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Does Mirena Cause Weight Gain? (What You Should Know)

Mirena is a small T-shaped intrauterine device (IUD) that releases the progestin hormone “levonorgestrel” to prevent: pregnancy, heavy menstrual periods, and/or excessive build of the uterus lining in persons on estrogen replacement therapy.  When properly inserted within the uterus, Mirena is programmed to release 20 micrograms of levonorgestrel per day, and is expected to remain effective for a duration of 3 to 5 years.

According to medical literature, intrauterine devices like Mirena remain among the most effective formats of birth control on the market, exhibiting one-year failure rates of approximately 0.2%.  Furthermore, the World Health Organization lists levonorgestrel-containing IUDs as “Essential Medicines,” or drugs that are safe, highly effective, and necessary in a basic health system.

It is understood that many women prefer using hormonal IUDs like Mirena over other contraceptives (e.g. birth control pills) because they are low-maintenance, “set-it-and-forget-it” options – requiring no daily, weekly, or monthly adjustment.  Despite the fact that Mirena is an effective contraceptive, prospective users may be concerned about whether Mirena might cause weight gain as a side effect.

Mirena & Weight Gain (Potential Causes)

Data from large-scale randomized controlled trials of Mirena indicate that weight gain can occur as an adverse reaction in a small percentage of users – particularly when implanted for a long-term.  In a majority of Mirena users, weight gain that occurs during treatment is likely to be: (1) clinically insignificant (less than 7% body weight increase) and/or (2) not directly attributable to Mirena.

Clinically significant weight gain (over 7% body weight increase) is an infrequent adverse reaction that’s estimated to occur in less than 2% of users.  Nevertheless, just because medical literature suggests that weight gain is unlikely to be caused by Mirena, this does not mean that Mirena never causes unwanted weight gain.

There is a minuscule chance that you could be in the minority (2%) of individuals who are prone to experiencing significant weight gain as a reaction to Mirena.  In the event that you gain a substantial amount of weight after Mirena insertion, below are some hypothetical explanations as to why the weight gain might’ve occurred.  That said, you should realize that the underlying cause(s) of weight gain among users may be subject to interindividual variation.

Appetite increase: Among persons who experience weight gain after Mirena implantation, one potential cause is increased appetite.  Many anecdotal reports online claim that appetite substantially increased from Mirena, and that this appetite increase caused weight gain.  It is unclear exactly how Mirena might increase appetite, however, some speculate that systemic levonorgestrel exposure might be culpable.

Specifically, levonorgestrel might modulate gut bacteria concentrations and/or activity within certain brain regions to stimulate appetite.  In the event that your appetite increases (even a little bit) after a Mirena implant, this might make it difficult to control yourself around food – leading you to consume a greater number of calories than you did before the implant.  Consuming a greater number of calories following Mirena insertion (compared to pre-insertion) will likely yield weight gain.

Bloating: Another potential cause of weight gain among Mirena users is bloating, or an accumulation of fluid and/or gas within the body.  Bloating is considered a common side effect of Mirena, and one that could account for a modest increase in body weight.  That said, weight gain attributable to bloating is usually not a major concern due to the fact that the weight increase is related to water and/or gas retention – not actual fat gain.

Assuming you become bloated from Mirena and gain a few pounds as a result, understand that this bloating-related weight gain should be relatively easy to lose following Mirena removal.  Moreover, it may be possible to decrease bloating (and associated weight gain) with simple dietary modifications (e.g. reducing sodium intake), exercising regularly, and by drinking more water.  Anecdotal accounts suggest that bloating may be more severe with long-term Mirena use (e.g. several years) – compared to short-term use.

Cognitive function: Another way in which Mirena could indirectly affect body weight is by altering cognitive function and/or thought patterns.  Research shows that levonorgestrel (combined with ethinyl estradiol) decreases concentrations of BDNF in the hippocampus, which likely reduces the growth of new brain cells and neuroplasticity.  Additionally, levonorgestrel (20 mcg) with ethinyl estradiol (10 mcg) reduces noradrenergic signaling in the hippocampus – which could impair learning and memory.

