# How can hormonal disorders affect weight as they do? **URL:** \ **Category:** Factual Questions\ **Created:** [August 3, 2006, 4:12pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205 "2006-08-03T16:12:15Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 3, 2006, 4:12pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/1 "2006-08-03T16:12:15Z")
In a pit thread, people are bringing up the idea that hyperhthyroidism and other hormone problems can cause it to be very difficult to lose weight, no matter how much is eaten and how much one exercises. I don’t understand how this can be. If you eat very little, and exercise a lot, how can you still gain weight? Do these hormone problems make the body literally more efficient, so that it doesn’t burn as much when exercising? That would be ironic. But its the only theory I can come up with. Alternatively, is the claim false, or only half-true, in the first place? -FrL- ---
**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\ **Post date:** [August 3, 2006, 4:32pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/2 "2006-08-03T16:32:32Z")
One mechanism is perhaps that they can increase your appetite so you eat more. Another possiblility is that they make you feel tired, so you dont exercise as much. just a couple of WAGS mind you ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 3, 2006, 5:50pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/3 "2006-08-03T17:50:36Z")
> [@scm1001](#): > > One mechanism is perhaps that they can increase your appetite so you eat more. Another possiblility is that they make you feel tired, so you dont exercise as much. > just a couple of WAGS mind you Thanks. I was wondering, though, about the claim that a person with a hormone problem can gain weight even when he eats and exercises the same amount as a non-problemed person who is not gaining weight. -FrL- ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [August 3, 2006, 6:05pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/4 "2006-08-03T18:05:42Z")
Check out this article on [hypothyroidism](http://www.endocrineweb.com/hypo1.html) which is usually the “medical condition” referred to when people can’t lose weight as easily as others. Also see this article on [hyperthyroidism](http://www.endocrineweb.com/hyper1.html) - the opposite problem (too many hormones from thyroid, causes weight loss). This article explains the function of the thyroid nicely: > [@](#): > > In healthy people, the thyroid makes just the right amounts of two hormones, T4 and T3, which have important actions throughout the body. These hormones regulate many aspects of our metabolism, eventually affecting how many calories we burn, how warm we feel, and how much we weigh. In short, the thyroid “runs” our metabolism. So, if another person and I have the same skeletal makeup, height and gender, and I’ve got an under-active thyroid and the other person doesn’t…if we eat the same amount of cals and exercise the same amount, my body’s metabolism isn’t working at the same rate and calories aren’t being burned as efficiently as in the other person’s body. So the same amount of cals and exercise in the other person will make them sustain their weight or lose weight, but it’ll effectively do nothing for me - I might gain weight by eating the # of calories the other person eats. I’d have to ramp up my calories burned and tone down my calories consumed to be on the same track with the other person. Also note the symptoms of hypothyroidism, which **sc1001** hinted at… > [@](#): > > Fatigue > Weakness > Weight gain or increased difficulty losing weight > Coarse, dry hair > Dry, rough pale skin > Hair loss > Cold intolerance (can’t tolerate the cold like those around you) > Muscle cramps and frequent muscle aches > Constipation > Depression > Irritability > Memory loss > Abnormal menstrual cycles > Decreased libido A lot of that stuff, from weakness to fatigue to depression, let alone the amount of extra work it takes to burn calories with a slow metabolism, makes it pretty hard to overcome hypothyroidism from a physical standpoint. Me…I don’t actually have hypothyroidism. I’m just plain fat ☹ ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [August 3, 2006, 7:36pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/5 "2006-08-03T19:36:12Z")
I’d like to add (and emphasize) that hormonal problems are an infrequent cause of weight gain, and are almost never the cause of _massive_ obesity. That being said, our understanding of the relationships between the various hormones and body weight/compostion is quite limited. Indeed, although things like hypothyroidism and Cushing’s Syndrome (cortisol excess) are pretty ancient, we’ve only been aware of some of the most important weight-influencing hormones (and their associated syndromes) for a few years. In fact, for these new ones, you can almost say that they’re hormones without an associated syndrome (yet). Here are some links to articles about some of those “newer” hormones. [Link #1 (adiponectin)](http://en.wikipedia.org/wiki/Adiponectin) [Link #2 (ghrelin)](http://en.wikipedia.org/wiki/Ghrelin) [Link #3](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16622295&query_hl=1&itool=pubmed_DocSum). [Link #4](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15909762&query_hl=4&itool=pubmed_docsum). ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [August 3, 2006, 11:35pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/6 "2006-08-03T23:35:00Z")
