About this Research Topic
Obesity is associated with metabolic dysfunction and increased risk for cardiometabolic disease. However, in recent decades it has become apparent that not all subjects with obesity present with an abnormal cardiometabolic profile, just as not all lean subjects (i.e., those without overweight or obesity) are necessarily free of metabolic risk factors. Prospective studies have demonstrated that the presence of metabolic dysfunction confers a greater risk for cardiometabolic disease than the presence of obesity per se; likewise, absence of metabolic dysfunction shields against the development of cardiometabolic disease to a greater extent than absence of excess body weight.
About 10–50% of obese people are metabolically healthy and about 5–45% of lean people are metabolically unhealthy. The mere existence of these phenotypes implies that obesity treatment efforts need not necessarily focus on all people with obesity, and likewise, screening programs should be developed to better identify lean people with metabolic dysfunction. There is data to suggest that deposition of fat in the upper body (e.g., visceral adipose tissue) and the liver are markers of metabolic disease, whereas deposition of fat in the lower body, the ability to secrete insulin and the sensitivity to insulin, and aerobic fitness are markers of metabolic health. It is not known whether these phenotypic traits are causally linked to the maintenance or the disturbance of metabolic homeostasis; how much of these traits are genetically and epigenetically determined; and what is the contribution of environmental factors such as diet and exercise. Importantly, the effects of therapeutic interventions such as dietary modifications with or without energy restriction and weight loss in these phenotypes are not entirely clear.
This Research Topic welcomes papers dealing with metabolically healthy and unhealthy lean and obese phenotypes in regards to definition and prevalence; genetics; physiological traits; stability over time; and response to lifestyle interventions such as weight loss, changes in the diet without weight loss, and physical activity. This Research Topic aims to further enhance our understanding of the importance of metabolic function for health, independent of body weight and adiposity.
We welcome Original Research articles including randomized and non-randomized clinical trials, as well as cross-sectional studies, Narrative and Systematic Reviews, Perspectives, and Opinions on themes such as, but not limited to:
• Estimates of prevalence across countries and importance of using different definitions
• Role of genetic variation and environmental factors in determining the physiological traits of metabolic health and disease in lean and obese subjects
• Diet and physical activity habits of metabolically healthy obese and metabolically unhealthy lean subjects
• Effects of weight loss interventions (including lifestyle modifications such as diet and/or exercise) in metabolically healthy vs metabolically unhealthy people with obesity
• Effects of dietary modifications with and without caloric restriction in metabolically unhealthy lean people
Keywords: Body Fat Distribution, Visceral Adipose Tissue, Exercise, Liver Fat, Insulin Resistance, Insulin Secretion
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.
