Scientists from Johns Hopkins University found that eating a late dinner could harm metabolic health and may increase the risk of obesity.
Consuming calories later in the day is linked to obesity and metabolic syndrome.
Recent research has found eating dinner later in the evening could cause weight gain, as well as increased risk for heart disease, stroke, and diabetes.
This can happen because meal timing may have negative effects on your metabolism.
In the study, researchers hypothesized that eating a late dinner alters metabolism during sleep in a manner that promotes obesity.
They aimed to examine the impact of late dinner on metabolism at night in healthy people.
The team tested 20 healthy young volunteers (10 male, 10 female). These people had a fixed sleep period (23:00-07:00) in a laboratory setting.
Each participant ate a late dinner around 22:00 in half of the experiment period and a routine dinner (18:00) in the other half of the time.
The dinner included 35% daily kcal, 50% carbohydrate, and 35% fat.
The researchers tested the night and next-morning blood sugar, insulin, triglycerides, free fatty acids (FFAs, a source of body energy), cortisol (stress hormone), dietary fatty acid oxidation, and sleep quality.
They found that later dinner caused a 4-hour shift in the postprandial period, overlapping with the sleep phase.
The postprandial state, broadly defined as “the period following a meal,” is a complicated physiological process that is responsible for the metabolism of nutrients and the supply of tissues with essential metabolic fuels.
The team found that independent of this shift, participants eating a late dinner showed higher blood sugar (18% higher), and the amount of fat burned overnight decreased by about 10% compared to eating an earlier dinner.
Late dinner did not affect sleep, but it increased stress hormones in the blood. These metabolic changes were strongest in people who were early sleepers.
The researchers concluded that late dinner could lead to blood sugar intolerance at night, and it reduces fatty acid oxidation and mobilization, particularly in earlier sleepers.
These effects might lead to obesity if they happen every day for a long time.
Although this study is not the first one showing the harmful effect of late dinner, it is one of the most detailed.
One limitation of the study is that whether the harmful effect will continue over time is still unknown.
In addition, whether changing people’s behavior (sleeping soon after dinner) could reduce the harm needs more work to find out.
The research is published in The Journal of Clinical Endocrinology and Metabolism and was conducted by Chenjuan et al.
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