin around, glucose stays in your blood and can’t get to your cells to be used for energy. The body needs fuel from somewhere, so in the absence of glucose, it starts to burn fat and muscle (burning fat can be good, burning muscle not so much).

So, if you’ve lost weight and/or are unable to gain weight AND your blood glucose levels have been running high, your first goal is to focus on getting your diabetes under better control. Doing so may mean starting on medicine (including, possibly, insulin), adding a different type of medicine to your regimen, and/or increasing the dose of a diabetes medicine that you’re already taking. And, of course, meal planning and physical activity work with your diabetes medicine to help you manage your diabetes, as well. In many cases, you may regain the lost weight once your blood glucose levels are reigned in.

Another possible cause of weight loss may be some of the medicines that you take. While the effect of medicine on weight is often very individualized, certain medicines could possibly affect your weight including the following:

• Sedatives (diazepam [brand name Valium and others])
• Antidepressants (bupropion [Wellbutrin and others], fluoxetine [Prozac and others], amitriptyline [Elavil and others])
• Antianxiety meds (benzodiazepines, buspirone [Buspar])

Diabetes medicines aren’t off the hook as far as weight loss goes, either. One example is metformin, a drug commonly used to help manage Type 2 diabetes. Metformin works by lowering the amount of glucose produced by the liver, decreasing absorption of glucose in the intestines, and increasing the body’s sensitivity to insulin. Some people who start taking metformin end up losing weight, likely due to several reasons: Metformin can blunt the appetite, and initially, may cause nausea, vomiting, and/or diarrhea (symptoms not exactly conducive to eating).

GLP-1 receptor agonists, such as exenatide (Byetta), liraglutide (Victoza), and exenatide extended-release (Bydureon) are non-insulin injectable medicines that work in several ways to help lower blood glucose: They slow the release of glucose from the liver, they slow the emptying of the stomach after eating, and they help you eat less by making you feel more full. As a result, many people who start on these medicines lose weight — obviously beneficial for someone trying to lose weight, but perhaps not so much for someone who needs to gain or at least maintain their weight.

If you have questions about side effects of any of the medicines that you take, ask your pharmacist or your health-care provider.

Next week: steps to take to help you gain weight

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  • Carol T

    Thanks, Amy, for giving us lightweights some recognition. As my A1c entered the prediabetes range, my endo put me on metformin HCL 500mg 4/day. I have since cut back to 3/day. With my decreased appetite, I lost about 7 lbs. I began drinking high (whey) protein mixed in skimmed milk at least once daily. I regained about 5 of the lbs. Recently, I was hit with intestinal flu and really bad diarrhea. Lost all the weight and down to 108.2! Am gradually working to get it back on, but it doesn’t go on quickly. Have lost muscle mass and know that I should be doing some light weight training. Down to size 2 from a 4. I am almost 69 and in good physical shape, walk almost daily, and move a lot. I noticed when I worked in long-term care and with my own mother, when elderly drop a lot of weight, it is really difficult to regain. Decreased appetitite along with taste and smell may be part of the reason. Have had lab work done, saw my doc and nothing appears out of line. Any other tips for gaining. I eat several small meals a day and can’t hold as much food as I did when I was younger. Thanks, Amy. I really enjoy your column.
    Carol T.

  • acampbell

    Hi Carol,

    It certainly can be hard to gain weight. Often, the first step is to stop losing weight, which hopefully you’ve done. It’s good that you’re eating several small meals each day. Make the most of these meals: Add a fat source whenever you can, such as oil, avocado, nuts, or seeds. These will add a lot of calories in a small volume. Since you did well with the whey protein, consider going back to that, except add it to whole milk rather than skim milk. Another option is to try a nutritional supplement like Glucerna, Ensure, or Boost. These do contain carbohydrate, but the priority seems to be gaining weight at this time; if need be, your metformin could always be increased. Also, it’s important to try and rebuild some of your muscle mass, as you mentioned. Small hand weights or a resistance band can be helpful.

  • zubaida

    I had been type 2 from last one n half yr.i lost weight now my BMI os 17.9,i wanted to gain some wt. right now my wght is 43kg and my A1c is 7.6,I am taking metformin 1000 for one day.plz tell me wht to do i regularlly do walk too.

  • roseann

    hello im like carol my doctor put me on 4 metformins 4 glizipide im losing weight lost about 20 something lbs very concerned losing it didnt my blood sugar in fact its mostly200 or over id like to gain a few lbs its hard to do ,try dont know what foods to eat i stopped 2 metformins got gassy from them hated them ,can high uncobtrolled blood sugar cause rapid weight loss

  • A. Campbell

    Hi zubaida,

    First, talk with your doctor about your weight and make sure that there is no other reason for your weight loss, such as an illness or stress, for example. Second, try to meet with a dietitian who can review your diet with you and make sure that you’re taking in enough calories. Aim to eat at least three meals each day and include small snacks in between meals. Figure out ways to add more calories to your eating plan without adding too much carbohydrate (bread, pasta, rice), which will raise blood sugar levels. Use more oil, butter, or margarine on your foods. Snack on foods like peanut butter, cheese, or nuts. Look for liquid supplements that are controlled in carbohydrate, such as Glucerna Hunger Smart or Boost Glucose Control.

  • A. Campbell

    Hi roseann,

    Sometimes people lose weight when they take metformin — this is considered to be a “side effect” of this drug. However, if you’ve stopped taking metformin, that can lead to higher blood sugars. It’s generally not a good idea to stop any medication without checking with your doctor first. Metformin can cause gassiness, but this symptom usually disappears after a week or two. Constant high blood sugars can lead to weight loss because your body isn’t able to use glucose properly for energy. As a result, you end up excreting glucose (calories) in your urine. It’s important that you let your doctor know that you’ve stopped the metformin and that your blood sugars are running over 200. Talk to him about either taking a lower dose of metformin and gradually increasing the dose, or another type of medicine to help lower your blood sugars.

  • Melissa Hughery

    My mom is diabetic and she is so skinny now and she can’t keep food down. The doctor told her to lower her insulin intake, but they didn’t give her a range on when to lower it or don’t take it all. She is sick all the time now and i don’t know what to do. What can this be?

  • acampbell

    Hi Melissa,
    Sorry to hear this. I’m wondering if she has a condition called gastroparesis, which can occur from having diabetes. There’s certainly some kind of medical issue going on with your mom and
    I’m hoping that you’ve contacted her doctor to address this. If not, please do so as soon as possible and if you aren’t getting the answers that you need, take her to another doctor who can get at the root of the problem.

  • Tobias O’Brien

    I’m trying Protein from Sci Mx. I lost 3 and a half stone over about 6 or so months, had negative CT scan, negative bloods, negative stools, negative Endoscopy. Yet when I eat I get left abdomen pain, then when I pass it through I get lower left rib pain. I live on peanut butter sandwiches and granola bars now. I have tried eating a pack of hobnobs each night for several weeks but no weight gain, just more visits to the bathroom. I just hope this protein mix works better as I am at a loss to why I suffer pain and find it bloody hard to put on weight now I lost it. It was unintentional weight loss caused by Constipation. I was told to eat fruit and veg something I never ate in about 15 years as I lived on mars bars (8 a day) and pizza, fish fingers and McDonalds. I can only think that my body has rebelled and now refuses to keep anything in! If this sounds like you then I sympathise and wish you the best of luck. I hope this protein works otherwise I clearly will give up trying!

    • acampbell

      Hi Tobias,
      I’m sorry that you’re getting constant abdominal pain. Have you met with a dietitian? A dietitian may be able to help you pinpoint foods that could be bothersome for you, advise you on healthier food choices, and help you with an eating plan for weight gain. Also, you might look into what is called a low FODMAP diet, which can help you determine if there are foods that you don’t tolerate well. Perhaps talk with your doctor about this. Here is a link to learn more:

    • Vanessa

      I feel exactly the same
      Same test results. Same symptoms minus the diarrhea. Eating so much crapp to gain weight my cholesterol is creeping up. I’m ready to throw in the towel! Trying an antibiotic for this left sided pain.

  • Stacy Jones

    I am a 43 year old Type 1 diabetic, diagnosed at 21 months old. Most of my teen/adult life I’ve maintained a steady weight. In the last 6 months I’ve lost about 80 lbs. without trying to, and my numerous doctors don’t have a reason why, either. The only real changes in my life over the last 6 months, have been more emotional then anything, one of my brothers passed away, I got engaged to a wonderful man, so, a little bit of good and a lot of bad. I now weigh about the same as I did in high school, at under 100 lbs. I need to reverse the weight loss, but don’t know how to do it while keeping decent blood sugar levels

    • acampbell

      Hi Stacy,

      Congratulations on your engagement! You’re right — trying to gain weight may cause your blood sugars to rise. You might start out by focusing on increasing your fat calories somewhat and seeing how that affects your blood sugars (too much fat may raise them hours later, however). But, you may find that your insulin needs will increase if you start to eat more in an effort to gain weight. My suggestion is to talk with your doctor/endocrinologist and/or a diabetes educator to come up with a game plan for how to adjust your insulin doses.