Effect of short-term starvation on gastric emptying in humans: relationship to oral glucose tolerance

Abstract

To evaluate the effects of short-term starvation on gastric emptying in normal and obese subjects, the relationship between gastric emptying and oral glucose tolerance, and the mechanisms responsible for the delay in the systemic appearance of oral glucose observed after short-term fasting, we determined the effects of a 4-day fast on 1) gastric emptying and oral glucose tolerance in normal subjects and 2) gastric emptying in obese patients. Gastric emptying of 75 g glucose (320 ml) labeled with 99mTc colloid was measured in 12 healthy volunteers and 11 obese subjects after 12-h and 4-day fasts. In seven other obese subjects, the effect of a 4-day fast on gastric emptying of 320 ml normal saline was quantified. Gastric emptying of glucose was slower after the 4-day than after the overnight fast in both normal (P = 0.02) and obese (P < 0.001) subjects, with no difference between the two groups. In normal subjects, the rate of gastric emptying was related directly to the rise in plasma glucose at 30 min (r = 0.60; P < 0.05) but inversely to the plasma glucose at 180 min (r = -0.64; P < 0.02). In the obese subjects, gastric emptying of saline was not affected by fasting. These observations indicate that 1) gastric emptying of glucose is retarded by a 4-day fast, 2) the changes in gastric emptying reported in obesity may reflect different patterns of prior nutrient intake, and 3) delay in gastric emptying accounts for the slower systemic appearance of glucose after fasting.

Gastric emptying, mouth-to-cecum transit, and glycemic, insulin, incretin, and energy intake responses to a mixed-nutrient liquid in lean, overweight, and obese males

“…For example, the effects of fat on gastric emptying and oro-cecal transit are attenuated following consumption of a high-fat diet so that, in healthy males, consumption of a high-fat, hypercaloric diet for 14 days is associated with marked acceleration of GE and mouth-to-cecum transit of a high-fat, solid test meal when compared with a low-fat diet (14). Moreover, in healthy young (15) and older (2) subjects, short-term glucose supplementation accelerates GE of a glucose drink, whereas fasting slows GE (10). That there were no differences in habitual fat or energy intake between the lean, overweight, and obese groups in our study is not surprising given that all subjects were weight-stable, and this could well account for the absence of any difference in GE between the groups.…”

Effect of obesity and major weight reduction on gastric emptying

“…Finally it should be noted that, in all of these studies, re-examination took place immediately after termination of the weight-reducing diet-intervention, and it is therefore impossible to distinguish between effects of the reduced weight and the possible effects of negative energy balance per se. 44,45 Recently, Teff et al have shown that increased activity in the parasympathetic efferent simulation of the stomach might be the mechanism that leads to an increased gastric emptying in obese subjects. 29 Another theory is that a higher initial emptying rate in obese individuals is caused by an adaptation to a high energy intake, or a high fat energy percentage.…”

Effects of acute dietary restriction on gut motor, hormone and energy intake responses to duodenal fat in obese men

“…The outcome of gut hormone measurements is also inconsistent, for example, some studies have reported lower fasting ghrelin, 15 higher fasting 18 and postprandial 16 plasma CCK, and lower postprandial PYY, 19 glucagon-like peptide-1 20 and ghrelin 21 concentrations, whereas others found no differences in PYY or glucagon-like peptide-1. 15 There is evidence that previous patterns of energy intake, in excess, in restriction and even when sustained for short periods of time, have the capacity to modify gastrointestinal function, 5,[22][23][24] and this may be of particular relevance to the inconsistent observations from studies relating to gastrointestinal function in the obese given that previous nutrient intake has not been quantified. For example, in healthy subjects, a 2-week period on a high-fat diet accelerates gastric emptying of a high-fat meal.…”

“…5 In contrast, fasting appears to have the opposite effect, so that after a 4-day fast, gastric emptying of glucose is slower in both lean and obese subjects. 22 The nutrient deprivation of critical illness is associated with delayed gastric emptying and increased plasma CCK and PYY concentrations, 23 with evidence that increased small-intestinal feedback contributes to the slowing of gastric emptying. 24 We have now evaluated, in obese subjects, the effects of short-term energy restriction on antropyloroduodenal (APD) motility, plasma CCK, PYY and ghrelin concentrations, and appetite and energy intake, in response to administration of intraduodenal lipid.…”