Many of us have heard the saying that we should eat breakfast like a king, lunch like a prince, and dinner like a pauper. And yet in Asia, the reverse is often observed—it is culturally common to consume large, carbohydrate-rich meals late in the evening.
Consuming meals that rapidly increase blood glucose—high glycemic index (GI) food—may pose a problem for Asian populations, given their unique metabolic phenotype which predisposes them to develop type 2 diabetes and prediabetes, compared to Caucasian populations.
Researchers have long suspected that the timing of when we eat can interact heavily with carbohydrate metabolism. This is an emerging field of nutritional science known as chrononutrition, which aims to develop an understanding of how when we eat may impact our health.
“It is now well recognized that almost 70 percent of all chronic disease etiology can be ascribed to the diets we consume,” said study corresponding author Christiani Jeyakumar Henry, Senior Advisor, of A*STAR’s Singapore Institute of Food and Biotechnology innovation (SIFBI) and Director, of A*STAR’s Clinical Nutrition Research Centre (CNRC). “This puts food at the center stage of public health. But how about the timing of when we eat them?”
To investigate the chronobiological impact of carbohydrate intake, Henry and colleagues conducted a randomized controlled trial on 34 healthy Chinese volunteers by giving them either high or low GI meals for breakfast and dinner. The low GI meal used special low GI rice instead of regular white rice.
After each meal, the researchers monitored various markers of glucose homeostasis in the blood, including glucose, insulin and triglyceride levels. Their findings showed that a high GI meal taken at dinner results in poor glucose regulation as compared with the same meal taken at breakfast.
“It came as a surprise to find that the dinner meal had a much more detrimental effect on blood glucose compared to a similar meal at breakfast,” said Henry. Moreover, the effect was still observable at the subsequent meal, suggesting that glucose clearance is much slower in the evening than in the morning.
Based on these results and the findings of previous studies, Henry recommends having a low GI breakfast and avoiding carbohydrate-rich dinners late in the evening. However, he acknowledges that the preference in many Asian cultures for having a large, substantial meal at dinner time is not going to change overnight.
“The timing of your meal may have serious health implications,” Henry said. “Yet, changing food habits is not easy, as it is bound by values, culture, habits and rituals.”
Henry’s team is currently in touch with the Singapore Food Agency and the Health Promotion Board to share their findings with the general public. They recommend that future epidemiological studies investigating the GI of diet and disease risk associations should also factor in the timing of carbohydrate intake.
The A*STAR-affiliated researchers contributing to this research are from the Clinical Nutrition Research Centre (CNRC), Singapore Institute of Food and Biotechnology innovation (SIFBI) and Singapore Institute for Clinical Sciences (SICS).