This is not quite true. Twinkies were mentioned, (though it was a just a small part of the diminished capacity defense. The following quote is from:
Eileen A. Scallen & William E. Wiethoff, The Ethos of Expert Witnesses: Confusing the Admissibility, Sufficiency and Credibility of Expert Testimony, 49 Hastings L.J. 1143, 1161-66 (1998):
"At the trial, White presented a defense of diminished capacity, using [precedent] . . . which held that evidence of diminished capacity, whether from intoxication, trauma or mental disease, could be used to show that the defendant did not have a specific mental state such as malice aforethought, or could not premeditate or deliberate to the degree required for a conviction of first degree murder. Thus, White presented expert testimony regarding his mental state at the time of the killings. This expert testimony was the source of one of the trial's most memorable images and one of the most reviled examples of "junk science" - the "Twinkie defense," as the press referred to the testimony of Dr. Martin Blinder. This defense expert testified that when White became depressed, he ate large amounts of junk food - Twinkies, Coca-Cola, etc. Moreover, Dr. Blinder testified that when "susceptible individuals" like White consume "large quantities of what we call junk food, high sugar content food with lots of preservatives can precipitate anti-social and even violent behavior." However, what is now forgotten is that the defense did not rely solely on the "Twinkie" theory; four other psychiatrists also testified for the defense, uniformly agreeing that White suffered from depression to such a degree that he possessed diminished capacity at the time of the killing and could not premeditate or deliberate."