> [@Frylock](#): > > In a pit thread, people are bringing up the idea that hyperhthyroidism and other hormone problems can cause it to be very difficult to lose weight, no matter how much is eaten and how much one exercises. > > I don’t understand how this can be. If you eat very little, and exercise a lot, how can you still gain weight? > > Do these hormone problems make the body literally more efficient, so that it doesn’t burn as much when exercising?.. > Alternatively, is the claim false, or only half-true, in the first place?.. The claim that some hormonal disorders can affect body weight is true and well understood in the medical community. In particular thyroid problems are known for this. Conceptually, thyroid hormone affects the body’s metabolism, or rate at which calories are burned. Also **hypo** thyroid patients often have less energy with which to exercise. **Hyper** thyroid patients often lose weight despite eating adequately. This is also frequently seen in domestic cats which frequently develop hyperthyroidism. The poor animals lose weight to the point of being skeletal, despite eating ravenously. This doesn’t mean that everybody with a weight problem has a hormonal disorder, simply that hormonal disorders can cause weight problems. The frequency of hormonal disorders is greater than you may think. Some studies indicate 20% of people have a pituitary tumor of some type. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [August 3, 2006, 11:40pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/7 "2006-08-03T23:40:11Z")
Although hormones can and do affect weight gain and loss in some people, it should be noted that in now way can anyone break the cardinal rule of calories in \> calories out equals weight gain, and calories out \> calories in equals weight loss. It just makes it so that if someone has a disorder, then they might actually take _in_ more calories than me while eating the same food, or they use less or more calories to do the same activity. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [August 3, 2006, 11:56pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/8 "2006-08-03T23:56:47Z")
> [@bouv](#): > > …in now way can anyone break the cardinal rule of calories in \> calories out equals weight gain, and calories out \> calories in equals weight loss. It just makes it so that if someone has a disorder, then they might actually take _in_ more calories than me while eating the same food, or they use less or more calories to do the same activity. They’re not taking in more calories while eating the same food. Caloric content is physically quantifiable and doesn’t change based on who consumes it. What changes is the rate at which those calories are burned. That is affected by activity level and metabolic rate. A hormonal disorder can cause a significantly higher or lower metabolic rate than a healthy person, independent of exercise level. That in turn can cause weight loss or weight gain. Other hormonal factors can cause weight gain or loss. For example it’s well established that anabolic steroids can cause weight gain (esp in muscle mass). Some people have higher or lower natural levels of circulating steroid hormones such as testosterone, which in turn can affect body composition and weight. The hormones progesterone and estradiol can cause weight gain depending on the amount. The gain is often as water weight but can also be as fat. Besides the amount of weight, some hormones also affect the lean/fat mass ratio. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [August 4, 2006, 12:52am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/9 "2006-08-04T00:52:35Z")
> [@joema](#): > > They’re not taking in more calories while eating the same food. Caloric content is physically quantifiable and doesn’t change based on who consumes it. Not true. For example, someone without a gall bladder won’t absorb as many calories from fat than a person with a healthy gall bladder. ---
