Sudden weight gain: What's going on?

I stepped on the scale again today after a bit of a break... and wouldn't you know it, the number is up another two pounds compared to just last week.
Honestly, I am at a total loss here. I’m eating balanced meals, I’m staying active—I'm moving plenty—and yet the scale just keeps creeping upward. It's been happening for a while now.
About three years ago, I was actually underweight for my height. Then, out of nowhere, the weight started piling on. Within a single year, I gained over 20 pounds. If I had just stopped at what most would call an "ideal" weight, everything would be fine, but instead, this slow, steady gain continues.
There isn't any obvious culprit. My diet hasn't undergone any drastic changes, and I haven't suddenly become a couch potato.
Given that other symptoms are pointing toward potential hormonal issues, I have to wonder if there's an underlying imbalance at play.
If anyone else has dealt with something similar, please, let me know.
I'm also looking for advice on how to adjust my nutrition to stop this trend. It feels completely illogical to slash my caloric intake—when I'm already eating a normal, reasonable amount—just to force my weight to stay stagnant.

Megan Williams5 said:I stepped on the scale again today after a bit of a break... and wouldn't you know it, the number is up another two pounds compared to just last week.
Honestly, I am at a total loss here. I’m eating balanced meals, I’m staying active—I'm moving plenty—and yet the scale just keeps creeping upward. It's been happening for a while now.
About three years ago, I was actually underweight for my height. Then, out of nowhere, the weight started piling on. Within a single year, I gained over 20 pounds. If I had just stopped at what most would call an "ideal" weight, everything would be fine, but instead, this slow, steady gain continues.
There isn't any obvious culprit. My diet hasn't undergone any drastic changes, and I haven't suddenly become a couch potato.
Given that other symptoms are pointing toward potential hormonal issues, I have to wonder if there's an underlying imbalance at play.
If anyone else has dealt with something similar, please, let me know.
I'm also looking for advice on how to adjust my nutrition to stop this trend. It feels completely illogical to slash my caloric intake—when I'm already eating a normal, reasonable amount—just to force my weight to stay stagnant.

So, what did the doctor end up saying?

Nothing for now... they just don't believe me when I tell them how much weight I've gained. Before this, I looked practically anorexic. I was eating normally, but I was just terribly thin. Now, I finally look somewhat normal...
I saw my OBGYN regarding some skin issues—she actually referred me to a dermatologist—and since we were already checking my ovaries, everything seemed fine. But then she suggested I could start taking birth control like Yaz to help clear up my skin and regulate my cycles. Everyone seems to criticize those types of pills, so I'm really hesitant to experiment with them. She thinks it's a good move, but I'm nervous...
She didn't even suggest getting my hormone levels checked. I'm going to demand that my primary doctor runs some tests; I'll insist on it because I have no idea why I'm gaining weight, and I fully intend to find the root cause.
Anyway, if anyone else is dealing with similar issues and managed to get things sorted out, please let me know.

Honestly, you should probably go get your thyroid checked out... it might be the reason behind all that weight gain

What kind of checkup are we talking about? Is this a hormone panel or something else entirely?

How tall are you, and what's your weight? I just want to get a baseline so we can establish if you "look pretty much normal" to everyone else.

Who suggested Diane to you? I'm a little confused—was it your OB-GYN or a dermatologist?

Also, which hormones do you think are acting up?

I honestly have no clue which hormones might be out of whack...
So, my skin is a mess, and my dermatologist suggested I go see a gynecologist for an ultrasound just to rule out any issues with my ovaries. Everything there came back fine, but since my cycles are so irregular and my skin is still breaking out, my doctor recommended Diane-35. Has anyone else tried it?

Right now, I’m about 177cm and 65kg...
Technically, that's a perfect BMI, but I still feel like I'm carrying a few extra pounds. I definitely feel more comfortable at around 60kg...
Three years ago, I was only 50kg. Just imagine how frustrating it is to pack on 15kg in three years—with 10 of those coming in a single year—even though my diet hasn't changed and I stay active. It really makes you wonder what's actually going wrong with your body.

