Submitted to: International Journal of Obesity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/4/2008
Publication Date: 9/30/2008
Citation: Burton-Freeman, B., Keim, N.L. 2008. GLYCEMIC INDEX, CHOLECYSTOKININ, SATIETY AND DISINHIBITION: IS THERE AN UNAPPRECIATED PARADOX FOR OVERWEIGHT WOMEN? International Journal of Obesity. 32:1647-1654. Interpretive Summary: Carbohydrate-rich foods that rapidly increase blood sugar have a high glycemic index whereas foods with carbohydrates that have a slower effect on blood sugar have a low glycemic index. It has been assumed that low glycemic index diets will reduce hunger and increase fullness because generally, they are high in fiber and volume and are digested more slowly. However, there is little scientific evidence available to support this assumption. We conducted a controlled feeding trial in overweight women to compare high-carbohydrate meals with high or low glycemic index on feelings of hunger and fullness and response of two prominent hormones known to regulate digestion, absorption, and appetite: insulin and cholecystokinin (CCK). Contrary to what we expected, with the high glycemic index meal, feelings of hunger were less and blood levels of insulin and CCK were higher compared to the low glycemic index meal. Upon closer examination of our data we found that the women whose eating behavior could be described as “restrained” with a high tendency “to lose control of the restraint” had low CCK responses to both meal types. With a low CCK response, hunger will not be fully suppressed after eating a meal. This study suggests that it is important to consider eating behavior traits when interpreting physiological response to meals.
Technical Abstract: The clinical utility of a low glycemic index (GI) diet for appetite and food intake control is controversial. Complicating the issue is psychological and behavioral influences related to eating. The aim of the present study was to investigate the satiety and glycemic response to high and low GI meals in overweight restrained (R, n=12) and unrestrained (UR, n=10) women. In a randomized crossover study, subjective satiety, cholecystokinin (CCK), glucose, insulin, and triacylglyceride (TG) were measured at defined intervals for 8 h after subjects consumed high GI (HGI) or low GI (LGI) test meals. Test meals were matched for energy, energy-density, macronutrient content, and available carbohydrate, but differed by carbohydrate source; refined grain vs. whole grain, respectively. The HGI meal resulted in greater satiety overall, suppressing hunger, desire to eat and prospective consumption compared to the LGI (p<0.01) meal. Plasma glucose, insulin and TG were also higher after the HGI meal compared to LGI meal (p<0.0001). Dietary restraint did not significantly influence CCK (p=0.14) or subjective satiety (p>0.4); however, an interaction of restraint and disinhibition on CCK was apparent. CCK was blunted in R subjects with higher disinhibition scores than UR or R subjects with lower disinhibition scores (p<0.05). We conclude that a low GI diet may not be suitable for optimal satiety and appetite control in overweight women. The relationship between cognitive influences of eating and biobehaviorial outcomes requires further investigation.