Though the effect of standalone levonorgestrel (20 mcg) on cognition isn’t fully elucidated, it’s reasonable to hypothesize that it could interfere with aspects of cognitive function.  Interference with aspects of cognitive function such as self-regulation, planning, learning, and/or memory – might reduce self-control around food and/or one’s ability to plan healthy (low calorie) meals.  If you notice altered thoughts and/or cognition while using Mirena, it’s possible that this could indirectly lead to weight gain.

Fat gain: A systematic review by Lopez et al. (2016) referenced 2 studies in which hormonal intrauterine contraception caused body fat gain.  The studies suggested that users of hormonal intrauterine contraception (e.g. Mirena) were at risk of experiencing fat gain and muscle loss.  Though it remains unclear as to why a hormonal intrauterine contraception like Mirena would cause fat gain, it’s possible that systemic levonorgestrel exposure reduces fat metabolism and/or increases fat storage.

If your body is burning less fat and/or storing more fat after Mirena implantation than before using Mirena, this may be the reason as to why you’re gaining weight.  Modifying the macronutrient composition of your diet and/or monitoring your calorie intake could help counteract the fat gain (and muscle loss) that may occur from Mirena.  Moreover, engaging in regular physical exercise (cardio and weight lifting) could help prevent or minimize the significance of unwanted body composition changes.

Food cravings: Following the insertion of Mirena, some women claim to develop food cravings.  The cravings may be for specific macronutrients such as fats or carbohydrates, but might also be for hyperpalatable (high fat, high sugar, high salt), calorically-dense foods such as: cakes, ice cream, donuts, candies, etc.  If the food cravings are constant and/or overwhelming, and you’re unable to resist them – it’s reasonable to expect that you’ll overeat and gain some weight.

Furthermore, a major problem with food cravings is that, once you “cave in” and allow yourself to consume hyperpalatable, calorically-dense foods – this activates reward centers in the brain, reinforces the behavior, and increases likelihood of future food cravings.  If you know that Mirena causing your food cravings, and you cannot resist these cravings (such that you’re overeating and gaining weight), you may want to switch to another contraceptive.

Gastrointestinal changes: It’s possible that systemic exposure to levonorgestrel (the synthetic hormone released by Mirena) could affect the gastrointestinal tract.  Some speculate that levonorgestrel might alter microbial composition within gut flora, and in turn, this alteration could stimulate appetite and lead to weight gain.  For example, if levonorgestrel increases concentrations of pathogenic bacteria in the gut, users might exhibit: altered insulin signaling; increased inflammation; increased appetite; and/or increased fat storage – each of which could lead to weight gain.

Even if Mirena doesn’t significantly alter the gut microbiome, it could cause constipation (as a side effect), which might account for modest weight gain.  If you become constipated after Mirena insertion, this means your body is having difficulty excreting digested food.  The accumulation of digested food could lead to bloating and unwanted weight gain.  Fortunately, dietary modifications, exercise, and adequate hydration can usually help treat constipation – and could help prevent constipation-related bloating and weight gain.

Low energy: Some women have reported experiencing low energy or fatigue as a side effect of Mirena.  If the levonorgestrel being released by Mirena is causing fatigue or lethargy, this may interfere with your motivation to exercise and/or stay physically active.  Assuming you stop exercising, exercise less than usual, or exercise with lower intensity while using Mirena – you may burn fewer calories (than before its insertion) such that you end up gaining weight.

In certain users, the fatigue or low energy may be directly related to Mirena-induced mood swings or depression.  Others might experience low energy as a result of the anti-androgenic effect of levonorgestrel.  If you become fatigued while taking Mirena and your physical activity level decreases as a result, then: you’ll burn fewer calories, your resting metabolic rate will slow (relative to your weight), and you’ll gain weight.

Mood swings: Medical reports suggest that levonorgestrel-containing contraceptives like Mirena can cause mood swings in a subset of users.  These mood swings may be accompanied by increased anxiety and/or depression – each of which could affect appetite, food choices, physical activity, and metabolic rate.  It is known that high anxiety and/or severe depression may cause certain individuals to consume hyperpalatable, high-calorie foods as a coping mechanism.

Assuming Mirena-induced mood swings lead you to consume a greater number of calories than usual – this could explain your weight gain.  Furthermore, negative moods like depression may reduce your energy level, motivation to exercise, and resting metabolic rate.  If you become sedentary or cut back on exercise due to Mirena-induced depression, there’s a good chance that you’ll end up gaining weight.

