It is essential that we understand the normal physiological mechanism that makes us feel the hunger and the mechanisms of absorption and control of ingested food amounts as well as the consequences produced by weight gain as adipose tissues increase and the development of many kinds of diseases. The need to eat involves a sequence of control mechanisms. Eating is necessary for a variety of our organs’ functions, be it growth or absorption of micronutrients like vitamins and minerals and macronutrients like carbohydrates, fat, proteins, and water. Obesity surgery radically modifies this entire system, and understanding the consequences of these modifications is essential.
We understand that our body has several mechanisms to control food ingestion and absorption. We also know that basically the central nervous system (CNS), through the hypothalamus, fatty tissue, and the signals produced by a variety of hormones in our digestive system, provides this control.
The majority of obesity surgery techniques involve a radical alteration in the digestive tract, therefore resulting in a totally different way of intestinal hormone stimulation and production. With weight loss, there is a complete modification in the morphology and physiology of the adipose tissues, be it visceral or parietal (it is now well-known that this tissue is a powerful “endocrine organ”). The CNS, obviously, will also receive and produce these signals differently. In other words, obesity surgery is not merely a surgery technique, but a metabolic surgery that also implicates a variety of undiscovered mysteries.
The system that controls these mechanisms has both afferent and efferent signals. The afferent ones will be determined by many stimuli beyond the need or surplus of energy accumulation and may or may not work together (see Tables 5–1 and 5–2). The CNS and, specifically, the hypothalamus will manage the efferent signs, mainly the need or not for us to accumulate or burn more energy, as well as our hunger (this topic will be discussed in detail below).
Table 5–1. Afferent Signals
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Table 5–1. Afferent Signals
Signals coming from digestive tract
Afferent signals descendant from fat tissue
Afferent signals descendant from pancreas
Table 5–2. Efferent Signals
Since survival is more acutely threatened by starvation than obesity, it should come as no surprise that this system is more robustly organized to galvanize in response to deficient energy intake and stores than to excess energy.1 Since this complex protection system will only engage after obesity surgery, it is essential that we continue to increase our understanding of it.
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