A recently published study has found that exercising before breakfast aids metabolism and may be more effective than exercising after breakfast. The study, which was published in British Journal of Nutrition, tested 10 men who would be classified as overweight and aimed to consider the participants metabolism.
Essentially, the participants had to take part in three different conditions in a laboratory and be observed for 8.5 hours in total. Each condition was completed two weeks apart and the findings from each condition were compared. In the first condition, the men had to do exercise before having breakfast and were then given blood tests at regular intervals during the observation period. The tests were used to measure the participants’ fat and carbohydrate breakdown as well as the overall energy expenditure. In the second condition the men had to perform exercise after breakfast and were given the same blood tests. Lastly, in the third condition, the men did not perform any exercise but were again given the same blood tests. In addition to a standardised breakfast, participants were also given access to a buffet lunch and told to eat until they felt full. However, unbeknownst to them, the researchers weighed the food before and after in order to calculate how much food had been consumed and what type of food was consumed. The reason for omitting to mention this information to participants before the end of the study was that the researchers were keen to avoid influencing participants’ behaviour in terms of the amount and type of food they chose to consume.
As might be expected, the researchers noted that the exercise conditions provided the largest fat and carbohydrate breakdown and the highest energy expenditure. However, the key finding worthy of further investigation was that the overall energy expenditure was higher, and the breakdown of fat relative to the breakdown of carbohydrates was greater, when men exercised in the morning. As the glycogen levels would be low, this could provide a scientific explanation for the findings. The findings also bear resemblance to previous findings reported in Canada and France.
As the conditions were performed only once, the findings cannot be considered reliable and may be due to chance. Therefore, this would need to be replicated in a larger sample and during a longer period of time before any conclusions can be made. However, this and many of the limitations of both the methodology and the applicability of the current study were acknowledged by the researchers. We agree with the researchers and feel that although the findings cannot be interpreted as definite evidence, the study itself considers an interesting idea and brings instrumental value in guiding future research.