Hormone changes: Mirena may cause weight gain by altering the hormone profile within your body.  It is known that after insertion, Mirena releases 20 mcg of levonorgestrel per day within the body.  Systemic exposure to levonorgestrel may decrease the body’s production of endogenous progesterone, and this reduction in progesterone secretion might lead to estrogen dominance – ultimately causing weight gain.

Additionally, it has been shown that levonorgestrel can exert an antiandrogen effect whereby it increases concentrations of sex-hormone binding globulin (SHBG).  Increases in sex-hormone binding globulin reduce concentrations of free testosterone.  Lower concentrations of serum testosterone coupled with estrogen dominance could yield: increased fat gain; muscle loss; and slowed metabolism – all of which may account for weight gain and/or unfavorable changes in body composition.

Slower metabolism:  It’s possible that the levonorgestrel that’s secreted by Mirena could slow your resting metabolic rate to cause weight gain.  If Mirena causes fatigue, depression, decreases non-exercise related thermogenesis, or leads you to exercise less than usual – your body may burn fewer calories than it normally does while at rest.

Decreases in progesterone and free testosterone, coupled with changes in body composition (e.g. muscle loss) [as a result of levonorgestrel exposure] might further slow your resting metabolic rate.  If your resting metabolic rate slows significantly after Mirena insertion, then you may gain weight even if you’re consuming roughly the same number of calories that you did before using Mirena.

Note: There may be additional explanations for a person’s weight gain on Mirena (besides those mentioned above).  If you can think of any science-supported reasons as to why Mirena might cause weight gain, share these reasons in the comments.  Moreover, it is important to understand that many of the hypothetical weight gain causes could occur regardless of Mirena use.

Mirena & Weight Change (The Studies)

There are many studies that have been conducted to determine the effect of Mirena (and related contraceptives) on body weight.  Most evidence from large-scale randomized clinical trials indicates that the Mirena IUD is unlikely to cause significant weight change as a side effect.  Although there’s evidence indicating that Mirena might cause modest weight gain (in a small percentage of users), most medical doctors consider Mirena to be “weight neutral.”

2016: Effects of progestin-only birth control on weight.

Researchers Lopez, Edelman, Chen, et al. investigated the association between progestin-only contraceptive use and body weight change – and published their findings in the Cochrane Database of Systematic Reviews.  For the review, the researchers gathered results from studies that were published up until August 2016 in: MEDLINE, CENTRAL, POPLINE, LILACS, ClinicalTrials.gov, and ICTRP.

To be included in the review, studies needed to: (1) assess the effect of a progestin-only contraceptive in comparison to another contraceptive or no contraceptive; and (2) document mean change in body weight or body composition of contraceptive recipients.  A total of 22 studies (5 RCTs and 17 NRS) encompassing 11,450 women met inclusion criteria set by researchers.

Of these 22 studies, 4 involved levonorgestrel-releasing intrauterine contraception (LNG-IUC).  Several studies documented increases in body fat mass (%) and decreases in lean mass (%) among women using progestin-only contraceptives, suggesting that contraceptives like Mirena may alter body composition by promoting fat gain and reducing muscle mass.

However, researchers considered the total quality of evidence from studies to be low – as over half of the studies generated “low quality” results.  Nevertheless, researchers concluded that there’s limited evidence indicating that use of progestin-only contraceptives may cause weight gain of up to 4.4 lbs. (2 kg) when administered for 6 to 12 months.

What’s more, longer-term data indicate that average weight change was nearly 2-fold after the use of a progestin-only contraceptive for 2 to 4 years – compared to use for just 1 year.  Still, although the weight gain nearly doubled from 2 to 4 years of progestin-only contraceptive use, it was not statistically greater in comparison to just 1 year of use.

Researchers recommended that informing patients of average weight gain associated with progestin-only contraceptives may improve treatment compliance and decrease discontinuation (stemming from fear of weight gain).  Overall, this review suggests that while a small amount of weight gain might occur with long-term progestin-only contraceptive use, it’s unlikely to significantly exceed 4.4 lbs.

2014: Levonorgestrel-releasing intrauterine system (Mirena) in compare to medroxyprogesterone acetate as a therapy for endometrial hyperplasia.

