Sham feeding

Sham feeding is a research technique used in the study of digestive processes, particularly to understand the mechanisms of satiation and digestion. It involves allowing an animal or sometimes a human to eat food that is not actually digested, as the food exits the body before reaching the stomach or is otherwise prevented from being digested. This method is used to study the cephalic phase of digestion and the sensory aspects of eating without the confounding effects of nutrient absorption.

Overview

Sham feeding experiments typically involve the use of a fistula, a surgically created opening that allows food to exit the body directly after being chewed and swallowed. In animals, this is often achieved through a procedure known as a Pavlov pouch, named after the Russian physiologist Ivan Pavlov, who pioneered studies in classical conditioning and digestive physiology. In humans, sham feeding can be simulated through less invasive means, such as spitting out the food.

The primary purpose of sham feeding is to activate the cephalic phase responses of digestion, which are triggered by the sight, smell, taste, and thought of food. This phase involves the release of digestive enzymes and hormones, such as saliva, gastric juice, and insulin, in preparation for food digestion. By studying sham feeding, researchers can isolate the effects of these sensory and cognitive aspects of eating from the metabolic effects of nutrient absorption.

Applications

Sham feeding has been used in various research contexts, including:

• Understanding the role of sensory perception in the regulation of appetite and food intake.
• Investigating the mechanisms behind the cephalic phase of digestion.
• Studying the effects of different foods or nutrients on digestive enzyme and hormone release.
• Exploring the pathophysiology of eating disorders and obesity.

Ethical Considerations

Sham feeding studies, especially those involving animals, are subject to ethical considerations. The welfare of the subjects must be taken into account, and such studies are typically conducted under strict ethical guidelines to ensure that discomfort and harm are minimized.

Limitations

While sham feeding provides valuable insights into the sensory and cognitive aspects of eating, it does not fully replicate the complex process of digestion and nutrient absorption. Therefore, findings from sham feeding studies must be interpreted within the context of these limitations.

See Also

• Digestive system
• Appetite
• Ivan Pavlov
• Obesity
• Eating disorders