Ordered Eating and Its Effects on Various Postprandial Health Markers: A Systematic Review

Aberrations in glucose, insulin, and other postprandial (PP) markers are common in obesity and cardiometabolic disorders. One potentially simple lifestyle/dietary modification to manage these issues is to change the order in which foods are consumed within meals. Carbohydrate exerts the largest effect on PP glucose, and there is some evidence that ingesting dietary fat or protein before carbohydrate delays gastric emptying of carbohydrate and reduces PP glucose. Additionally, certain dietary proteins may augment insulin release if ingested with carbohydrate, thereby improving blood glucose clearance. This review aimed to systematically evaluate evidence from acute experiments that modified the order in which foods were consumed in isocaloric meals.

Outcomes of interest were PP glucose and insulin (including area under the curve for both), C-peptide, gut hormones, and perceptual responses. Three databases were searched (PubMed, Cochrane CENTRAL, Web of Science) in February 2022. Additionally, reference lists of identified reports were searched, and an author of several studies was consulted to verify that relevant literature was included. The review included acute interventions that administered isocaloric meals of the same foods but with foods eaten in different orders. Studies were not excluded based on participant characteristics.

Eleven reports were identified. All reports that assessed glucose and insulin showed a tendency toward lower levels, at least over parts of the PP period, by consuming carbohydrates last. GLP-1 tended to be higher in carbohydrate-last conditions, though this was only measured in a few studies. Perceptual responses (hunger, fullness, etc.) were not consistently different between conditions in two studies, but the certainty of evidence was very low.

Findings indicate that, at least acutely, there may be benefits to eating carbohydrate after vegetable and/or protein-rich foods. The most consistent effect (judged as moderate certainty) is that carbohydrate-last meal orders tend to lower blood glucose and insulin excursions.