I definitely don't want to step on any gynecologist's toes here, but I’ve always felt like those high-dose pills are just a bit too intense
Nowadays, they usually start you off with much lighter options
But honestly, you should probably find a specialist who can walk you through the specifics better than I can

There is so much out there to read about thyroid issues, so definitely do a little digging online regarding symptoms
Your best bet is to ask your primary care doctor for a referral to an endocrinologist and request blood work for thyroid hormones and antibodies
Since waiting lists at places like Mayo Clinic can be such a nightmare lately, it might be easier to just book a private appointment—though, of course, that comes with a price tag

Alright, thanks. I’ll definitely get on that. I was just wondering if anyone here had any personal experiences or advice to share—I’m always open to hearing them.

To be honest, I don't really trust my OBGYN right now because of this... She claims Diane is typically only prescribed for dermatological issues, which is why she's hesitant. And frankly, I agree they seem a bit too harsh, so I'm definitely second-guessing the idea.

Megan Williams5 said:I honestly have no clue which hormones might be out of whack...
So, my skin is a mess, and my dermatologist suggested I go see a gynecologist for an ultrasound just to rule out any issues with my ovaries. Everything there came back fine, but since my cycles are so irregular and my skin is still breaking out, my doctor recommended Diane-35. Has anyone else tried it?

Right now, I’m about 177cm and 65kg...
Technically, that's a perfect BMI, but I still feel like I'm carrying a few extra pounds. I definitely feel more comfortable at around 60kg...
Three years ago, I was only 50kg. Just imagine how frustrating it is to pack on 15kg in three years—with 10 of those coming in a single year—even though my diet hasn't changed and I stay active. It really makes you wonder what's actually going wrong with your body.

Look, don't let that index fool you—it doesn't mean a thing. It completely ignores bone density and organ weight, so...

What should I even say about being 5'5" and 143 lbs?

Megan Williams5 said:I honestly have no clue which hormones might be out of whack...
So, my skin is a mess, and my dermatologist suggested I go see a gynecologist for an ultrasound just to rule out any issues with my ovaries. Everything there came back fine, but since my cycles are so irregular and my skin is still breaking out, my doctor recommended Diane-35. Has anyone else tried it?

Right now, I’m about 177cm and 65kg...
Technically, that's a perfect BMI, but I still feel like I'm carrying a few extra pounds. I definitely feel more comfortable at around 60kg...
Three years ago, I was only 50kg. Just imagine how frustrating it is to pack on 15kg in three years—with 10 of those coming in a single year—even though my diet hasn't changed and I stay active. It really makes you wonder what's actually going wrong with your body.

Look, you basically have three separate issues going on here: irregular cycles, bad skin, and weight gain.
Is your doctor seriously just tossing Diane at you without even checking your hormone levels first? Seriously... wow.
You really need to get your sex hormones and thyroid checked out before you even think about starting something like Diane.

Megan Williams5 said:Nothing for now... they just don't believe me when I tell them how much weight I've gained. Before this, I looked practically anorexic. I was eating normally, but I was just terribly thin. Now, I finally look somewhat normal...
I saw my OBGYN regarding some skin issues—she actually referred me to a dermatologist—and since we were already checking my ovaries, everything seemed fine. But then she suggested I could start taking birth control like Yaz to help clear up my skin and regulate my cycles. Everyone seems to criticize those types of pills, so I'm really hesitant to experiment with them. She thinks it's a good move, but I'm nervous...
She didn't even suggest getting my hormone levels checked. I'm going to demand that my primary doctor runs some tests; I'll insist on it because I have no idea why I'm gaining weight, and I fully intend to find the root cause.
Anyway, if anyone else is dealing with similar issues and managed to get things sorted out, please let me know.

