Malnutrition may be a contributing factor to obesity. We crave more food when we’re not getting what we need. If it’s not there to begin with, or at best a lesser amount, then ever more never satisfies.
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.)