Really? Anahad O’Connor tackles health myths.

Loading up on carbohydrates before running a race is a well-established practice. But carbo-loading before surgery?

To many people, it might sound counterintuitive. Hospitals traditionally ask patients to avoid solid food for a minimum of six hours before surgery, and liquids for at least two hours. The primary reason is to prevent vomiting while the patient is under anesthesia.

But studies have found that after surgery, the body is in a stressed metabolic state, prompting it to dip into stores of fat, carbohydrates and protein for fuel and to repair tissue. Being in a depleted state as the body is trying to heal, some researchers have found, may prolong recovery and raise the risk of complications.

So what happens if, just before the two-hour period without liquids, the patient stocks up on carbs? In one study conducted by surgeons in England, 36 patients about to undergo colorectal surgery were randomly assigned to one of three regimens. Some went on the traditional fast. Others were given water, as a control. And the rest were told to drink a solution containing a starch derivative called maltodextrin.

After surgery, the patients in the carb group needed shorter stays in the hospital, roughly 7.5 days on average, compared with those in the fasting group, who required about 10 days. Carbo-loading patients also had a quicker return of normal gut function after surgery and had smaller reductions in muscle strength. Other studies have shown similar results for recovery and have also found that having a drink containing carbohydrates up to two hours before surgery appears safe.

THE BOTTOM LINE Liquid carbohydrates up to two hours before surgery may aid recovery, but more research is needed.