1. Given the skin stuff, it could definitely be PCOS (there's actually a thread about that on here!), and a pelvic ultrasound usually shows things best around day five of your cycle—otherwise, it's hard to see anything—as for the Yaz; those pills can definitely calm down the symptoms, but they can also cause more weight gain, so definitely sleep on it.
2. If you're eating the exact same amount as you were before the weight gain, it could really be a thyroid issue.
In either case—get a referral for an endocrinologist. They'll be the ones to decide which specific hormones need testing and what other labs you should run. At the end of the day, it isn't about how you look, it's about *why* you're gaining weight without any logical explanation. Seriously, ask your doctor what happens if you end up gaining another 30 pounds. 🤷

Look, I’ve got a pretty stupid question here, but I’m honestly spiraling a bit... so I want to hear what you all think.
Is it actually possible to see a 6-pound jump on the scale after just one single day of binge eating? Like, literally in 24 hours?
Thanks.

That weight gain probably isn't a real shift in body mass; besides, home scales aren't exactly precision instruments if you're using them at home.
On top of that, your numbers are going to fluctuate based on how much water you've had throughout the day and whether or not your digestion is keeping up.

Whenever I used to absolutely pig out during my cycle or when I was feeling super depressed, I knew I’d see the scale jump by maybe a kilo or two—I don't think it ever hit three... but then the next day, it would just drop back down. My body probably just resets overnight or whatever. And like Emily Rodriguez9 mentioned, digestion and staying hydrated really matter on those days.
One liter of water is basically a kilo. Just do the math. It might even be because of her.

I’ve been feeling pretty desperate lately, so I figured I’d just put this out there and ask.

I’m 26 years old, 5'7", and weigh about 120 lbs. I know that’s not a massive amount for my height (even though I saw some site online claiming my "ideal" weight was 110 lbs!!!!). The thing is, for the last few years, I was consistently sitting right at 110 lbs. Personally, I felt like that was actually too low, so my goal was really more like 115 lbs. But even though I haven't changed what I eat or how much I move, my weight suddenly jumped up to 120 lbs. I noticed a huge difference in my stomach area—I never had a totally flat stomach, but now it feels massive. I just chalked it up to bloating or PMS, you know? But even after those days pass, neither the bloat nor the weight has budged an inch. I eventually convinced myself I’d just subconsciously eaten a bit more, and honestly, I didn't think it was a big deal since I could probably drop a couple of pounds in a week or two. I did cut back on food slightly (not drastically, since I don't eat much to begin with) and moved around more, but it hasn't done anything to my weight. I wasn't expecting a miracle, but I thought I might at least lose half a pound or a pound in a week. To make matters weirder, the exact same thing happened to my sister when she was my age. She gained 22 lbs in just a few days. I thought she was exaggerating or just eating more without realizing it, but now the same thing is happening to me—though on a much smaller scale, even though I’ve always been significantly lighter than her.

So, let me emphasize: the issue isn't that I'm 120 lbs. The real issue is that I gained 9 lbs in just a few days, despite not eating extra calories and keeping my activity levels exactly the same. Another weird part? Cutting calories and moving more hasn't had any effect on my weight at all (and yeah, this happened to my sister, too). Even though it's only 9 lbs, I can literally feel it.

I’m honestly scared of what comes next. I’d go see a doctor, but my primary care physician is impossible to talk to; even if you're in a crisis, she brushes everything off as "nothing," so there's no way she'd listen to something like this.

So, if anyone has any smart suggestions, please share them with me.

Thanks to everyone for sticking through this long-winded update! 🙏

First off, there is zero chance that 110 pounds is your ideal weight.

Second, you didn't just magically gain four pounds overnight. It doesn't work like that. If you're seeing extra weight specifically around your stomach, you might actually be pregnant.

Third, take a second to actually process what I just said. Accept the facts, because they're true. Period.

And as for your sister? There is no way she put on twenty pounds in a few days unless she was lugging around a heavy bag of Quikrete on her back.

Carol Wilson5 said:I’ve been feeling pretty desperate lately, so I figured I’d just put this out there and ask.

