Researchers at the University of Northumbria at Newcastle did not have a large study group
, and it did not include females, but the results were consistent with the 12 physically fit males they had. Some did not eat upon awakening, others had a normal breakfast 90 minutes prior to their workout. At 10 a.m. each morning they got on a treadmill
and had a run.
After their run they were given chocolate milk for recovery and not long after that a pasta lunch was served and each was told to eat until they'd had enough. The researchers found that all the participants ate about the same and that those who had fasted did not consume more food to compensate for not having had a breakfast before working out.
Exercising to maximize weight loss
Researchers said not having breakfast meant the fat expended while working came from existing fat. “In order to lose body fat we need to use more fat than we consume," Javier Gonzalez, one of two lead researchers, said in a press release. "Exercise increases the total amount of energy we expend and a greater proportion of this energy comes from existing fat if the exercise is performed after an overnight fast.”
The other lead researcher in the study, Dr. Emma Stevenson, said that their results were “very important in helping to provide practical guidelines relating to food intake to individuals who are exercising to maximize fat mass loss."