To gain weight intentionally?

What about having a smoothie/milkshake as a snack ? Eg liquidise banana , milk and another fruit or peanut butter for taste. And slightly increase portion for your evening meal - do you mean 4 mini new potatoes ? That's not much . Perhaps do mash instead with butter and cheese.

I suppose that’s the thing - are you adding butter/sauces etc

I think you should just do a review over the next couple of days. Maybe weigh things out so you can see

I can only imagine it’s portion size. My dd is a teen and she just doesn’t really get that hungry or take pleasure in food. So she eats until she is full and that’s it. She is hovering around being under weight so I try and encourage one more mouthful or one more potato and after school I will encourage her to have a sandwich or some biscuits.

I have a friend like you, who claims to eat normally but her view is skewed! Been on several holidays with her over the years, big group ones with kids and adults and I’d say she eats about a third of what the other adults do.

If you’re not motivated by hunger it’s hard to eat. That’s a small portion and what I might eat, but I’d have some sauce on the chicken which adds calories.

Yes I’m not great with these either but according to MyFitnessPal that comes out at around 500 calories which isn’t great if it’s your biggest meal of the day

is that what you computed it as?

I hesitate to poke my head above the parapet here as MN tends to be a bit weird about the subject of food.

But the size of that meal sounds a bit small to me for dinner. I'd definitely still feel hungry afterwards - unless I'd had an enormous lunch.

How much exercise do you take OP? Moving tends to boost your appetite so you might feel able to eat slightly larger portions without feeling stuffed.

maybe some collagen supplements for your skin and feroglobin and vitamin d for the tiredness.

Being too thin is not a problem I'm ever likely to have! But there is absolutely nothing weird or wrong with wanting to gain weight intentionally - if you feel you're too thin, or that your size is connected to feeling weak or lacking in energy, then it's perfectly sensible and healthy to be considering trying to gain a bit of weight.

A friend of mine (a bloke, but same rules apply) was always quite slim and wiry, but he became very thin after a very serious illness and when he didn't start to put weight on once he'd recovered, he was advised to continue eating a healthy and balanced diet but to ramp up the more nutrient dense elements. Basically, plenty of protein, healthy fats, and a decent amount of carbs. I remember him eating a lot of oily fish, upping the red meat a bit, lots of things like full-fat yogurt and full-fat cream cheese, peanut butter, olive oil, eggs, nut-based snacks, porridge made with whole milk etc. Plus all the usual fruit and veg. Exercise-wise, he joined a gym and focused a lot on strength rather than cardio so he was building muscle.

His doctors also said that, if he was still struggling to gain weight, they might suggest he start having protein shakes in addition to his normal meals, but he didn't need to do that in the end.

You don’t say how old your kids are but how do your portions stack up against the rest of your family?

think of a plate - say a chicken breast, new potatoes and broccoli florets. How much Do you have of each?

I would see the GP though as it is important you Rule out any other Deficiencies/issues

Are you tall? Have you been to GP to make sure nothing else is going on?

I would imagine your portion size is a lot smaller than you think (opposite to most people problem!). All the people o know who are veering to underweight are convinced they eat like a horse but whenever we meet they always alter the meal to reduce carbs in particular or have a salad but ask for no dressing.

eg you say you eat dark chocolate - how much do you eat of an evening?

as with people who need to lose weight I think you need to do an honest assessment over a few days

I would say a really great place to start is to assess your current diet objectively - you could post it here to get outside opinions. It's really common for our perception of 'good' and 'healthy' and 'enough' to be warped by lots of different factors and reasons, and it's very easy to fall into habits - how often do you stop and look at your diet enough to remember what you ate for the last two weeks - I know I'd struggle! Rather than a short term 'okay I need to eat burgers twice a week' it's better to look at your current diet and go 'actually, I don't eat until 11am and then just have a 3 egg omelette, breakfast too early makes me nauseous, so maybe I could add some ham or beans or cheese in there' - sustainable changes that fit in with you.

Try and gently increase portion sizes, and eat plenty of non refined carbs. Potatoes, oats, brown rice. And add more fruit, dried as well as fresh.
If you don't like eating large portions you can use nutrition supplement drinks, like ensure compact. They give 300cals and are only 125mils. If you keep them in the fridge they're quite pleasant. I've tried others but they don't taste as good and are bulkier. You can use those as a top up if you struggle for time and have quite small stomach capacity.
Snack on nuts, cheese, full fat yogurt, hummus with veg and crackers etc. And if you like sweets or chocolate have a bit more of that too!
It's great to try and be a healthy weight. But it's true a lot of info online is either for weight loss, or weight gain for ED.

YANBU, apart from this bit...

I have daughters and am starting to feel uncomfortable about being so skinny.

It sounds a bit ridiculous that you're uncomfortable about explaining humans come in different shapes and sizes.

Teen dd has been under a dietian for low weight. Things we were advised to try (but were told not to do all at same time).
We were encouraged to swap everything up so full fat milk instead of semi.
Add high calorie foods in eg cream in a hot chocolate, curry or over fruit.
Have three meals and 2 snacks a day.
Get into food routines.
Add an extra tablespoon to a meal (eg usually do half pasta half sauce) as that probably won't overwhelm if it's the same food just a slightly bigger quantity (over 3 meals that's a good few calories).
Dd is slowly putting on weight and is now in a good routine, so seems to be helping.

Oh, and when I say 'good skincare', I do not mean expensive, unnecessary shite. I mean a decent routine, morning and night, every day.

I don’t think this is a silly post at all op. I have quite a few friends in their forties who lost weight and, while not as low as that BMI, it has definitely aged them so I think there is an age at which thinness does promote a slightly more haggard appearance . I would also say I was a similar bmi for many years to you and was advised to nudge it very slightly upwards for pregnancy. I was amazed that in fact I felt far healthier on many fronts when pushing over 20 bmi, so I do think there is definitely a “ sweet spot “ that may differ for different individuals. If I needed to put on weight now I would do it with calcium rich foods for my bones!

I can relate, I am the same. I have no real advice as I have come to accept that this is the way I am made. I am 47 btw and find makeup/good skincare helps the hagginess enormously. Things like hairstyles and necklines, as well as colours can work wonders too.
Have you ever tried focusing on building muscle instead of just gaining weight?

The advice given to people who need to put on weight after illness is as follows. Eat little and often and increase calories by adding fat. So add FF milk, greek yogurt, butter, cheese, cream to your normal diet. Avocado and nuts are also good. If you're consuming more calories then your energy will increase and you'll be able to do muscle building exercise.