Husband's extreme diet is worrying

He's not a teenager, is he. Adult male capable of making his own decisions and doing research etc.
If he was eating cotton buds I would be worried but you don't lose weight on carnivore diet unless you are over weight/obese.
It's not a diet with life threatening consequences as meat (and eggs) is obviously high in protein, healthy fats and full of micronutrients.
It's a boring and socially awkward diet but not harmful, especially after 5 minutes.
My point was to reassure OP, I never met or heard of anyone having any health issues from it. He will probably get bored of it soon anyway.
If he has obsessive eating habits in general this is probably much lesser evil than other extreme diets (or in this case extremely boring).
I'm not interested in arguing with randoms on the internet, so unless OP is appointing you as her spokesperson, take a hike.

Her husband is nine stone and has obsessive eating habits. You just going 'it's a few days and it's a magic diet' is not helpful. If she had said her very underweight teenage daughter with obsessive food habits was doing this would you say crack on, doesn't sound like problem at all why are you so het up?

Yes, what's your point?

Have you actually read her posts?

He will be fine OP.
I was on carnivore diet for 4 years pretty much before anyone in the UK even heard about it.
It never did me any harm whatsoever.
It's boring, very VERY boring, but that's about it. Some people do very well on it but most get so bored with it and they stop.
He's been on it for 5 minutes, it won't kill him.

He doesn't necessarily have an eating disorder and isn't necessarily too thin but it sounds like he has a number of unmanaged health conditions that would be worth exploration by someone qualified. That might not be a GP but it would be a good place to start. I think you should take him up on the "I'll go if you make me" and he should be clear about how many exclusions he's having to make in order to feel well. It's not normal and a decent GP should want to explore what's going on.

Separately, I would talk to him about the importance of raising your dc with healthy attitudes towards food and how important meal times together are. He doesn't have to eat the same food, or even eat at all but he does have to come to the table and participate in the family time together.

My dh has always been erratic with his food likes and dislikes and has a very all or nothing approach to food. In recent month, this has got more extreme. He is now on the carnivore diet and it mostly eating mince, eggs and chicken. He was eating porridge, veg, fruit, nuts and kefir a few weeks ago but he's now eliminated those too. He won't eat potatoes or grains now and very very rarely will he ever have a treat. If he does, it's something like a bit of 85% dark chocolate.

He's 37, 5ft 10 and just over 9 stone. So he's underweight. He says he's doing this to heal his gut as he has self diagnosed leaky gut. As long as I've known him he's had flair ups of ibs but I believe that's more down to his anxiety. He has some complex ptsd and anxiety problems, long term.

I've asked him to see a doctor which he seems reluctant to do and will say things like, I'll go if YOU want me to. Meaning he'll do it to get me off his back! He's still not been yet.

He's constantly looking food stuff up on his phone and watching American 'experts' taking about these diets on YouTube. He reads all food packaging intensely and critisies it, even if he's not the one eating it!

His eating is extreme and totally obsessive. His mood is also very effected by food and he gets incredibly 'hangry' yet he also does a bit of intermittent fasting which makes that worse. Sometimes he'll go to work and not eat until he gets home at 5pm. That's not everyday but at least 2 times a week.

I've got to the point where I'm really getting worried about this. I'm scared what he's doing to himself in the short term and long term but he just won't hear it. He dismisses red meat and certain cancers and dismisses high cholesterol with high fat diets, saying that both those things are now unfounded. The problem is he's getting his so called facts from sources that I would not see at reputable.

It's effecting our family life now. We have two young children and rarely eat together at home because he eats and cooks such different things to us. The children and myself eating a moderate, healthy diet with an occasional treat. Last week our 3yo actually questioned why he wasn't eating breakfast or lunch when we were on holiday. It's scary to see someone you love do this to themselves when they are also in denial that there's a problem and that he's in the right and the rest of us are totally wrong. I think this is a type of eating disorder now or health anxiety. He's become very serious because of all this and isn't himself, it's actually really sad.
Aibu? What should I do?

There are plenty of Doctors and scientists who follow the carnivore diet, and have been for years with health benefits.
Dr Paul Mason
Dr Anthony Chaffee
Dr Robert Kiltz
Dr Zsofia Clemmens
Dr Shawn Baker
Dr Robert Cywese
Dr Chaffee has a podcast called the plant free MD and interviews Drs, scientists and patients who have had success with carnivore

Galwaygirlxxx curious if you believe that the many doctors who follow this way of eating have disordered eating?

I’ve done lots of reading about these keto style diets and fasting and there are some fascinating health benefits. I’d try supporting him in that front putting aside my own worries about not getting 5 a day! But address the moods and obsessiveness that’s affecting your family.