Adiponectin in anorexia nervosa and its modifiers: A meta‐regression study

Abstract

Objective: Adiponectin, which is secreted from adipose tissue, is a protein hormone.Although a large body of studies have found that circulating adiponectin levels increase in anorexia nervosa (AN) and caloric restriction, the effect of subtypes of AN and modifiers of adiponectin in AN are not yet known.Methods: A systematic search of electronic databases was performed using the search terms "adiponectin," "anorexia nervosa," and "eating disorder" up to January 2021. All studies published in peer-reviewed journals, which included cases and control groups, were selected. The main outcome was the pooled standardized mean difference (SMD) in adiponectin levels between cases and controls, using the random-effects model. Modifiers of SMD were tested via meta-regression. Heterogeneity and publication bias were evaluated.Results: Thirty-four studies met all eligibility criteria. The total sample of AN participants (Hedges' g = .765, p < .0001), and specifically the binge-eating/purging (Hedges' g = 1.211, p < .00001) and restrictive subtypes (Hedges' g = .913, p < .00001) of AN have increased adiponectin plasma levels compared with healthy controls. Meta-regression determined that insulin, IGF-1, BMI, triglyceride, resistin, glucose, IL-6 levels are significant modifiers of adiponectin levels.Discussion: Compared with controls, adiponectin levels are higher in AN overall, and specifically in the binge-eating/purging and the restrictive AN subtypes. Many of metabolic parameters of glucose metabolism and pro-inflammatory molecules modify the relationship between AN and adiponectin levels. Adipose tissue is important to maintain metabolic stability.Public Significance: Anorexia nervosa is a psychiatric disorder associated with a severe decrease in body weight and multiple metabolic abnormalities, including an increase in the hormone adiponectin. In this paper, we used meta-analysis, a powerful statistical method, to aggregate data from 34 rigorously selected research reports. This enabled us to understand the value of adiponectin to differentiate clinical subtypes of anorexia nervosa and the relations between adiponectin and other important metabolic parameters.

Endocrinology of Underweight and Anorexia Nervosa

“…It is a protein secreted by adipose tissue and is inversely related to BMI. As in other forms of underweight and cachexia, adiponectin is elevated in anorexia [ 37 , 38 , 39 , 40 , 41 , 42 ] and has been reported to be lower, similar, or higher in other forms of eating disorders compared with controls [ 38 , 43 ] and decreases with refeeding, as expected [ 44 ]. The role of adiponectin in the regulation of appetite and food intake remains unclear [ 45 ].…”

Comparison of Adiponectin Levels in Anorexia Nervosa, Bulimia Nervosa, Binge-Eating Disorder, Obesity, Constitutional Thinness, and Healthy Controls: A Network Meta-Analysis

“…These aforementioned symptoms are not observed in constitutionally thin people and may therefore constitute the line between health and disease. Previous studies have also shown significant relationships between various inflammatory factors and adiponectin [ 15 , 24 , 44 ]. The current findings further highlight the role of heavily disturbed general body functions in AN compared to constitutional thinness.…”

“…Adiponectin levels can also be affected by the presence of eating disorders, especially AN. Two meta-analyses have confirmed significantly increased levels of adiponectin in AN compared to healthy controls [ 14 , 15 ]. However, it is not clear whether constitutional thinness (C.Thin) is associated with increased adiponectin levels compared to those of healthy controls [ 16 , 17 , 18 ].…”

Modified activity-based anorexia paradigm dampens chronic food restriction-induced hyperadiponectinemia in adolescent female mice

“…Although adiponectin is an appetite-regulating cytokine secreted from adipose tissue, the blood adiponectin level is negatively correlated with body mass index (BMI) and body fat mass [17]. In line with this, most studies and a recent metaanalysis reported that patients with AN exhibited hyperadiponectinemia, which is normalized during refeeding [18,19]. However, elevated blood adiponectin has been observed not only in AN patients, but also in healthy underweight young people (BMI < 18.5) [20].…”

“…In spite of this being an adipose-derived hormone, it is of interest that the blood adiponectin level is inversely correlated with BMI and body fat mass [17]. Thus, many clinical studies and reviews report that hyperadiponectinemia is frequently observed in AN patients [18,19,[39][40][41][42][43]. In studies of rodents, the blood adiponectin level was not changed by shortterm caloric restriction and/or exercise [44][45][46].…”