One way to keep going out there is to switch from the traditional heavy carbohydrate diet to a more protein and fat rich diet, but you may get "carbo flu" for a while as your body is used to using glucose for energy. You could read some of this dude's stuff:
http://www.gnolls.org/index/
or here:
http://eatingacademy.com/
But, be warned, this is fringe stuff that you'll never hear from a dietician and most people are keen to dismiss as a fad.
If you eat a proper diet, you really shouldn't need all kinds of costly supplements but you might have to be a bit flexible in your thinking. With the exception of some electrolyte replacement due to excessive sweating that happens in the tropics.

Just out of curiosity, what is it you are actually doing for work?

Good luck with it anyway. There is lots of conflicting advice out there, all of which sounds good and backs itself up with "science" and it's pretty hard to sort through, on a true scientific basis, what really is the optimal human diet. You could do the n of 1 experiment, where you change your diet around with little tweaks and see what works for you. The only caveat is that you sometimes have to go through a rough period before you begin to feel better on any new dietary change.

I think one thing the research conclusively shows, and even the high carbo/low fat junkies will agree is that protein is the most filling food to eat. But, again it's tough to get adequate amounts of protein on a vegetarian diet. If you are eating mostly carbos you really are going to have to expect blood sugar spikes and troughs from the insulin response and that makes a person hungry.