Factors That Influence How Much We Eat
The motivational state that cause us to stop eating a meal when there is food re-maining is satiety. Satiety mechanisms play a major role in determining how much we eat.
satiety signals. As you will learn in the next section of the chapter, food in the gut and glucose entering the blood can induce satiety signals which inhibit subsequent consumption. These signals depend on both the volume and the nutritive density (calories per unit volume) of food. The effects of nutritive density have been demonstrated in studies in which laboratory rats have been maintained on single diet.Once a stable baseline of consumption has been established, the nutritive density of the diet is changed. Some rats learn to adjust the volume of food they consume to keep their caloric intake and body weights relatively stable. However, there are limits to this adjustment: Most rats do not increase their intake sufficiently to maintain their body weights if the nutritive density of their conventional laboratory feed is reduced by more than 50%. Moreover, they do not maintain the consistency of their caloric intake as set-point theories predict they should, if there is a major change in the palatability of their diet.
Sham Eating. The Study of sham eating กd Sham indicates that satiety signals from the gut or blood are not necessary to terminate a meal.In Sham-eating experiments, food Chewed and Swallowed by the subject : but rather than passing down subject's esophagus into the stomach, the food passes out of the body through an implanted tube (see figure 10.7)
Because Sham eating adds no energy to the body , set-point theories predict that all sham-eaten meals should be huge. But this is not the case. Weingarten and Kulikovsky (1989) Sham fed rats diet that they had naturally eaten many times be- tore .The first Sham meal was the same size as the previously eaten meals; then, on ensuing days the rats began to sham eat more and more (See Figure 0.