Physiological Mechanisms Impacting Weight Regulation
Within the framework of body weight regulation, the first law of thermodynamics (i.e., the Law of Conservation of Energy - “Energy cannot be created nor destroyed, it simply is transferred from one form to another”) concisely and eloquently identifies the basic paradigm of body weight regulation, and is described by the equation below: Energy intake + Energy expenditure = ± Body weight
Therefore, the regulation of body weight is a balance between food intake and energy expenditure, where excess calories are stored as extra pounds and a deficit between intake and expenditure results in weight loss.
This chapter serves as a link between the treatment literature that might be recommended at a clinic, and the physiologic mechanisms underlying weight regulation. With this end in mind, we have chosen to present the chapter in two parts—with the first looking at the control of energy expenditure and the second looking at the physiology of appetite regulation. The section on control of energy expenditure will focus on a distinct aspect of physical activity—spontaneous free-living energy expenditure—and attempt to answer the basic question of why it is so hard for some people to be physically active. The section on the physiology of appetite regulation will focus on signaling pathways (both neural-peptides and hormones) originating from three distinct regions: a) adipose tissue, b) gastrointestinal system and pancreas, and c) the central nervous system.
KeywordsPhysical Activity Food Intake Pancreatic Polypeptide Arcuate Nucleus Reduce Food Intake
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