**Author:** ![AwSnappity](https://avatars.discourse-cdn.com/v4/letter/a/a3d4f5/32.png) [@AwSnappity](https://boards.straightdope.com/u/AwSnappity)\ **Post date:** [August 4, 2006, 3:41am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/10 "2006-08-04T03:41:22Z")
My disclaimer: I have Hashimoto’s, an auto-immune form of hypothyroidism. I am not a doctor. There are several effects of hypothyroidism besides the slowed metabolism that would make it difficult for someone to lose weight and keep it off. **joema** was spot on when (s)he said that hypothyroid patients have less energy with which to exercise. Before I started treatment, I wanted to stay in bed all day long. I would have to set my alarm 15 minutes early because in the morning I was incredibly weak and it would take me that long to summon the energy to move my muscles–I was effectively paralyzed immediately after waking. I was in a constant fog, and I would often space out for 5-10 minutes without even realizing it. Even on medication (and my prescription has even been increased) I still feel extremely weak and tired; I have a hard time making it through a normal day without laying down and resting for an hour or two in the afternoon. Another possible reason hypothyroid patients are prone to gaining/retaining weight is that we’re cold all the time. I would eat in order to raise my blood sugar and try to warm up. A third reason: Depression is also a symptom, which could mean comfort eating and not wanting to exercise. FWIW, Despite all of these factors, I lost 20 lbs. in the span of 5 months by controlling what foods I ate, the portion size, and by running 3-4 miles 4-5 times a week. I wasn’t even militant about it–I didn’t count calories, I didn’t keep track of miles. I realized that I couldn’t be a victim and that I would need to constantly kick my own butt in order to slim down. (I really don’t mean for that last bit to sound like I’m so proud of myself and they should make a Lifetime Original Movie of my life.) However, I realize this anecdote doesn’t prove anything except that in one case a person with hypothyroidism was able to lose weight. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [August 4, 2006, 4:01am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/11 "2006-08-04T04:01:38Z")
> [@yoyodyne](#): > > if someone has a disorder, then they might actually take in more calories than me while eating the same food > [@yoyodyne](#): > > They’re not taking in more calories while eating the same food. Caloric content is physically quantifiable and doesn’t change based on who consumes it. What changes is the rate at which those calories are burned. > [@yoyodyne](#): > > Not true. For example, someone without a gall bladder won’t absorb as many calories from fat than a person with a healthy gall bladder. The statement was someone can take in more calories while eating the same food. That is physically impossible. Calories are a measurable unit of food energy. One calorie is the energy needed to increase the temperature of 1 g of water by 1 °C. See [Calorie - Wikipedia](http://en.wikipedia.org/wiki/Calorie) That’s like saying a Toyota Prius takes in more energy from 10 gallons of gasoline than an SUV. They both take in the same energy, but the Prius uses that more efficiently. Likewise no medical disorder causes one person to take in more calories than another while eating the same food. If their food intake is identical, so is their caloric intake. You may be thinking about health conditions that cause one person to burn energy faster or slower than another. That is different from caloric intake. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [August 4, 2006, 5:15am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/12 "2006-08-04T05:15:28Z")
> [@joema](#): > > Likewise no medical disorder causes one person to take in more calories than another while eating the same food. If their food intake is identical, so is their caloric intake. Now, unless I’ve misunderstood what you’re saying, that is patently wrong. Here are two counter-examples: If a person has a [malabsorption syndrome](http://www.webmd.com/hw/health_guide_atoz/tm6318.asp), they may eat the same food and “take in” the same number of calories as someone else, but they will, by definition, not absorb the same number of calories. They may lose weight, while a normal person gains weight, despite eating exactly the same things in the same quantity. And, from a different perspective, if someone has uncontrolled diabetes, they may eat the same food and “take in” the same number of calories as someone else, and will even asbsorb through the gut the same number of calories, but they will lose a good portion of those calories via glucose loss in the urine. Once more, they may lose weight, while a normal person gains weight, despite eating exactly the same things in the same quantity. ---
**Author:** ![Paul\_in\_Qatar](https://avatars.discourse-cdn.com/v4/letter/p/ccd318/32.png) [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)\ **Post date:** [August 4, 2006, 7:07am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/13 "2006-08-04T07:07:32Z")
In addition, some conditions, such as mine reduce the amount of body mass in muscle and increase the amount of fat. That is to say without testosterone shots I would be a pear-shaped blob. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [August 4, 2006, 11:44am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/14 "2006-08-04T11:44:23Z")
