There have been other studies on this subject that suggested that late dinners are not the healthiest thing. But this is the first study to do an extremely detailed and controlled experiment. The researchers studied 10 healthy women and 10 healthy men in a laboratory setting. These participants wore activity trackers, had blood sampling every hour while staying in the lab, underwent sleep studies and body fat scans, and ate food that contained non-radioactive labels so that the rate of fat burning could be determined.
High blood sugar and less fat burning
The main question was how would the 20 subjects metabolize a dinner eaten at 22:00 compared to 18:00 hours. The volunteers all went to bed at 23:00. The researchers found that blood sugar levels were higher, and the amount of ingested fat burned was lower with the later dinner, even when the same meal was provided at the two different times.
“On average, the peak glucose level after late dinner was about 18% higher, and the amount of fat burned overnight decreased by about 10% compared to eating an earlier dinner. The effects we have seen in healthy volunteers might be more pronounced in people with obesity or diabetes who already have a compromised metabolism,” said the study’s first author Chenjuan Gu, M.D., Ph.D., of the Johns Hopkins University.
It depends on when you go to bed
The authors concluded that a late dinner causes nocturnal glucose intolerance particularly in early sleepers and that it might promote obesity if they recur chronically. They also remarked that the timing is individual and depends on the person’s habitual bedtime.
“This study sheds new light on how eating a late dinner worsens glucose tolerance and reduces the amount of fat burned. The effect of late eating varies greatly between people and depends on their usual bedtime. This shows that some people might be more vulnerable to late eating than others. If the metabolic effects we observed with a single meal keep occurring chronically, then late eating could lead to consequences such as diabetes or obesity,” said the study’s corresponding author Jonathan C. Jun, M.D., of the Johns Hopkins University.
If you’re having dinner close to your bedtime then you just got a great weight loss tool! Try to eat earlier, maybe about 3 hours before going to bed, and your fat burning and glucose control should be better.