Behnamfar, Ghahiri, and Tavakoli organized a randomized controlled trial to determine the efficacy of Mirena (levonorgestrel-releasing IUD) compared to oral medroxyprogesterone acetate for the treatment of endometrial hyperplasia.  Researchers recruited 60 women who had been diagnosed with endometrial hyperplasia and randomly assigned them to one of two groups: Mirena or medroxyprogesterone (10 mg/day; 12 days per month) – for a 3-month duration.

In addition to comparing the effectiveness of Mirena and medroxyprogesterone, researchers compared side effects, including weight change.  Results indicated that weight gain occurred in 6 Mirena recipients (21.4%) and just 1 medroxyprogesterone recipient (3.7%).  Although this was a relatively small-scale and short-term study, it supports the idea that Mirena can cause weight gain in a subset of users when used for 3 months.

2011: A randomized clinical trial to compare levonorgestrel-releasing intrauterine system (Mirena) vs trans-cervical endometrial resection for treatment of menorrhagia.

Ghazizadeh, Bakhtiari, Rahmanpour, et al. conducted a randomized controlled trial in which the effectiveness of Mirena was compared to that of trans-cervical endometrial resection – for the management of menorrhagia (heavy bleeding at menstruation).  A total of 104 women diagnosed with menorrhagia were recruited for participation and randomly assigned to receive: Mirena or trans-cervical endometrial resection.

After the treatments, trial participants were instructed to maintain a menstrual record of: menstrual cycles, days of bleeding, number of stained towels in one day, amount of staining, and adverse effects –including weight gain.  Results of the trial indicated that both interventions were successful and well-tolerated by recipients for the treatment of menorrhagia.

Among the 52 recipients of Mirena, just one patient had to remove the device due to unacceptable spotting and weight gain.  Because only one Mirena recipient experienced significant weight gain within 12 months after insertion, weight gain was considered an uncommon side effect.

2009: The levonorgestrel-releasing intrauterine system: Safety, efficacy, and patient acceptability.

Beatty and Blumenthal published an article reporting upon the effectiveness, safety, and patient satisfaction with Mirena (levonorgestrel-releasing intrauterine system).  In the article, it was noted that levonorgestrel-releasing IUDs are utilized by upwards of 150 million women worldwide for the prevention of: pregnancy, menorrhagia, endometriosis, and endometrial hyperplasia.

According to data gathered by researchers, Mirena and other devices are well-tolerated with high rates of patient satisfaction.  However, even though the device is safe, effective, and well-tolerated – it can occasionally cause unwanted side effects like: ovarian cysts, acne, depression, sexual dysfunction, and weight gain.  (Authors did not document the specific likelihood of weight gain in this report).

2008: Review of the safety, efficacy and patient acceptability of the levonorgestrel-releasing intrauterine system.

Kailasam and Cahill reported that levonorgestrel-containing IUDs are an effective, reversible, and safe form of birth control.  In their article, researchers stated that, in addition to preventing pregnancy, levonorgestrel-containing IUDs may prove useful in treating medical conditions like: menorrhagia, symptomatic fibroids, and endometriosis.

It was further mentioned that adverse effects associated with levonorgestrel-containing IUDs are generally categorized as: “device-related” (related to the presence of the device) and “levonorgestrel-related” (related to the physiologic actions of levonorgestrel).  Though adverse effects are uncommon, researchers listed weight gain as a potential reaction – attributable to systemic levonorgestrel exposure.

2006: Weight variation in users of the levonorgestrel-releasing intrauterine system, of the copper IUD and of medroxyprogesterone acetate in Brazil.

Yela, Monteiro, Bahamondes, et al. conducted a study in Brazil to assess the long-term effect of levonorgestrel IUDs, copper IUDs, and medroxyprogesterone acetate (DMPA) – on body weight.  For the study, 163 women using levonorgestrel IUDs were matched by weight and age to women using copper IUDs and women using DMPA – and monitored over a 5-year period.

The body weight and BMI (body mass index) of each participant was measured and recorded after each year of the study.  At the onset of study, average body weights and BMIs among the groups were: 62.9 kg and 25 (levonorgestrel IUD); 62.8 kg and 26.4 (copper IUD); and 62.5 kg and 25.5 (DMPA).