> [@joema](#): > > Likewise no medical disorder causes one person to take in more calories than another while eating the same food. If their food intake is identical, so is their caloric intake. > [@KarlGauss](#): > > Now, unless I’ve misunderstood what you’re saying, that is patently wrong… I was replying to **bouv’s** statement: _“they might actually take in more calories than me while eating the same food”_ Taking in calories (that is, caloric intake) is how many calories of food energy enters your body. It is NOT how many calories are absorbed. Look up what the phrase “caloric intake” means. It’s a common incorrect notion that one person somehow takes in more calories than another when eating the same food. Their caloric intake is identical if the food is identical. You can measure caloric value with a calorimeter: [Calorimeter - Wikipedia](http://en.wikipedia.org/wiki/Calorimeter) It’s true given identical caloric intake, two people may absorb different amounts of food energy, or may burn different amounts based on metabolism or other biological factors. However this is totally different from caloric intake, which is identical if the food intake is identical. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [August 4, 2006, 12:07pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/15 "2006-08-04T12:07:18Z")
> [@joema](#): > > I was replying to **bouv’s** statement: _“they might actually take in more calories than me while eating the same food”_ > > Taking in calories (that is, caloric intake) is how many calories of food energy enters your body. It is NOT how many calories are absorbed. Look up what the phrase “caloric intake” means. Gimme a break. You know damn well what he meant. Intake, schmintake. He meant absorbtion, which is what the OP was asking. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [August 4, 2006, 12:35pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/16 "2006-08-04T12:35:42Z")
> [@Eleusis](#): > > Gimme a break. > > You know damn well what he meant. > > Intake, schmintake. He meant absorption, which is what the OP was asking. In bouv’s post he mentioned “calories in \> calories out…”, then “take in more calories…while eating the same food”. Anybody who’s interested can do a Google search on “take in calories” and see what that means. It doesn’t mean absorbing food, but caloric intake. The term “calories in \> calories out” refers to the concept of “caloric balance”. You can Google those terms and see it’s referring to caloric energy intake, not food absorption. Now, bouv might have meant something different, and whenever he says what he means we can address that. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [August 4, 2006, 1:16pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/17 "2006-08-04T13:16:51Z")
> [@joema](#): > > Look up what the phrase “caloric intake” means. OK, boss - but for a guy who’s been around for less than a month, you’ve got quite an attitude. You may wish to rethink your ‘take’ on things. You can learn lots around here. I sure do. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [August 4, 2006, 2:37pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/18 "2006-08-04T14:37:01Z")
> [@KarlGauss](#): > > Now, unless I’ve misunderstood what you’re saying, that is patently wrong. Here are two counter-examples: > > If a person has a [malabsorption syndrome](http://www.webmd.com/hw/health_guide_atoz/tm6318.asp), they may eat the same food and “take in” the same number of calories as someone else, but they will, by definition, not absorb the same number of calories. They may lose weight, while a normal person gains weight, despite eating exactly the same things in the same quantity. > > And, from a different perspective, if someone has uncontrolled diabetes, they may eat the same food and “take in” the same number of calories as someone else, and will even absorb through the gut the same number of calories, but they will lose a good portion of those calories via glucose loss in the urine. Once more, they may lose weight, while a normal person gains weight, despite eating exactly the same things in the same quantity. Since you’re in this discussion and you’re a medical doctor and hormone specialist, one thing I’ve always wondered is how some people (doper alice in wonderland is one) with hormonal issues indicate they need only about 60% or so of the normal daily calories required to maintain a set body weight. I can easily understand not gaining weight due to caloric malabsorption per your examples, but I always thought it would take X amount of energy just to maintain the bodies basal temperature. I’ve counted calories for many years, and have determined through my own food intake and weight records, and through some research that 9-11 daily calories per lb of body weight is what is typically required simply to maintain a basal body