The Individual and Combined Effects of Glycemic Index and Protein on Glycemic Response, Hunger, and Energy Intake

Abstract

Although high protein and low glycemic index (GI) foods are thought to promote satiety, little is known about the effects of GI, protein, and their interaction on hunger and energy intake several hours following a mixed meal. This study investigated the long term effects of GI, protein, and their combined effects on glucose, insulin, hunger, and energy intake in healthy, sedentary, overweight, and obese adults (BMI of 30.9 ± 3.7 kg/m 2 ). Sixteen individuals participated separately in four testing sessions after an overnight fast. The majority (75%) were non-Hispanic Blacks. Each consumed one of four breakfast meals (high GI/low protein, high GI/high protein, low GI/low protein, low GI/high protein) in random order. Visual analog scales (VAS) and blood samples were taken at baseline, 15 min, and at 30 min intervals over 4 h following the meal. After 4 h, participants were given the opportunity to consume food ad libitum from a buffet style lunch. Meals containing low GI foods produced a smaller glucose (P < 0.002) and insulin (P = 0.0001) response than meals containing high GI foods. No main effects for protein or interactions between GI and protein were observed in glucose or insulin responses, respectively. The four meals had no differential effect on observed energy intake or self-reported hunger, satiety, and prospective energy intake. Low GI meals produced the smallest postprandial increases in glucose and insulin. There were no effects for GI, protein, or their interaction on appetite or energy intake 4 h after breakfast.

The effect of breakfast type and frequency of consumption on glycemic response in overweight/obese late adolescent girls

“…[17][18][19][20][21][22] However, glucose and insulin responses were not assessed at the subsequent meal in any of these studies. Thus, the current study was the first to examine whether this response would extend into and contribute to the 'second meal phenomenon'.…”

“…Twenty-five (25) H-BS and thirty-one (31) H-BC met the screening criteria, were available for the 8-h testing days, and began the study. Twenty (20) H-BS and fifteen (15) H-BC completed all study procedures. Both groups included overweight, late adolescent girls that showed normal fasting glucose and insulin concentrations ( Table 1).…”

“…6,7 Increased dietary protein has also been proposed to reduce postprandial glucose concentrations, as protein consumption is known to stimulate insulin secretion. 8,9 However, the data is inconclusive with some, [10][11][12][13][14][15][16] but not all studies, [17][18][19][20][21][22] reporting blunted postprandial glucose and insulin responses following the consumption of higher-protein (HP) vs normalprotein (NP) breakfast meals. These conflicting findings may be due to several key dietary factors including, but not limited to protein type (animal vs plant) or food form (beverages vs solids), which varied within and across studies.…”

Effects of Higher Dietary Protein and Fiber Intakes at Breakfast on Postprandial Glucose, Insulin, and 24-h Interstitial Glucose in Overweight Adults

“…Of note, the difference in carbohydrate content of those breakfasts may explain the glucose results as opposed to the combined effect of protein and fiber. In contrast, one previous study [58] systematically assessed the individual and combined effects of low vs. high glycemic index (GI) and protein breakfast treatments on postprandial insulin and glucose responses. Makris et al [58] found that combining higher amounts of protein and low GI simultaneously did not have an effect on postprandial insulin and glucose responses.…”

“…In contrast, one previous study [58] systematically assessed the individual and combined effects of low vs. high glycemic index (GI) and protein breakfast treatments on postprandial insulin and glucose responses. Makris et al [58] found that combining higher amounts of protein and low GI simultaneously did not have an effect on postprandial insulin and glucose responses. However, intake of higher amounts of the low GI breakfast meal attenuated postprandial insulin and glucose responses.…”