After the 5-year study, average body weight and BMI increases among the groups were: 3.1 kg (6.83 lbs.) and 1.3 (levonorgestrel IUD), 4.9 kg (10.8 lbs.) and 2.1 (copper IUD), and 8.2 kg (18 lbs.) and 3.2 (DMPA).  An analysis by the researchers indicated that there was an association between duration of contraceptive use and weight gain.

It was concluded that 5-year use of levonorgestrel IUD (i.e. Mirena) and copper IUD do not cause clinically relevant weight gain – whereas DMPA causes weight gain.  That said, the average weight gain associated with the use of Mirena over a 5-year span was ~6.83 lbs – indicating that the device could cause [clinically insignificant] weight gain.

According to research: Does Mirena cause weight gain?

Yes – Mirena may cause modest weight gain.  Medical literature indicates that Mirena (levonorgestrel-containing IUD) can cause weight gain in a small percentage of users, particularly when implanted for a long-term.  Researchers speculate that weight gain may occur as a result of [low concentrations of] levonorgestrel circulating throughout the body.

However, despite the fact that weight gain might occur in a subset of Mirena users, a majority of users will not exhibit clinically relevant weight gain (characterized as a 7% increase in body weight from baseline).  The National Collaborating Centre for Women’s and Children’s Health (UK) published a set of NICE Clinical Guidelines (2005) for levonorgestrel-containing IUDs (like Mirena) stating that weight changes in women of reproductive age is common regardless of hormonal contraceptive use.

Authors of the NICE publication referenced a randomized controlled trial with (1821 levonorgestrel-IUD recipients) suggesting that removal of the IUD due to weight gain occurred in just 1.5% of users.  The NICE publication referenced second randomized controlled trial (with 2246 participants) in which weight gain occurred in 0.7% of Mirena users and third non-comparative study (with 678 participants) in which Mirena was removed by 16 women (2.35%) due to weight gain – over a 5-year term.

The NICE publication concluded that while rates of weight gain were higher in studies among levonorgestrel-containing IUDs (e.g. Mirena) than other IUDs, there remains insufficient evidence to conclude that levonorgestrel-containing IUDs cause more weight gain than other IUDs.  Finally, NICE Clinical Guidelines recommended informing women that “there is no evidence that IUS use causes weight gain.”

A study by Yela et al. (2006) with 163 Mirena users reported an average weight gain of 6.83 lbs. over the span of 5 years, yet this amount of weight gain was considered “clinically insignificant.”  Moreover, in the aforementioned study, the amount of weight gain observed in Mirena users was similar to other copper IUD users – and significantly less than DMPA users.

Additionally, a study by Ghazizadeh et al. (2011) reported that just 1 of 52 Mirena users (2%) experienced significant weight gain within 12 months after its insertion, supporting the idea that weight gain is an uncommon reaction.  Then again, a study by Behnamfar et al. (2014) documented significant weight gain as occurring in 6 of 28 Mirena users (21.4%) within 3 months of insertion.

Perhaps the highest quality evidence for determining whether Mirena causes weight gain can be derived from a Cochrane Review by Lopez et al. (2016).  Data from this review suggested that Mirena might cause a body weight increase of up to 4.4 lbs. (2.2 kg) in a small percentage of users when administered for up to 12 months – possibly via the promotion of fat gain.

In summary, there’s some data to suggest that Mirena may cause modest weight gain (up to 4.4 lbs.) in a subset of users when administered for a long-term.  That said, the amount of weight gain that most Mirena users are likely to experience should not be considered clinically significant.

Variables that influence Mirena-related weight gain

There are numerous variables that could influence likelihood of weight gain following Mirena insertion.  Variables that might influence odds of weight gain among Mirena users include: baseline body weight; duration of Mirena use; concurrent substance use; prior substance use; lifestyle; and genetics.  It is the combination of these variables that probably explain why some Mirena users are prone to significant weight gain, whereas others aren’t.

  1. Baseline body size & weight

The baseline body size and weight of a Mirena user may influence the odds of gaining weight after insertion.  Among women who are prone to levonorgestrel-induced weight gain, it is hypothesized that having a smaller body size and lower baseline body weight could increase odds of weight gain during treatment.

This is because, women with smaller body sizes and/or lower weights are essentially receiving a greater dose of levonorgestrel per day relative to size and weight – than women with larger body sizes and heavier weights.  Because Mirena is manufactured to release 20 mcg levonorgestrel per day, regardless of the user’s body size and/or weight, lighter and/or smaller users may endure greater relative systemic exposure to levonorgestrel.