I’m 26 years old, 5'7", and weigh about 120 lbs. I know that’s not a massive amount for my height (even though I saw some site online claiming my "ideal" weight was 110 lbs!!!!). The thing is, for the last few years, I was consistently sitting right at 110 lbs. Personally, I felt like that was actually too low, so my goal was really more like 115 lbs. But even though I haven't changed what I eat or how much I move, my weight suddenly jumped up to 120 lbs. I noticed a huge difference in my stomach area—I never had a totally flat stomach, but now it feels massive. I just chalked it up to bloating or PMS, you know? But even after those days pass, neither the bloat nor the weight has budged an inch. I eventually convinced myself I’d just subconsciously eaten a bit more, and honestly, I didn't think it was a big deal since I could probably drop a couple of pounds in a week or two. I did cut back on food slightly (not drastically, since I don't eat much to begin with) and moved around more, but it hasn't done anything to my weight. I wasn't expecting a miracle, but I thought I might at least lose half a pound or a pound in a week. To make matters weirder, the exact same thing happened to my sister when she was my age. She gained 22 lbs in just a few days. I thought she was exaggerating or just eating more without realizing it, but now the same thing is happening to me—though on a much smaller scale, even though I’ve always been significantly lighter than her.

So, let me emphasize: the issue isn't that I'm 120 lbs. The real issue is that I gained 9 lbs in just a few days, despite not eating extra calories and keeping my activity levels exactly the same. Another weird part? Cutting calories and moving more hasn't had any effect on my weight at all (and yeah, this happened to my sister, too). Even though it's only 9 lbs, I can literally feel it.

I’m honestly scared of what comes next. I’d go see a doctor, but my primary care physician is impossible to talk to; even if you're in a crisis, she brushes everything off as "nothing," so there's no way she'd listen to something like this.

So, if anyone has any smart suggestions, please share them with me.

Thanks to everyone for sticking through this long-winded update! 🙏

I’m with stormyheron4 on all four points here—it's been a while since I actually agreed with someone 😁, but they nailed it!

I’ll just add a few more numbers to help with that whole thin vs. overweight dilemma.

Look, at 120 lbs and 5'7", you're right on the edge of being classified as anorexic.

Your BMI is already sitting slightly under 19 with that weight (and 19 is basically the floor for BMI standards established back in the day), whereas for your age, it really ought to be somewhere between 20 and 25.

Bottom line? You're underweight right now.

(For context, I'm 5'4" and used to be 120 lbs before I had kids, and I was considered super slim.)

stormyheron4 said:First off, there is zero chance that 110 pounds is your ideal weight.

Second, you didn't just magically gain four pounds overnight. It doesn't work like that. If you're seeing extra weight specifically around your stomach, you might actually be pregnant.

Third, take a second to actually process what I just said. Accept the facts, because they're true. Period.

And as for your sister? There is no way she put on twenty pounds in a few days unless she was lugging around a heavy bag of Quikrete on her back.

I’m not sure what caused the sudden weight gain Carol Wilson5 mentioned, but I have to disagree with the points made above.
When I broke my leg two years ago, I gained six pounds in a single week. I couldn't believe it when I stepped on the scale. Sure, I wasn't moving much because of the cast, but trying to get around on crutches is exhausting work...
So, the theory that gaining three or four pounds in a week is impossible just isn't true.
But, like I said, I really don't know how someone's weight can spike so quickly without any changes to their diet or activity levels.

Roger Rodriguez said:I’m not sure what caused the sudden weight gain Carol Wilson5 mentioned, but I have to disagree with the points made above.
When I broke my leg two years ago, I gained six pounds in a single week. I couldn't believe it when I stepped on the scale. Sure, I wasn't moving much because of the cast, but trying to get around on crutches is exhausting work...
So, the theory that gaining three or four pounds in a week is impossible just isn't true.
But, like I said, I really don't know how someone's weight can spike so quickly without any changes to their diet or activity levels.

Were you weighing yourself while wearing the cast?
Sorry if that's a stupid question 😁