While the Flash has always had the ability to heal quickly, it’s been questionable how his power functions in the DC Universe. However, Wally West’s speed healing was once explained, relating to his metabolism.
It’s been debated several times whether the Flash is the most powerful hero on the Justice League. Between accessing the Speed Force and traveling through time, he can basically rewrite reality. When the DC Universe was rebooted into The New 52, it was a result of Barry Allen running fast enough to reinvent the timeline. The Flash also has a wide array of smaller abilities which are frequently forgotten. Even his lesser powers from the Speed Force can have major ramifications. Flash's ability to heal himself was explored in Flash Vol. 2 #131, written by Mark Millar and Grant Morrison with art by Paul Ryan, inks by John Nyberg, and colors by Tom McCraw.
After shattering his legs during a running accident in Flash Vol. 2 #130, Wally has to take a rest day. While in a wheelchair, he is joined by Jay Garrick, Max Mercury, Impulse, and Linda Park. During their time together, Max speaks to Wally’s healing ability, saying that the Flash’s metabolism moves at super-speed and allowing any injuries to heal at the same rate that he digests food. Max comments, "Your super-speed metabolism could have you healed and walking again with a week or two..." Flash fans have known that Barry and Wally both require an enormous amount of carbs to burn off calories while running. Otherwise, the Flash would meet his demise. The Flash’s required consumption of food goes hand in hand with his sped-up healing ability.
Theoretically, Wally should be able to heal at the same rate that he runs. Since his speed has been contrasted with Barry through the years, it seems that the faster speedster would also heal more quickly. Throughout the series, his speed is referred to as “light speed,” inferring that he is at his prime as a speedster. In the issue, Wally wears a suit powered by the Speed Force which seemingly helps the process of healing to go even quicker. A few issues later in Flash Vol. 2 #134, Jay steps in for Wally as the Flash during the second week of his injury.
As the Flash has commonly employed actual scientific knowledge to use his powers, writers have considered how his powers might work in the real world. It has been recorded that major injuries like the one that Wally had could take up to a year for someone to heal, and regain the ability to walk. While considering the use of the Speed Force suit, Flash's recovery time was compiled into a two week period from the average person’s year-long stretch.