Nicknamed “Chunky”, DeGale has previously adopted a more relaxed attitude to eating, arbitrarily tapering off his intake as the weigh-in for big fights approached.
And that remained his strategy even when he became IBF world super-middleweight champion in 2015 and for his first two defences.
However, DeGale brought in Nick Palmer, a strength and nutrition expert, ahead of his unification bout against Badou Jack.
The 31-year-old had faded in the latter stages against Rogelio Medina and was dropped late by Jack, but escaped with a draw and his title intact.
But Palmer has come to understand DeGale’s body even better over the last 11 months and believes they are streets ahead of where they were last year.
“Whenever you’re an athlete and you’re exercising a lot, you can always get away with eating pretty much what you want,” Palmer told Express Sport.
“But we had to sit down with him and look at what he was eating, how much and we found we had to clean it up.
“We had to make it more calculated in terms of the calories he was eating, the quantities and the sensible tapering strategies to get you to the weight.”
Palmer is confident DeGale will weigh in on Friday inside the 168lb super-middleweight limit.
In fact, the pair have refined their nutrition strategy after coming in more than a pound-and-a-half under the limit in January.
“Actually, we found that because he was eating high-calorie food but in lesser volumes, for the last fight we were actually feeding him a lot more low-calorie, high-density food,” Palmer added.
“For pre-Badou Jack, I gave him three meals which is something we’ve never done before. We weighed him the hotel the night before, him and Jim knew where his weight needed to be and he was below it.
“I said to him ‘you may as well have a meal’. It wasn’t a big meal but it was something.
“It was a bit strange because he said ‘if I eat that, am I going to be over?’. I said ‘it’s impossible’.
“It meant that he was able to get in the ring with a bit more fuel in his system and feeling a bit better psychologically.”