This Is Why You Started Gaining Weight Out of Nowhere

There's no discovery quite as startling as stepping on the scale and weighing way more than you thought you did (or trying on your favorite pair of pants only to realize that they fit a little tighter than they did the week before) with absolutely no idea why.

Most of the time we can pinpoint our weight gain from, say, an overly indulgent vacation in which we downed a dessert with every meal or a newfound affinity to eat out on the regular. But, then there are those times when we experience unexplained weight gain-the kind of weight gain that seems to show up overnight, out of nowhere, and seemingly for no reason.

When you can't find a culprit for why you are gaining weight, it might be one of these seven sneaky reasons.

Lack of Sleep

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Not getting enoughВ sleep has been repeatedly scientifically linked toВ a significantВ increase in weight.В In one instance, a study published in the journal Sleep found that women who slept less than six hours a night were more prone to weight gain, by a factor of 11 pounds, than women who slept at least seven hours each night. This is likely due to the effect that insufficient sleep has on the endocannabinoid system, also known as theВ hormones that regulate appetite; lack of sleep stimulates the ones that tell you you're hungry. It may also be partially due to the fact that when you're tired, you're less likely to exercise or move as much throughout the day. So be sure you're clocking enough shut-eye, as your late nights might be adversely affecting your waistline.В

Your Medication

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When you gain weight, the first place you look for answers is often your diet or exercise routine, but the culprit canВ be hiding in your medicine cabinet. Many medications, includingВ ones that treat migraines and mood disorders, as well as birth controlВ and steroids, can cause weight gain for a variety of reasons. If you suspect a medication you're taking might be causing weight gain, talk to your doctor to discuss your options.В


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Like with insufficientВ sleep, stress can cause weight gain because of hormones.В When the body experiences stress, itВ causes a surge in the hormone cortisol, whichВ leadsВ to an increased appetite (to fuel your fight-or-flight response). On top of that, stress is often the reason you can't fall asleep at night, or what wakes you up and keeps you up in the middle of the night-aka, a doubleВ whammy to your midsection. Exercising regularly is well-loved solution, as working out not only lowers stress, it also (obviously) helps with weight loss.В

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Your Job

If you've had a nine-to-five desk job for a while, you might not suspect it as a reason for weight gain, but the effectsВ of officeВ life on weight go beyond the sedentary nature of it,В and can compound quickly. Maybe a new project hasВ youВ working late nights (and thus you're not getting enough sleep (see slide one) and super stressed (see previous slide), and/or you're too busy to throw together a healthy lunch, so you're eating more fattening fast food than you realize. Throw in someВ mindless snacking on the communal food in the kitchen, and a co-worker's birthday donuts for the team, and the pounds might just start to add up in more ways than one.В


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Sometimes the reason behind the scale reading a number other than what you expect is actually your sodium intake. When sodium is the culprit, you haven't actually gained body fat;В your body is just retaining water weight to dilute the sodium. Outside of salt alone, unlikely sources of sodium include plenty of salad dressings and sauces, frozen meals, and bread. If you focus on cutting back on sodium, this form of weight will disappear pretty quickly.В

Water Retention

Again, like with sodium,В water weight isn't fat, but it can tip the scale and make you feel heavier. Though it might sound counterintuitive, the solution to clearing that water weightВ is actually… to drink more water. TheВ reason your body seems to be holding on to the water weightВ is because you're not drinking enough fluids, so it thinks it has to store the water it doesn'tВ have in reserve.В

Weight Training

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Confusingly, you might find that you've gained weight after you start working out more, which happens for two reasons. First, weight training increases muscle mass, and muscle is more dense than fat, so as you lose fat and increase muscle, you might see a higher number on the scale. Second, weight training causes muscle inflammation (the soreness you feel afterward), which means the muscle swells from water retention to protect it. The good news is that although weight training, especially when you're just starting out, might cause slight weight gain,В it will help you lose inches-which means even if the number on the scale reads slightly higher, your clothes will fit better.В


Maybe weight gain isn't the only symptom you've noticed. Maybe you feel tired and weak too. It's possible that your thyroid gland isn't making enough thyroid hormone, and that's why you've suddenly noticed an increase in weight. Because the hormone regulates metabolism, people found to have underactive thyroids were also found to have lower basal metabolic rates. If you're not just experiencing weight gain, it could be a good idea to get checked out by a doctor.

PCOS (Polycystic Ovary Syndrome)

As anyone who has been diagnosed with PCOS will tell you, weight gain tends to be on the lesser end of worries caused by this syndrome. Still, due to the stigmas that surround reproductive health, it's easy to glaze over this symptom. Other signs of PCOS include excess body hair, acne, and irregular periods-and unfortunately, some people go a long time without knowing they have it. There are various treatments available, so just like with hypothyroidism, if you think you might have PCOS seeing a doctor is your best bet.

Quitting Smoking


We can extoll the virtues of quitting smoking all day, and the good inarguably outweighs the bad in terms of what it does for your health. However, nicotine is a stimulant and an appetite suppressant: two things that lead to weight decrease. When you quit smoking, your metabolism slows to a normal speed and your appetite comes back. Ultimately these are good things, regardless of the added weight.


Depression can be associated with things we've mentioned before, like medication, stress, and your job. But it also has its own effects on your weight. There are a couple of reasons for this, not least the fact that depression isn't exactly associated with an increased amount of energy. And unfortunately, a lack of exercise exacerbates depression, too. It's a cycle that can be broken by exercising, but not everyone's depression allows for that-it's not a one-size fits all type of thing. So in dealing with this particular weight gain symptom, just do what you know is best for you in order to get better.

Digestive Issues

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There's been more talk lately about the gut microbiome and what it means for your health-not just your gut health, but the rest of your body, too. The bacteria in your digestive tract can dictate everything from how much acne you have to your weight. An imbalance of good and bad bacteria can absolutely lead to sudden weight gain, so you should evaluate the foods you've been eating not just for their general nutritional content but for their probiotic effects. Just taking probiotics can even be a big help!

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Luckily, it's the kind of thing that's just fixed by waiting it out, but getting your period can cause you to gain a little bit of weight. Not only are you retaining water a bit more, but your hormones are all out of whack. Increases in estrogen and progesterone can cause weight fluctuations, and although it's annoying, the most you can do about it is really just wait for it to go away.

An Undiagnosed Medical Condition

Unfortunately, some reasons for sudden weight gain can be a bit more insidious. We've discussed hypothyroidism, PCOS, and depression, all three of which are serious conditions, but there are a litany of conditions associated with rapid weight gain that require immediate medical attention. These include tumors, Cushing disease, and Type 2 diabetes. If you believe that you may be affected by one of these conditions, go see your doctor right away.

Want to learn more about weight gain and how to deal with it? Check outВ what to do when you've realized you've gained five pounds.