temperature in more or less purely sedentary mode for both men and women, in the age range of 25-50 years old. Activity levels from lightly sedentary to highly active will expand that daily caloric envelope calories by approx 2-4 calories daily for a burn range of 11-15 calories per lb of body weight per day. Ultra endurance athletes can obviously be well beyond that, but we’re talking typical burn rates here. Having said all this, I was challenged in my assumptions by Alice in a previous discussion where Alice indicated that her hormonal issues allowed her to maintain a “normal” body weight on a seemingly, near impossibly low level of calories. [Here is that discussion](http://boards.straightdope.com/sdmb/showthread.php?t=379399) Astro says: > [@](#): > > I kind of wonder the same thing. I’ve counted calories (accurately) for decades and I’m pretty familiar with the range of normal metabolic requirements for adults. For 30-40 something adults of sedentary to moderate activity levels it ranges from approx 10-14 calories per lb of body weight per day. It might be more or less at the far end of the standard deviation curve if the body has some metabolic disease or related dysfunction, or if exercise levels are very high, but there are thermodynamic limits to how far that metabolic envelope can be stretched. > > Regarding PCOS I don’t see how someone is going to gain weight on an incredibly restricted calorie intake. I suppose anything is possible, but let’'s say with PCOS your body can’t process carbs correctly, and turns them (largely) to fat. So you crunch your calories down to 600 or 800 calories per day. If that’s _actually_ the amount of calories you are eating if can’t see how that’s enough energy to live re just keeping your body temperature to normal levels. You’re violating the laws of thermodynamics at that point. > > Now if you’re starting with a substantial fat reserve you could eat 600-800 calories per day for months (or possibly a year or more) without too many problems as long as you got adequate vitamins and minerals, but the PCOS sufferers claim seems to be that I will _gain_ weight at 1000 calories per day and I just don’t see (biochemically & metabolically) how that leaves you with enough energy to live Astro says: > [@](#): > > And that’s why I just can’t wrap my head around the “I only eat 800, 900 or -1000 calories per day” claims some people make. Metabolic diseases or not, you start getting much below 10 calories per lb of body weight per day, and you’re not going to be able to maintain body temperatures (asuming no substantial fat reserves) . PCOS and related diseases may screw up the way your body processes food, but it’s not going to let you live on a reptile level energy intake. It takes X amount of energy to keep the big bag of water that is the human body heated up and running. It cannot be done unless your body temperature is being substantially lowered somehow. Alice says in response: > [@](#): > > Well, I dunno. I actually use Fitday, and I measure food (which is super fun!) so I know almost exactly how many calories per day I get - 900 at the most - 700 is usual. > > Now, my normal body temperature is quite a bit below “normal” - around 96 degrees. If that’s making all the difference, great. > > But I know how much I eat, I know how much I exercise, and I know how big I am. Perhaps I defy physics - it wouldn’t be the first time I’d heard that… > > FWIW, the Dr. just increased my medication, despite getting “normal” test results, and I’m actually starting to feel like myself. That’s one thing with thyroid disorders - the range of “normal” is huge - you can get test results that fall within the appropriate guidelines, and still not be functioning normally, which is obviously very frustrating. So to my question. How is this possible? I can’t see a few degrees in body temperature making a 60% or so difference in the level of calories required. What other mechanisms are there to allow super low intake and still maintain normal functioning and activity levels? ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [August 6, 2006, 4:29am UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/19 "2006-08-06T04:29:28Z")
Sorry for the delay. Busy times . . . At the risk of sounding cliched and evasive, I think it’s the case that to a very large extent the mechansims underlying weight maintenance are still pretty much of a mystery. Some facts seem beyond debate (eg. If calories absorbed \> calories used ==\> weight gain ensues, and vice versa). But even such a simple, self-evident statement can lead to trouble if/when we don’t understand just how calories are “used” and what controls the rate of that use. For example, the act of weight loss itself, sets into motion a poorly understood phenomenon whereby it begins to take fewer calories to maintain basal metabolic rate and function than it did before the weight loss. Phrased differently, and what many dieters will tell