Norra MacReady

October 25, 2010

October 25, 2010 (San Diego, California) — A preference for late dinners might increase your risk for obesity, according to a small study presented here at Obesity 2010: The Obesity Society 28th Annual Scientific Meeting.

Rika Yokoyama, MS, and colleagues from the Health Care Food Research Laboratories of the Kao Corporation in Tokyo, Japan, compared the effects of early and late meals in a crossover study of 10 healthy Japanese men. The men consumed lunch at 1:00 pm and breakfast the following day at 8:00 am; they had dinner at 7:00 pm in the early dinner (ED) condition and at 10:00 pm in the late dinner (LD) condition. All meals were the same, and were consumed in a respiratory chamber, where the subjects' energy expenditure and fuel utilization were measured from 12:30 pm until 11:30 am the next day.

Blood metabolite levels were measured 1 hour after every meal, and the men rated their appetite hourly on a visual analogue scale (VAS), which ranged from 0 (not hungry at all) to 100 (as hungry as I've ever felt). The men had an average age of 40.4 (±6.9) years and an average body mass index of 23.1 (±2.2) kg/m2.

In the ED condition, average 23-hour energy expenditure was 1885 (±231) calories; in the LD condition it was 1837 (±228) calories (P < .05).

"We saw a sharp decline in postprandial energy expenditure, or diet-induced thermogenesis (DIT), during sleep after the LD condition. In the ED condition, the decline was more moderate," Ms. Yokoyama told Medscape Medical News. "Presumably, that was because in the ED condition, more time elapsed between dinner and bedtime. However, we could not identify the reason the DIT declined so sharply during sleep after the late dinner." Nor could the differences be traced to variations in physical activity; infrared motion sensors in the respiratory chamber did not detect any changes in physical activity between the conditions," she explained.

Insulin and blood glucose levels were markedly higher in the LD than in the ED condition after dinner (P < .01). Free fatty acids were also higher in the LD condition, and remained elevated until breakfast the following day. The authors concluded that eating dinner late was associated with lower total energy expenditure, hyperinsulinemia, and hyperglycemia, which over time could result in obesity.

Appetite scores on the VAS also were significantly higher just before dinner in the LD than in the ED condition (P < .05).

"This small study is provocative and may serve to suggest hypotheses that could and should be tested in larger studies before generalizable conclusions can be drawn," said Howard Eisenson, MD, associate professor of community and family medicine, and executive director of the Duke Diet and Fitness Center at Duke University School of Medicine in Durham, North Carolina.

Still, he said, "I believe that those specializing in the treatment of obesity will not be surprised that, at least in this small and very short-term study, a late night dinner seems to be associated with unfavorable changes in terms of weight management and risk for diabetes: increased appetite, decreased energy expenditure, and increased insulin and blood sugar levels. The implications for clinical practice are not yet clear, but this preliminary study should trigger broader research and may ultimately provide good evidence to support a personal and public health message."

Ms. Yokoyama and Dr. Eisenson have disclosed no relevant financial relationships.

Obesity 2010: The Obesity Society 28th Annual Scientific Meeting. Poster 202-P. Presented October 12, 2010.

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