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AIBU?

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Original poster

To think my son isn't fat

210 replies

GeorgeandTimmy21 · 07/11/2026 15:09

I know lots of parents are in denial about this sort of thing but I honestly don't think I am. He is 18 years old, wearing size medium t shirts and 34 inch waist trousers. He weighs 11 stone and I'm not sure exactly how tall he is, less than 6ft but not much less. He runs 10k 2 times a week and 5k 2 times a week. My MIL thinks he is fat (for context my MIL is a size 18).

OP posts:
faithfultoGeorgeMichael · 07/11/2026 15:10

What is his BMI? It is not a good measure for athletes but is generally a good ball park for regular folk

Scottishskifun · 07/11/2026 15:11

Definitely doesn't sound it by your description. I would just tell your MIL to stop commenting or even better get your husband to have a word with her.

It's not acceptable to comment on people's weight male or female.

Thedam · 07/11/2026 15:11

You don’t know your son’s height? Are we talking 5’5 or 5’11?

PimblePumble · 07/11/2026 15:11

Why are you asking, did someone call him fat?

Thedam · 07/11/2026 15:11

PimblePumble · 07/11/2026 15:11

Why are you asking, did someone call him fat?

It’s a very short Op

QuirkyHorse · 07/11/2026 15:12

Tell you mil it is absolutely none of her business!
He doesn't sound fat to me (sounds similar to what DH weighs)

BagaChips · 07/11/2026 15:13

PimblePumble · 07/11/2026 15:11

Why are you asking, did someone call him fat?

You only had to read 5 sentences

Original poster
GeorgeandTimmy21 · 07/11/2026 15:13

MIL called him fat. Haven't worked out his BMI. At a guess he is around 5ft 10inches.

OP posts:
Alittlefrustrated · 07/11/2026 15:14

PimblePumble · 07/11/2026 15:11

Why are you asking, did someone call him fat?

Read the OP

twoyearsleft · 07/11/2026 15:15

I would say waist 34 is entering being a bit fat.

My 18 yr old is 6ft 4” with a 30” waist.

LittleGreenShoots · 07/11/2026 15:15

Does he have a noticeable belly in t shirts? a jiggle of fat in his belly/ arms when he moves? I feel like these are really what people mean when they say fat.

Thedam · 07/11/2026 15:16

What does his dad think?

twoyearsleft · 07/11/2026 15:16

GeorgeandTimmy21 · 07/11/2026 15:13

MIL called him fat. Haven't worked out his BMI. At a guess he is around 5ft 10inches.

My DH is the same height as your DS and he was definitely fat when he was wearing waist 34”. He’s now waist 30” and looks so much better and in proportion.

JoleneJoleneJoleneJoleneJolene · 07/11/2026 15:17

twoyearsleft · 07/11/2026 15:15

I would say waist 34 is entering being a bit fat.

My 18 yr old is 6ft 4” with a 30” waist.

This is whats in the dictionary when you look up 'Mumsnet'

time4anothername · 07/11/2026 15:18

waist to height ratio is being cited as a more important health indicator than bmi.If he is 5 10 then 34 inches does not indicate a health risk.
Forget "fat" - if he has energy and feels good, regular bowel movements etc, that is what matters

Cheese55 · 07/11/2026 15:18

GeorgeandTimmy21 · 07/11/2026 15:09

I know lots of parents are in denial about this sort of thing but I honestly don't think I am. He is 18 years old, wearing size medium t shirts and 34 inch waist trousers. He weighs 11 stone and I'm not sure exactly how tall he is, less than 6ft but not much less. He runs 10k 2 times a week and 5k 2 times a week. My MIL thinks he is fat (for context my MIL is a size 18).

I can be 10st 10 and still be within my BMI and I'm a 5ft.5 female. Unless he's shorter than me he can't be fat.

WilmaaFlintstone · 07/11/2026 15:18

Who cares?

He's an adult, you should've closed the conversation down immediately.

It's nothing to do with your MIL.

Vermy · 07/11/2026 15:19

He doesn’t sound overweight at all. At 11 stone and under 6ft, especially with that level of running, he sounds perfectly healthy. His grandmother shouldn’t be making comments about his body.

EmeraldShamrock000 · 07/11/2026 15:20

No. It doesn’t seem like he is as he is active too. Your MIL might be a bit delusional. Why would she say such a thing about him? Has she been nasty in the past? Did you tell her she was fat? I might have in this situation. 🫣

SethAndReubenTooSendGaloshes · 07/11/2026 15:20

twoyearsleft · 07/11/2026 15:15

I would say waist 34 is entering being a bit fat.

My 18 yr old is 6ft 4” with a 30” waist.

Mine isn't far off that height and the same waist but he's too thin and doesn't eat enough to fuel his activity levels. Being skinny for a teenage boy is not ideal either.

OP that's a BMI of 21-22, so bang on healthy.

EppingIsFun · 07/11/2026 15:21

Your MIL sounds horrible. Hope she isn't saying it to his face. If she carries on, suggest to her that she and DS do a weight loss programme together - perhaps she'd like to join him on his runs. You don't need to say that to him, of course.

34 inch waist is not fat - that's ridiculous. As are the posters suggesting it is.

Merryoldgoat · 07/11/2026 15:23

There is no way an adult male weighing 11 stone at 5’ 10” is ’fat’

This place is a fucking menace sometimes.

Fluffypiki · 07/11/2026 15:27

Meanwhile according to the NHS my 18 year old kid is "perfect" and yet he looks like a (very cute) shrimp. Bah he is active and waistline means nothing, he could be wearing 34 in m&s and 30 in Asda. You should only care if he is happy in his own skin.

bigboykitty · 07/11/2026 15:28

He can't be fat at 11 stone and approx 5'10 given that he's really active. Maybe shut your MIL up by saying 'no MIL, it's you who's fat. Please don't bring it up again unless you'd like another truth bomb about your own weight issues'.