Death row inmates who continue to protest their innocence are less likely to choose last meals before being executed, a scientific study has shown.

After studying the last meals of 247 people executed in the United States between 2002 and 2006, Kevin M Kniffin of Cornell University found that those who admitted guilt were also more likely to order a high-calorie meal as their final repast.

"People who denied guilt were 2.7 times as likely to decline a last meal than people who admitted guilt (29% versus 8%)," writes Kniffin.

"People who admitted guilt requested 34% more calories of food than the rest of the sample (2,786 versus 2,085 calories)."

The study quotes prisoner Elias Syriani, who strenuously denied murdering his wife, and declared: "I want no meal from this place", immediately before his execution in 2005.

Philip Workman, executed for murdering a Tennesse police officer, also strongly denied his guilt, and when asked what he wanted for his final meal told officials to deliver a pizza to a homeless person instead.

Kniffin reasons that accepting a final meal could be regarded as condoning the execution process, so those who deny guilt would be more likely to reject it.

"To the extent that agreement to accept the traditional invitation of a last meal implies some consent to the execution process, it is sensible that people who deny guilt will tend to deny the invitation to a last meal," Kniffin writes.

"People who are facing an execution for which they claim innocence appear to lack an appetite when compared with the rest of the sample whereas people who have accepted guilt appear relatively more 'comfortable.'"

A jailhouse video by North Carolina killer Marion Pruett is also discussed, in which he describes an "extravagant high-calorie final meal" he will enjoy and explains that he has "made his peace."

"Just as warning labels on tobacco products appear to ironically increase tobacco consumption for some people, our study of last meals suggests that drawing attention to death has the potential to invite overconsumption of food for some people while, notably, approximately 20% of the people opted to eat nothing," Kniffin argues.

Texas abolished the last meal in 2011, after condemned prisoner Lawrence Russell Brewer requested chicken-fried steaks with gravy and sliced onions, a triple-patty bacon cheeseburger, a bowl of fried okra with ketchup, a pound of barbecued meat with half a loaf of white bread, three fajitas, a meat-lover's pizza, ice cream, peanut-butter fudge with crushed peanuts and three root beers.

He then said he wasn't hungry and sent the food back.