Greater systemic exposure to levonorgestrel [relative to body size] might induce more substantial physiologic changes – than lesser systemic exposure [relative to body size].  For this reason, it’s fair to speculate that smaller-sized women with low body weights may be prone to greater weight gain while using Mirena – than larger-sized and/or heavier users.

  1. Duration of Mirena use

The total duration over which Mirena is used may determine whether weight gain occurs, and if it does, the specific amount that a user gains.  According to medical research, long-term Mirena users are at increased risk of exhibiting clinically significant weight gain – compared to short-term users.  A systematic review noted that the usage of Mirena for 2 to 4 years induced double the amount of weight gain than the usage of Mirena for 1 year.

Increased risk of weight gain among long-term Mirena users could be due to cumulative physiologic changes accrued [over an extended duration] from daily levonorgestrel exposure.   Moreover, perhaps things like: food cravings, lower energy, muscle loss, fat gain, and slower metabolism – are synergistic, such that over a long-term, they contribute to more significant weight gain than they could over a shorter-term.

Although research indicates that long-term Mirena use increases risk of weight gain – and the amount of weight gain (among those who experience a gain), not all Mirena users will necessarily gain more weight over the long-term than the short-term.  It’s possible that weight gain might occur over the short-term (due to the body adjusting to levonorgestrel) followed by no additional weight change (once the body has adapted to the regular presence of levonorgestrel).

  1. Concurrent substance use

If you’re using other substances along with Mirena, including: prescription drugs; over-the-counter medications; illicit drugs; and/or supplements – there’s a chance that these substances could influence your odds of gaining weight after Mirena insertion.  Concurrently used substances might: interfere with Mirena’s effect (preventing Mirena-related weight gain); counteract the physiologic mechanisms of Mirena-induced weight gain; augment the physiologic mechanisms of Mirena-induced weight gain; or cause weight gain (irrespective of Mirena).

It’s possible that certain concurrently-administered substances could decrease the intrauterine efficacy of levonorgestrel (released by Mirena).  If you’re using a substance that interferes with the effect of levonorgestrel, Mirena may not work as intended for medical purposes – but weight gain will be less likely to occur (because systemic levonorgestrel exposure will have been reduced).

Another possibility is that concurrently-administered substances might end up counteracting Mirena-induced weight gain.  For example, if you received a Mirena insertion, and you also started using a psychostimulant medication to treat ADHD – the anorectic effect of the psychostimulant will probably counteract and prevent any weight gain effect of Mirena.  In fact, in this hypothetical scenario, you may even end up losing weight while using Mirena due to the strong anorectic effect of the psychostimulant.

On the other hand, concurrently-administered substances might augment Mirena-induced weight gain – causing you to gain significantly more weight than had you used Mirena as a standalone.  For example, if you received a Mirena insertion, and you also initiated treatment with an antipsychotic medication to treat schizophrenia – the physiologic actions of the antipsychotic medication may promote weight gain and add to any weight gain attributable to Mirena.

That said, anyone using substances with Mirena should be cognizant of the fact that weight gain could be fully attributable to concurrently-administered substances – rather than the Mirena.  In other words, some individuals might mistakenly assume that their weight gain was caused by Mirena, when it was really caused by other substances that are regularly administered.

  1. Prior contraceptive / substance use

Any substances that you used prior to Mirena could impact the amount of weight gain that you experience following Mirena insertion.  For example, if you administered a contraceptive (or another medication) before Mirena that caused you to lose weight, it’s very likely that you’ll end up gaining weight following its discontinuation.

If you begin using Mirena shortly after discontinuation of a contraceptive (or another medication) that induced weight loss, you’ll probably notice weight gain while on Mirena.  However, in this case, the weight gain that you notice may be completely attributable to the fact that you’re no longer receiving the weight loss effect of the formerly-administered contraceptive – rather than caused by Mirena.

Oppositely, if you administered a contraceptive (or another medication) before Mirena that caused you to gain weight, you might notice weight loss (or no change in weight) after Mirena insertion.  In this case, the weight loss (or lack of weight change) may be fully attributable to the fact that you’re no longer receiving the weight gain effect of the formerly-administered substance – rather than caused by Mirena.

Realize that if you gain or lose weight while using Mirena – the weight change that you experience could be due to the recent discontinuation of another substance (that had affected your weight) – rather than from introduction of Mirena.  For this reason, if you recently discontinued another contraceptive or medication before starting Mirena – consider that this may account for your weight gain.

  1. Lifestyle & genetics

Lifestyle and gene expression of Mirena users might determine whether weight gain occurs during treatment.  It is reasonable to suspect that persons who make an effort to live healthy may be protected against weight gain while using Mirena – in comparison to persons who make zero effort to live healthy.  Specifically, doing things like: consuming a nutrient-dense diet, keeping stress low, exercising regularly, and tracking calories (to avoid being in a caloric surplus) – may help prevent significant weight gain while using Mirena.

Conversely, persons who: eat high calorie foods, never track calories, never exercise, and have high stress – may be at increased risk of weight gain while using Mirena.  Among individuals who make unhealthy lifestyle choices – weight gain might occur on Mirena irrespective of the IUD’s effect.  In other words, someone who lives unhealthily may end up gaining weight simply due to bad habits, rather than from Mirena (even though the user might blame her weight gain on Mirena).

In addition to lifestyle, there may be genes that increase (or decrease) risk of weight gain on Mirena.  Though specific genes haven’t been identified as possible influencers of Mirena-induced weight gain, it is known that expressing certain genes can increase odds of weight gain in general – and while using other pharmaceutical medications.  For this reason, it’s fair to speculate that gene expression (in conjunction with lifestyle) could determine whether weight gain occurs on Mirena.

Could Mirena ever cause weight loss?

Possibly.  Though no research suggests that Mirena (or levonorgestrel-containing IUDs) cause weight loss, anecdotal accounts have documented weight loss as a reaction.  If weight loss occurs on Mirena, it may be more attributable to the lifestyle of the user – rather than the effect of levonorgestrel.  Nevertheless, hypothetical explanations as to why weight loss could occur from Mirena are listed below.

  • Appetite loss: While many individuals report an appetite increase on Mirena, others will notice appetite decrease – or loss of appetite. The loss of appetite may be related to other fairly common side effects such as: mood changes (e.g. depression), nausea, and/or vomiting.  Assuming your appetite plummets on Mirena, regardless of the reason, this could cause you to consume fewer calories than usual such that you lose weight.
  • Cognitive deficits: An unlikely [although possible] reason as to why Mirena may cause weight loss is via induction of cognitive deficits. Some studies show that Mirena may impair aspects of cognition like memory and learning.  If cognitive deficits become severe, they might cause someone to “forget to eat” certain meals and/or adequate calories to maintain their current weight.
  • Diarrhea: A side effect of Mirena that could be culpable for a user’s weight loss is diarrhea. Diarrhea is a condition in which frequent bowel movements and loose stools occur due to the rapid movement of food through the digestive tract.  If you experience diarrhea while using Mirena, diarrhea could dehydrate the body and interfere with calorie absorption – likely leading to weight loss.
  • Mood changes: Contraceptives like Mirena can sometimes trigger mood changes and neuropsychiatric symptoms like anxiety and depression. For some individuals, anxiety and depression can reduce appetite and food intake and increase restlessness (and non-exercise activity thermogenesis).  If Mirena-induced mood changes cause you to eat less and/or fidget more than usual, this could result in weight loss.
  • Nausea & vomiting: Nausea and vomiting have been reported as possible adverse reactions to Mirena. Severe nausea and/or vomiting might interfere with your appetite and cause you to consume fewer calories than usual – thus accounting for your weight loss.  Additionally, vomiting can induce weight loss by impairing food absorption and dehydrating the body.
  • Taste perversion: An extremely rare adverse reaction to Mirena that might occur is taste perversion. Taste perversion may be described as: loss of taste, decreased taste sensitivity, and/or changes in taste.  If you find that foods don’t taste quite as good as they did before using Mirena, taste perversion might lead you to eat fewer calories whereby you lose weight.

Possible strategies to reduce weight gain with Mirena

According to long-term studies, most Mirena users probably won’t experience “clinically significant” weight gain.  However, if you’re still concerned about potential weight gain from Mirena, listed below are some weight management strategies that you may want to utilize.  Prior to employing any of the weight management strategies documented below – consult a medical doctor to verify that they’re safe based on your current medical status.

