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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Sister is 55 and suddenly obsessed with her weight

100 replies

youlookradishing · 14/05/2026 10:41

She’s always been ‘normal’ weight, typical 5ft 5 size 10-12. She’s been happily married for over 30 years and has had 3 children, just for context.

We used to have normal conversations about a range of interesting stuff. She’s always been a bit rigid and moralistic about things, but it’s just her personality.

Over the past 2 years or so though she’s become obsessed with her weight and being slim. Most conversations will include comments about how X or Y food isn’t good for you or how she eats 30 different grains a day or whatever. She’s not bothered about her ‘looks’ per se, she never wears makeup and doesn’t spend much on clothes, but she’s now a very slim size 8. She tries to persuade me that if we have a ‘big breakfast’ (by which she means several slices of toast and a piece of fruit) then we won’t ‘need’ lunch. If we go out for a meal she will have a salad without fail and she runs 5k every morning. She says this is all about being healthy, but she is always weighing herself on the fat / bmi machines in Boots. Her bmi is now about 18.5 so verging on underweight.

She casts judgement on others and seems to be using this as a way of making herself feel good in comparison. She’ll tell me that a certain celebrity now looks “awful” and when I google them they actually look fine, they just got older and put on some weight. Or comment to me about how a certain friend “eats doughnuts” as though it’s something she expects me to be aghast about.

Anyway I’m not sure what I’m asking here: I’m a bit nonplussed because I recognise some this attitude from my teens in the early 00s when sneering at ‘fat people’ was unfortunately more of a mainstream attitude and being double size zero was held up as a virtue.

But she’s 55 years old! This seems to have come from nowhere as she had a normal attitude about weight until now (or so I assume). She grew up in the 80s which I know were an unhealthy era for body image, but that was a long time ago now and there is more body size acceptance today than ever before!

I suppose I’m asking anyone if they recognise this pattern of behaviour? Could it be menopause related? She’s also just taken early retirement (at the same time as her husband, who is 60), is she having an identity crisis?!

(I do know the obvious answer is to speak to her, but I don’t see her that often, we are not v close in age and live some distance apart, in the meantime I’m just interested to know what you think and whether you’ve known this happen to anyone in your lives?)

OP posts:
hazelnutvanillalatte · 14/05/2026 11:38

EDs are thought of as a teenage thing, but they can start/flare up at any age. Retirement and menopause can be triggers as they can inspire a desire for control in the face of change. I would gently challenge some of what she says - not in an argumentative way, but her thinking may be distorted, and need to be brought back to reality - food is fuel, and you need to fuel yourself properly to stay healthy.

MsGreying · 14/05/2026 11:41

You can either ignore and change the subject or say "You're talking a lot about food at the moment. Is everything OK?"

Fibrous · 14/05/2026 11:45

MeridaBrave · 14/05/2026 11:36

I’d be saying that it’s not healthy to be obsessed about weight without considering muscle mass - and with BMI of 18.5 she is at risk of low muscle mass. I’d be encouraging her to do a dexa scan esp if the exercise is running rather than weight training.

I agree with this. It's great she's taking an interest in her health, but I'm not sure she's going about it the right way and could be causing herself damage.

Bestfootforward11 · 14/05/2026 11:45

Potentially menopause and the realisation of the impact of aging on your body. I’m 50 and things are aching and creaking that did not before. I want to be physically capable for as long as possible. Having been slim all my life I’m carrying extra weight which is likely impacting my knees (along with other things!). I know lots of women in this age range really commiting to exercises and healthy diets. I don’t know the detail of your sister but it could be along those lines.

BillieWiper · 14/05/2026 11:49

She sounds dreadfully dull droning on about it all and talking about donuts like they're the equivalent of sharing a crack pipe with a hantavirus sufferer?!

Be as skinny, 'healthy' as you like but nobody else is interested! I'd try and avoid seeing her tbh.

And if I do I would say firmly that you have interest in her food intake and it's rude to comment on other people's. That she should just be glad she can afford food at all as some people are starving to death in war zones!

