In a new study, Harvard Scientists put this down to our circadian rhythms, which control the body’s internal clock.
For 37 days, participants lived in a laboratory without windows, phones and access to time or Internet to eliminate any environmental disruptions. Their sleep and wake cycles were then disrupted by four hours each day, forcing their circadian rhythms to operate only on internal factors. In addition, they each wore a sensor so the researchers could observe what effect this had over their energy expenditure. (FYI, the higher the core temperature, the more calories that person is burning.)
Interestingly, they found that the participants’ body temperatures were lowest in the early morning and late at night and then spiked (by about 10 per cent) in the late afternoon. This equates to about 130 extra calories burned while at rest.
The researchers say this increase (albeit small) could have a huge impact on our health.
“Let’s say we get up an hour or two hours early and eat breakfast an hour or two hours early,” explained Dr Jeanne Duffy, the study’s co-author and a neuroscientist at Harvard Medical School. “We may be eating that breakfast not only at a time when our body might not be prepared to deal with it, but also at a time when we need less energy to main our functions. Therefore, the same breakfast might result in extra stored calories, because we don’t need those to maintain our body functions.”
Still, Duffy advises that more research is required before she recommends that people reschedule their workout and meal times around this late-arvo energy surge.