  1. Calorie tracking: Most individuals who claim to have gained weight while using contraceptives like Mirena are not tracking calories. Because calories aren’t being tracked – it’s impossible to know whether the weight gain was really caused by the drug or random fluctuations in food consumption (that would’ve occurred regardless of Mirena use).  To prevent weight gain while using Mirena, it is recommended to determine your body’s maintenance calories (i.e. calories needed to maintain your current weight) – and consume this number during treatment to prevent major weight gain.  If you’re noticing some weight gain, you can simply reduce your daily caloric intake slightly until the weight gain stops.
  2. Regular exercise: Regularly exercising while using Mirena is recommended if you’re trying to prevent weight gain. Engaging in aerobic exercise and resistance training should help prevent: slowing of metabolic rate, increased fat storage, and muscle loss – while using Mirena.  If you perform exercise and track your calories – you’ll further decrease your odds of gaining weight.
  3. Manage side effects: As was mentioned, certain side effects of Mirena may directly cause, or indirectly lead to, weight gain. For example, if you notice bloating, constipation, and/or a spike in appetite after Mirena insertion – these could promote weight gain.  By identifying these side effects and managing them (based on recommendations from a medical doctor) – you may be able to prevent weight gain from occurring.  For example, if some of your weight gain is caused by constipation – then treating the constipation might help normalize your body weight.
  4. Eliminate substances: If you’re gaining weight while using Mirena, the weight gain could be caused [in part] by concurrently administered substances. For this reason, you may want to evaluate all substances that you’re using along with Mirena (medications, supplements, etc.) and discontinue all agents that aren’t deemed “medically necessary.”  Discontinuation of medically-unnecessary substances may result in weight normalization due to the fact that your weight gain was caused more by these agents than the Mirena.
  5. Add-on substances: If Mirena is causing weight gain, and you [for whatever reason] are unable to restrict calories and/or increase exercise – you may want to ask a medical doctor about adding a medication to your regimen that would help with weight loss. Certain medications might reduce appetite, speed up metabolism, and/or increase energy (and motivation to exercise) – all of which could make it easier to avoid weight gain while using Mirena.
  6. Use Mirena for a longer-term: Even though research suggests that weight gain is more common among long-term Mirena users than short-term users, the weight gain that emerges over a long-term isn’t considered “clinically significant.” Furthermore, if you’ve only been using Mirena for a few days or weeks and are noticing weight gain, it’s possible that the weight gain might be transient – such that weight may normalize with longer-term use (as the body becomes better adapted to Mirena).  It’s also possible that modest weight gain may occur over a short-term followed by weight maintenance (or no additional increase over a longer-term).

Note: If none of the strategies documented above help to prevent or reduce weight gain on Mirena, you may need to reflect upon whether the therapeutic benefit of Mirena “outweighs” the weight gain side effect.  If the weight gain is significant and/or overwhelming – you should inform your doctor and consider alternative contraceptive options.

Have you gained weight while using Mirena?

If you’ve used Mirena IUD for a moderate duration, leave a comment discussing whether you’ve noticed weight change (weight gain or loss) after its insertion.  If you’ve noticed weight change after Mirena insertion, how much weight did you gain or lose?  Do you believe that the weight change is directly attributable to Mirena?

Assuming you think that the weight change is attributable to Mirena, how do you think Mirena caused the weight change?  (Possible answers might include things like: appetite increase; bloating; constipation; fat gain; food cravings; slowing of metabolism; etc.).

To help others understand your situation, provide additional details in your comment like: how long you’ve had Mirena inserted; whether you use other substances (medications, supplements, etc.); your preexisting medical conditions; and whether you track calories plus exercise regularly.  If you use other substances with Mirena, have a preexisting medical condition, and/or don’t track your calories or exercise consistently – how can you be sure that your weight change is from Mirena?

In conclusion, while modest weight gain (of up to 4.4 lbs.) might occur in a small percentage of women using Mirena (particularly over a long-term), moderate and/or severe weight gain is unlikely.  Moreover, most medical doctors consider Mirena to be a “weight neutral” medication and The National Collaborating Centre for Women’s and Children’s Health (UK) recommends telling patients that there’s no evidence that IUDs [like Mirena] cause weight gain.

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