[groan] Don't bother.
Malnutrition IS associated with obesity. So the first suggestion that people hear is "take a multivitamin/mineral." Unless your diet is 100% GARBAGE (and some people do have such a diet) it's not going to fix much.
What are the worst imbalances in the common diet? Maybe, lack of pantothenic acid? Hardly (by dictionary definition, it's everywhere). My vote is for TOO MUCH omega-6 fats, TOO MUCH fructose, TOO MUCH insulin-stimulating foods of all kinds, TOO LITTLE protein, TOO LITTLE omega-3s, short- and medium chain fatty acids.... No vitamin in the world is going to balance these problems.
Then, what good is it going to do you to take calcium, if your low K2 just sends it into your circulatory system instead of your bones and teeth, where it'll actually do you some good? What good, all the minerals in minuscule quantities, which compete with each other for absorption? What good vitamin C, when all the sugar in your diet ties up the receptors?
Thanks to SOME researchers, who have determined how nutrients perform in the body (NOT in vitro, which tends to mean about as much as epidemiological studies do), we can approach the subject of supplementation intelligently. Read up on anything you have doubts about, from a reputable source -- people get themselves into trouble supplementing single substances when they don't. Heard the stories about Hashi's patients getting sick on iodine? That's because somebody didn't do their homework, and make sure they were sufficient in selenium too....
I don't think that there's much doubt, nutrients are BEST acquired through whole foods ... UNLESS there are absorption issues. Nature, which formed us, also put our ideal food together -- though not in that order -- and the way nutrients arrive through a pre-agricultural diet require less adaptation by us to assimilate. Less STRESS to our bodies (don't we have enough stress with modern lifestyles?).
But the next time your body doesn't act quite right, it's only reasonable to ask yourself, "could i be deficient in something" rather than "can i get a prescription to fix this."