New research has shown that cancer patients recover more quickly when given liquid food immediately after surgery.
In a study of 121 people with cancer of the stomach, pancreas and oesophagus, patients recovered three days more quickly if given food straight away to their intestine rather than fasting for 10 days, as is normally the case.
The scientists, from Cardiff University and the University Hospital of Wales, also found that patients were less likely to suffer complications later on, such as wound and chest infections.
The process could save the NHS millions of pounds a year, according to the study funded by the Health Foundation.
Lead investigator Dr Rachael Barlow, from Cardiff University, said: "In our trial we turned the traditional thinking to starve patients after major gastrointestinal surgery on its head and have found huge benefits.
"The striking find that nutrients straight after surgery meant patients recovered quicker and tended to have fewer complications has major implications for the NHS.
"Importantly, patients who were given the nutrition were more likely to be healthier and have a better quality of life in the months after surgery."
Patients would usually fast and receive fluids through a drip.