ShorterMumma · 14/05/2026 11:49

She sounds anxious - menopause? Is she on HRT?

I get where shes coming from as ive always been slim and as my name suggests, I'm short so even a few kg shows on me. I've never eaten as well as I do now.

But I don't talk about it.

Have you tried talking to her about this?

Vroomfondleswaistcoat · 14/05/2026 11:51

Does she have any hobbies or interests? Because it sounds as though she's take up 'What I weigh' as her new life interest, having retired. It's easily done, without workmates to bounce conversation off (and also to tell you that you're being boring, you look fine) and nothing to throw your life into - particularly if you've had any kind of history of weight restriction.

Are there grandchildren on the horizon, or any time-consuming activities that she could be encouraged to put her brain power into?

Chasbo · 14/05/2026 11:52

Orthorexia tipping into something else.

You can't fix this.

But you could observe it's much better to have a slightly higher BMI range as you age, as it's protective to have enough muscle and fat.

Any PT or coach would say that rest days are very important too.

Notonthestairs · 14/05/2026 11:52

If this was just about her health surely she wouldn’t be bothering to cast aspersions on other peoples choices/bodies.

Jibaka · 14/05/2026 11:52

She needs to be careful re nutrients. I know lots of women that age who are fighting to be thin. They are on mj, suffering hair loss and thinning bones. Weight isn’t necessarily an indicator of health at that age. It’s difficult because it’s very easy during menopause to stack loads of weight on which isn’t great either.

JLou08 · 14/05/2026 11:54

Eating 30 is nothing to do with weight. It could genuinely be a desire to be healthy, her own mortality is probably more at the forefront at her age and she's doing what she can to have a long healthy life. BMI does matter for health, it's not just about how we look.
You can't compare it to how you was as a teen. When we're that age we usually feel invincible and care more about looks than health. That changes as we get older and start to notice are energy and fitness change and start to have people around us being diagnosed with health issues.

CandidOP · 14/05/2026 11:55

I have always kept an eye on my weight - the legacy of having a very overweight mother, but since hitting 60 and reading Ultra Processed People I have become much more aware of what I am eating. I have a chronic auto immune condition that causes inflammation and unfortunately have to take some very strong drugs which thankfully enable me to lead a good life. This has all led me think much more about my diet rather than just have a desire for my body to be thin. I try and eat more fibre, have a couple of carb free days a week and not eat too many UPF's. I expect my family think I am a bit of a bore and my mother definitely thinks I am annoying as I refuse yet another piece of industrialised food. I want whatever my remaining lifespan is to be as healthy and mobile as possible. I suspect that might be what lies behind your sister's changing lifestyle and attitude. I hope it pays off for her.

TheGoddessFrigg · 14/05/2026 11:57

it wasnt until I got to this age that I suddenly realized I NEEDED to think about losing weight. I had always been underweight all my life then in my 50s a triple whammy of menopause, disability and medication side effects hot me like a wrecking ball. It's not because I suddenly wanted to attract male attention- Im glad to see the back of all that!
Perhaps your sister wants to invest in herself now

oncemoreuntothebeachdearfriends · 14/05/2026 11:58

If a man suddenly started looking after himself, the assumption on MN would be he's having an affair .

Safarisagoody · 14/05/2026 11:58

I’d say it’s retirement telling her she ageing, so she’s now focusing on health. As from what you’ve written it is not about weight, it’s about whay she and others consumes.

Jenkibuble · 14/05/2026 11:58

Her appetite may have dropped - mine definitely has (45) and I will often skip lunch or dinner if I have sufficient nutrition at other meals.

Fasting has been shown to have benefits.

Is the food that she does eat of good nutritional quality ?

As PP mentioned, osteoporosis is a worry.

That said, so long as it isnt an ED, it is easier to put on weight than lose it .
She sounds mindful and responsible .

Idlewilder · 14/05/2026 12:01

Has she done Zoe? A lot of middle aged women became very evangelical about it a couple of years ago. It combined the latest scientific research with some expensive testing and tracking - blood sugar, cholesterol, response to fats - and definitely lent itself to a bit of an obsession. Zoe definitely promotes the 30 a day thing too.

