Wheat germ is normally incorporated in diet programs for it's natural nutritional value - protein, Vitamin E and some B-Complex vitamins. That's why I add some to my homemade wheat bread each week when I'm baking bread.
While B-Complex vitamins can stimulate appetite - wheat germ isn't on any of the lists that I have found. In Prescription for Nutritional Healing they list things that are B-Complex appetite stimulants - ginger, catnip, fennel seeds, gensing, gotocola, etc. ... but wheat germ is not listed. Perhaps the best appetite stimulant listed is brewer's yeast - well, behind cannabis but that's not legal in the US and many parts of the world.
I can only assume that if you sprinkle some wheat germ on your yogurt, or ice cream, it will not send you into an uncontrollable feeding frenzy - or even stimulate you to go seeking a second helping (it never has in my case). It could, however, contribute to better health over time - and that could in turn lead to a better appetite.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain