Biological control of appetite: A daunting complexity

Abstract

ObjectiveThis review summarizes a portion of the discussions of an NIH Workshop (Bethesda, MD, 2015) entitled, “Self-Regulation of Appetite, It's Complicated,” which focused on the biological aspects of appetite regulation.MethodsHere we summarize the key biological inputs of appetite regulation and their implications for body weight regulation.ResultsThese discussions offer an update of the long-held, rigid perspective of an “adipocentric” biological control, taking a broader view that also includes important inputs from the digestive tract, from lean mass, and from the chemical sensory systems underlying taste and smell. We are only beginning to understand how these biological systems are integrated and how this integrated input influences appetite and food eating behaviors. The relevance of these biological inputs was discussed primarily in the context of obesity and the problem of weight regain, touching on topics related to the biological predisposition for obesity and the impact that obesity treatments (dieting, exercise, bariatric surgery, etc.) might have on appetite and weight loss maintenance. Finally, we consider a common theme that pervaded the workshop discussions, which was individual variability.ConclusionsIt is this individual variability in the predisposition for obesity and in the biological response to weight loss that makes the biological component of appetite regulation so complicated. When this individual biological variability is placed in the context of the diverse environmental and behavioral pressures that also influence food eating behaviors, it is easy to appreciate the daunting complexities that arise with the self-regulation of appetite.

Biology of obesity and weight regain

“…Research also shows that repeated attempts to lose weight do not abolish the physiological adaptation that leads to weight regain; nor do they correct any underlying genetic or environmental disruptions in the processes of converting fuel to energy and maintaining energy balance. The biological pressures to increase feeding and decrease energy expenditure “do not resolve with time after weight loss; rather they may even strengthen with time during weight loss maintenance” (MacLean, Blundell, Mennella, & Batterham, , pp. S12–S13).…”

“…The negative energy balance in turn sets the stage for unintentional weight regain following successful weight loss. The genetic variability in predisposition to obesity and biological adaptation to weight loss have led MacLean, Blundell, Menella, and Batterham () to call self‐regulation of appetite and eating behavior “a daunting complexity.” Because this “daunting complexity” is fundamental to the clinical management of obesity, the purpose of this article is to describe the normal physiological processes regulating energy balance. Disruptions in energy regulation leading to the development of obesity will be discussed, and the physiological adaptations associated with weight loss and regain will be described, along with implications for clinical practice.…”

Biobehavioural approaches to prevention and treatment: A call for implementation science in obesity research

“…Two years prior to this IOM report, the use of the term “biobehavioural” as related to obesity can be found . Decades of previous work have gone deeply into discovering detailed mechanisms to understand the contributing factors driving obesity and its complications, and by leveraging these discoveries from recent decades, scientists in our community can develop new and creative approaches using the biobehavioural framework. This mechanistic research has resulted in a broad but fragmented literature base that needs to be more fully integrated into a systems approach.…”

“…Traditionally, behavioural scientists have strictly examined behavioural influences in the progression and treatment of obesity, while experts in basic sciences have investigated specific physiological processes. A push to integrate these two areas of research exists, and progress has been made; but thus far, obesity research has largely taken a behavioural or biological approach to the disease. Historically, this is due to a variety of factors including departmental and funding silos.…”

Epidemiology of Obesity and Pharmacologic Treatment Options

“…Weight loss improves many of the metabolic and fat mass diseases, lowers healthcare costs, and improves quality of life 18 – 22 . However, lifestyle modifications, which are the mainstay of obesity management, are difficult to maintain for several reasons, including changes in counterregulatory hormonal signals that increase food intake and decrease metabolism and energy expenditure 23 – 27 . Until recently, sustained weight loss was achieved only by surgical means.…”