There are probably worse thing to happen in middle age - it's not unheard of to have an injury or some setbacks, pile weight on and find yourself practically immobile in your sixties. But the evangelism and judgement are hard for those of us who like our little indulgences.

Additup · 14/05/2026 12:08

Wanting to be healthy and eat healthy food and take exercise is great at any age. Skipping meals rather than eating a healthy balanced diet is really not great (at any age). IMO your sister is verging into eating disorder territory if she isn't there already.

Does your sister struggle with how her life is going because in my experience EDs are usually about control rather than a desire to lose weight.

Calliopespa · 14/05/2026 12:10

youlookradishing · 14/05/2026 10:53

I guess I am worried about it being disordered in some way, even if not a full blown eating disorder.

But I guess I also just want to understand. Last time my behaviour was anything like hers I was an insecure teen who wanted boys to fancy me and girls not to bitch about me. I struggle to see where it’s coming from with her.

Edited

I think you have hit the nail on the head with insecurity - which, of course can come in many forms, not just wanting the boys to like you.

55 and taking retirement is a stage at which she will be experiencing changes, both bodily and otherwise, and the weight fixation sounds like a way to control this experience of change.

Also, retirement will mean she has more head space (and actual time) to obsess over it. The most weight-conscious people I know tend to have fewer hobbies etc, and I do think that can feed into it.

At her age 18.5 bmi is quite alarmingly low. I was round that for many years up until my early 30's and, in hindsight, it was too low for me even then. Has she seen the smart BMI calculators which treat weight gain as you age as not necessarily unhealthy?

EmeraldShamrock000 · 14/05/2026 12:12

It’s her new project, she’s probably a little obsessed about it but in her defence a lot of people who eat well and train are very vocal about their achievements.
She doesn’t need to be nasty or controlling towards others but she’s strength building. I wish I was motivated enough to do 1km every morning or even weekly.

youlookradishing · 14/05/2026 12:12

She has always been a bit of a control freak to be honest so I think you are right that this must be a part of it.
She’s one of those people who can’t function without a plan, CANNOT be late, packs her suitcase a week before she goes away and would rather do everything herself than delegate.

OP posts:
Calliopespa · 14/05/2026 12:15

youlookradishing · 14/05/2026 12:12

She has always been a bit of a control freak to be honest so I think you are right that this must be a part of it.
She’s one of those people who can’t function without a plan, CANNOT be late, packs her suitcase a week before she goes away and would rather do everything herself than delegate.

Yes, I think it sounds like control at a time of ineveitable change.

Pinribbons · 14/05/2026 12:16

I'm 56 and finding, despite being very active, and loving my food, that I only need/want 2 meals a day, especially if it's a "proper" breakfast mid morning, I won't want anything else until an early dinner.

suki1964 · 14/05/2026 12:25

I started to take more interest in weight, exercise and healthier eating in my late 50's

Menopause and injury and depression, I had ballooned so I stated to look at what I was eating, how little I was moving, and Ive made changes

I guess I bored the pants of others for the first few years

And yes I won't eat lunch if I have had breakfast, I eat more plants then I ever have in my life , eat grains etc , as we age we dont need to eat so much. I dont go hungry, I eat when Im hungry and eat until Im full and that's it

It takes a lot more work to keep trim and fit at this age , and the way the NHS is, I have to do the best I can for myself

Calliopespa · 14/05/2026 12:27

Lots of people are saying she is perhaps educating herself on health, but to be honest several pieces of toast plus fruit is quite a carb heavy breakfast at any age. Without some eggs or similar (and probably less toast), as well as her bmi obsession, it sounds more like she's gone down some rabbit hole of her own rather than that she is building a healthy body for going forward as a positive thing. I mean it's impossible to tell from a thread OP, but if you said "my sister has decided to avoid upfs where possible, incorporate daily exercise and muscle building, as well as take note of her protein intake, I'd feel it was more a rational response to taking care of herself.