This is not a bad thing. Food is so abundant that globally, more people are obese than underweight. This is pretty remarkable considering that for all of human history, up until recently, periods of mass starvation was the norm.
I lost multiple dress sizes while making zero effort to lose weight by working on improving my nutritional status.
Or at least while working on it.
(Insert some XKCD comic about cause and correlation.) ;)
I did a lot of research into what kinds of nutrients I was likely short on.
I started with supplements because they are far easier to deal with. This comment by me might cast a little light on that: https://news.ycombinator.com/item?id=20714419
Some things I found useful:
Celtic sea salt is the single best sea salt. But any sea salt, kosher salt or canning and pickling salt is better than table salt.
If you are on any medication whatsoever, research "nutrient depletions" for that drug. So, for example, if you take Ibuprofen a lot, it depletes a specific B vitamin. This helps you determine specific nutrients you probably need.
Keep a food journal.
Look up super foods. So, for example, when I decided to work on my selenium deficiency, I ate one or more Brazil nuts most days for about six months until I was sick of them and apparently no longer deficient because they are crazy high in selenium.
(Quick and dirty answer. Not to be mistaken for a comprehensive answer.)
What makes Celtic sea salt the best?
Don't get me wrong; I'm thankful that we possess this technology from the perspectives of advancement of knowledge and having more tools to avert food crises. But these technologies were all developed recently enough that while our understanding of the directly attributable outcomes is fairly good, our understanding of long-term and systemic effects on society is anything but complete.