Weaning is a stressful period for pigs, and even with optimal conditions some pigs still seem to fail to eat adequately. By understanding the reason behind this behaviour it could be corrected and nursery performance improved. In this study, fasted pigs were observed to have behavioural changes that did not occur in fed pigs. As well, ketone BHBA levels were raised. Once reintroduced to feed, BHBA levels returned to normal. Body condition scoring was ineffective at distinguishing between fasted and eating pigs, but BHBA levels could potentially be used in the future.