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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Teen rapidly gaining weight

15 replies

Wildflowerwonder · 08/01/2026 12:02

DD15 has rapidly gained weight since last summer (10kg). She is as active as ever and hasn’t changed her diet. She hasn’t grown any taller, it all seems to be going to her stomach area (she’s not pregnant, before anyone suggests that!).

Has anyone had any luck in addressing this with the GP? What sort of action should I expect them to take? I have a friend in a similar situation and the GP just totally brushed off her concerns as ‘growing pains’ etc), but my child is getting increasingly upset by the situation. I am concerned she might get stuck in a metabolic situation where she will be unable to lose weight. She has always been a hungry child and has always been large, but this gain is abnormal even for her.

is there anyone privately who might address this? Not sure what sort of medical professional would look at this. We are Manchester based if that helps.

OP posts:
moondip · 08/01/2026 12:05

My first thought is that it could be endocrinological. Could you search for private endocrinologists in your area that might do blood tests to check how her hormones are behaving and rule in/out things like PCOS?

InfoSecInTheCity · 08/01/2026 12:09

They are unlikely to diagnose PCOS as a teenager because hormone levels are all over the place during these years and because getting a doctor to diagnose PCOS is often a challenge anyway, they do like to fob off women’s troubles, but I’d be inclined towards treating it anyway by following a low GI diet and following advice for T2 diabetes such as increasing activity after a meal (brisk walk, YouTube video etc) to improve breakdown of glucose.

5128gap · 08/01/2026 12:21

If you're absolutely certain her food intake hasn't increased and her excercise levels haven't dropped, then it needs investigating. Particularly as all the weight is going onto her stomach rather than evenly spread across her body. Tell the GP she has gained 10kg on her stomach in 6 months with no changes to diet or excercise and don't be fobbed off.

Glittertwins · 08/01/2026 12:23

They certainly can check for PCOS. My DD was.

momahoho1 · 08/01/2026 12:28

I would be trying to make sure that there’s no secret eating as that’s the far more likely reason combined with a lower calorific requirement as has reached adult height. My dsd gained rapidly because once into that age group overall activity declined (still did sport but less general exercise) and was snacking way too much. I can into her life a bit later but the amount of crisp packets, fizzy drinks and chocolate bars was a shock, dh was shocked too as we think she hit it from them when she was younger but never did from me. Impulse control is the issue (and in other parts of life too).

if it’s definitely not less exercise, sneaking food or needing less calories then go to the doctor but they will be thinking along these lines at first

Puddingpiper · 08/01/2026 12:31

Three possibilities:

  1. she is pregnant
  2. she is eating far more than you think
  3. she is very ill

Answer to 1, 2 and 3 is to consult the GP and be insistent they do all tests and refer to specialist for either maternity, disordered eating/therapy or diagnostics.

MrsSPenguins · 08/01/2026 12:34

Has she added any drinks? Like that's around 400 calories a day and could be just adding one hot chocolate, one energy drink a day whilst she exercises. There don't have to be massive changes in diet.

If you are absolutely certain there has been no change in calories in and out (food diary might help) then push for more tests. Sugar and salt can give temporary weight gain though not that amount. If she's trying to lose weight then reducing sugar helps.

tentonnetruck · 08/01/2026 12:34

As the mother of two teens who eat a ridiculous amount of crap outside of the home, can you say for certain that her diet hasn’t changed? Where we live, going to the chicken shop is a standard teen activity. I also find wrappers for large bags of sweets and chocolate bars fairly regularly. We have frequent conversations about the health implications but I’m not sure how much it sinks in.
if you are absolutely sure she’s not changed her diet, then definitely take her to the GP.

tentonnetruck · 08/01/2026 12:36

I would also say, if she’s reached her adult height already, then she may not be able to get away with eating what she was when she was still growing.

JDM625 · 08/01/2026 12:37

Vaguely similar to me at that age. I was always tall but when I hit puberty, I stopped growing taller and grew outwards. Suddenly had boobs and hips. In my case though, I just wasn't doing enough exercise/not eating great things at school and had no health issues. I also got stretch marks which my thin mum had never seen in her life. Whatever you do, don't ask the GP what they are in front of your DD. I still recall the humiliation.

I too would be speaking to the GP, or a different GP at your practice if one has been dismissive. It does seem odd to be getting tummy fat but no where else!

TheWonderhorse · 08/01/2026 12:42

I think 1.5 stone in 6 months is quite concerning but you absolutely need to tackle this sensitively. If it is that she's eating more or exercising less the last thing you want to do is shame her.

Does she have any other symptoms? Pain? Fatigue? Are her periods normal?

MrsSPenguins · 08/01/2026 12:48

The other thing to watch out for that are really common at this age as there's a whole load of pressure at school at this age is declining mental health. This would not directly cause it but could indirectly if you comfort eat or drink or just don't look at calories - like 1 drink could be pretty much 0 calories, another 600.

Wildflowerwonder · 08/01/2026 12:53

Thanks for all the tips. I think we’ll do a food diary for a month or so and then go back to the GP with the results.

OP posts:
ShortAndIntense · 08/01/2026 13:05

Please check for PCOS. This sounds exactly like me and I was utterly miserable as a teenager and through my 20s unable to lose weight unless I was eating 800 calories a day - and then my hair would fall out due to lack of nutrition.
Lo and behold, started trying for a baby at 28 years old - bam! PCOS diagnosis. I’ve been on Metformin since and it is literally a life changer for me. I have to eat well, cut carbs and exercise, but I feel normal for the first time in my life. I wish I was diagnosed sooner.

Justlostmybagel · 08/01/2026 13:07

How certain are you that she's not pregnant? Have you done a test with her?

Whatever it is, it sounds like she needs a GP appointment.

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