good books on nutrition and how it all works

Most of it is "nutribollocks".

Read "Food Isn't Medicine". That's all you need.

I can summarise it for you here though:

Eat a varied diet, mostly plant based and wholegrain, avoid too much saturated fat and sugar, limit processed food.

My employer provides weight management and healthy eating advice on behalf of the NHS & local authorities.

I work on a lot of the content supporting the service, and it largely reflects what Kramer said.

You can probably find everything you need here: https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/the-eatwell-guide/

'More Fuel You' by Renee McGregor is a good one: https://www.adventurebooks.com/products/more-fuel-you

I hear the Tim Spector books might be good – anything else to consider?

I think Spector's stuff is decent enough. Mostly though it's eat a variety of vegetables, fruit, cook from raw basic ingredients, with spices etc, wholemeal pasta and bread a good idea, try not to snack on biscuits, cake etc and stay away from the sort of ultra-processed salty, fatty, sugary food that seems to be the staple of the typical modern UK diet.

On the latter, the podcast series that the van Tulleken doctor twins on UPF is worth a listen and available on BBC Sounds, quite sobering but also entertaining. Even that's not particularly complicated though, mostly if something contains ingredients that you wouldn't have in your own kitchen / don't recognise as food, you should probably avoid. Supermarket ingredient lists are terrifying, even the simplest things seem to contain all manner of weirdness that you'd never include if you were making the same thing at home.

I found this a good book, More Fuel You..

https://amzn.eu/d/iqETisJ

The Zoe podcast can be an interesting listen, and not much more to be had by paying for book, but it basically states it isn't rocket science, eat well balanced, freshly prepared from real ingredients and eliminate processed foods etc.

I’ve been looking at improving my diet this last year for a couple of health issues,

Speak to your GP about getting a referral to a dietician.

"Nutrition" books are mostly sold by people who have a book to sell.

Patrick Holford has been an education for me. Interesting reading.

The complete guide to sports nutrition by Anita Bean is a go to for accessible science based reading.

Contrary to above it is possible to get factual objective books on topics such as nutrition that are not selling things, pushing an agenda or some wild food-based ideology.

I believe most books are written by people who have a book to sell.

I hear the Tim Spector books might be good

Yes they are - and well pretty much tell you what Kramer said.

PS some of his podcasts are very good, try this one:

https://open.spotify.com/episode/1uudRtDoRGEDrTsi19Ynvn?si=Y_CG7JXbR2q5AeEMDO2jFg&context=spotify%3Ashow%3A1xDawqT8Cgm6HAnbpFX5T5