you, is that the body becomes more “efficient” with weight loss. It gets progressively harder to lose weight. One can imagine a scenario, possibly on a genetic basis, wherein some people are more “efficient” than others even before they’ve lost weight. I use the quotation marks around ‘efficient’ for good reason. No one knows exactly what it means for your body to be more or less “efficient”. Or, more specifically, the biochemical and bioenergetic mechansims are not at all well characterized. Although not really relevant to your question, I’ll use this chance to point out a couple of the changes that occur early on in the course of weight loss: - you become more sensitive to insulin (hence fat and sugar are more easily stored) - certain enzymes in your fat tissues (eg. lipoprotein lipase) become more active (again, tending to promote fat storage) - as mentioned above, the number of calories per kilogram of body weight needed to maintain basal metabolic rate _diminishes_ (i.e. your body does the same stuff with less fuel) - your taste preference changes (eg. in blinded testing where people can only taste but not see or smell what they’re eating, weight loss leads to a preference for fattier foods. Apparently we’re hard-wired to seek out high calorie food when we’re starving) On rereading, I’m not too surprised to see that I really didn’t answer your questions. While it most certainly could be a function of my ignorance about such things, I think it’s also the case that we just don’t know very much about weight maintenance, appetite, etc. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [August 6, 2006, 1:33pm UTC](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205/20 "2006-08-06T13:33:09Z")
> [@Frylock](#): > > …people are bringing up the idea that hyperhthyroidism and other hormone problems can cause it to be very difficult to lose weight, no matter how much is eaten and how much one exercises…I don’t understand how this can be. If you eat very little, and exercise a lot, how can you still gain weight?.. > Alternatively, is the claim false, or only half-true, in the first place?.. To repeat, elements of the claim are true. A well known symptom of hyperthyroidism is weight loss, even despite ravenous eating. The prevalence and symptom are especially striking among hyperthyroid domestic cats, who often waste away, become skeletal and die, despite eating ravenously. That said, the part '_no matter how much you eat or exercise’_ is not true – if you mean that literally and not as hyperbole. Such persons if trapped in the wilderness or a concentration camp would never die from lack of food. That obviously doesn’t happen. They become thin, emaciated and eventually die. Observationally we know there’s a significant variation in body weight that accompanies certain medical conditions and treatments. Something biochemical changes to cause weight gain/loss, despite unchanging caloric intake and exercise levels. Re PCOS in human females, it’s often associated with body weight gain. The underlying biological mechanisms aren’t totally understood: _“Obesity is a prominent feature of PCOS; at least 50% of patients with PCOS are obese”_ Obesity and weight loss in polycystic ovary syndrome, Hoeger K., Obstetrics and Gynecology Clinics of North Am, 2001 March, PMID: 11293006 Another cause of weight gain (or difficulty losing weight) are commonly-used antidepressant and antipsychotic medications. Lithium, Remeron, etc. often cause this. The underlying mechanism isn’t well understood, but a recent paper said this about Remeron (Mirtazapine): _“…Weight gain is a frequent and important side effect of psychopharmacotherapy…Recent studies suggest that the fat-cell-derived hormone leptin and the tumor necrosis factor-alpha (TNF-alpha) cytokine system are pathophysiologically involved.”_ Kraus T, et al, Pharmacopsychiatry, 2002 November, PMID: 12518269. Anabolic steroids are often legally used in patients who can’t gain weight, no matter what they eat. One example are AIDS patients. The drugs obviously cause weight gain, since that’s why they’re prescribed. Here’s a key thought: _What you induce artificially with anabolic steroids, some people may already naturally have within their bodies._ E.g, there’s a wide range of normal, naturally-occurring testosterone levels within adult males, ranging from 300 ng/dl to 1000 ng/gl. It’s no great leap to hypothesize that one with a high level can gain weight (esp muscle mass) faster than one with a low level. None of this means you could feed such patients 100 calories per day and they’d still gain weight. Obviously there’s a point weight loss would still happen. However there’s ample evidence that some common hormonal factors and pharmaceutical treatments will cause weight gain, even despite moderate caloric intake control and regular exercise. [Next page](https://boards.straightdope.com/t/how-can-hormonal-disorders-affect-weight-as-they-do/367205.md?page=2)