Exploring weight-related self-monitoring as a potential risk factor for eating disorder symptoms in adults - A systematic review and meta-analysis.

OBJECTIVE: Weight-related self-monitoring (WRSM), which involves the intentional tracking of body weight metrics, has been considered a potential risk factor for eating disorders. Therefore, the aim of this study was to systematically summarize the current state of the literature and to quantify the possible association between WRSM and eating disorder symptoms in adults. METHOD: Preregistration was carried out using PROSPERO (ID CRD42022366133). The PubMed, PsycInfo, and Web of Science databases were searched until December 21, 2023. A study had to be 1) be available in English or German, 2) be peer-reviewed and quantitative, 3) include adult participants (age ≥18 years) from the general population, 4) assess eating disorder symptoms via at least one of the following questionnaires: EDI, EAT, FEV, TFEQ, DEBQ, EDE-Q, Munich ED-Quest or IEG, and 5) include WRSM. Data analyses included descriptive analyses and three-level meta-analysis, corrected for correlations, for the global score and the different subscales of the eating disorder questionnaires. RESULTS: A total of 28 studies (n = 17,370 participants), with an overall fair methodological quality, were included in the systematic review. Out of these studies, nine studies with n = 13,507 participants were ultimately analyzed in the meta-analysis. The three-level meta-analysis did not reveal a significant association between WRSM and the eating disorder global score (r = 0.13, 95% CI [-0.02, 0.28]; p = 0.08), with this pattern also being evident in the subgroup analysis (diet monitoring). DISCUSSION: WRSM alone does not generally translate into an increased risk of disordered eating symptoms in the general population. We assume that individual factors are likely to determine whether the use of WRSM could lead to eating disorder symptoms. These factors should be accounted for in future research.

Exploring the Link between Lifestyle, Inflammation, and Insulin Resistance through an Improved Healthy Living Index.

Lifestyle factors-such as diet, physical activity (PA), smoking, and alcohol consumption-have a significant impact on mortality as well as healthcare costs. Moreover, they play a crucial role in the development of type 2 diabetes mellitus (DM2). There also seems to be a link between lifestyle behaviours and insulin resistance, which is often a precursor of DM2. This study uses an enhanced Healthy Living Index (HLI) integrating accelerometric data and an Ecological Momentary Assessment (EMA) to explore differences in lifestyle between insulin-sensitive (IS) and insulin-resistant (IR) individuals. Moreover, it explores the association between lifestyle behaviours and inflammation. Analysing data from 99 participants of the mPRIME study (57 women and 42 men; mean age 49.8 years), we calculated HLI scores-ranging from 0 to 4- based on adherence to specific low-risk lifestyle behaviours, including non-smoking, adhering to a healthy diet, maximally moderate alcohol consumption, and meeting World Health Organization (WHO) PA guidelines. Insulin sensitivity was assessed using a Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and C-reactive protein (CRP) levels were used as a proxy for inflammation. Lifestyle behaviours, represented by HLI scores, were significantly different between IS and IR individuals (U = 1529.0; p = 0.023). The difference in the HLI score between IR and IS individuals was mainly driven by lower adherence to PA recommendations in the IR group. Moreover, reduced PA was linked to increased CRP levels in the IR group (r = -0.368, p = 0.014). Our findings suggest that enhancing PA, especially among individuals with impaired insulin resistance, holds significant promise as a preventive strategy.

Impact of blood glucose on cognitive function in insulin resistance: novel insights from ambulatory assessment.

BACKGROUND/OBJECTIVES: Insulin resistance (IR)-related disorders and cognitive impairment lead to reduced quality of life and cause a significant strain on individuals and the public health system. Thus, we investigated the effects of insulin resistance (IR), and blood glucose fluctuations on cognitive function under laboratory and free-living conditions, using ecological momentary assessment (EMA). SUBJECTS/METHODS: Baseline assessments included neuropsychological tests and blood analysis. Individuals were classified as either insulin-sensitive (<2) or insulin-resistant (≥2), based on their Homeostatic Model Assessment (HOMA-IR) values. Continuous glucose monitoring (CGM) using a percutaneous sensor was performed for 1 week. Using multiple linear regression, we examined the effects of HOMA-IR and CGM metrics on cognitive domains. Working memory (WM) performance, which was assessed using EMA, 4 times a day for 3 consecutive days, was matched to short-term pre-task CGM metrics. Multilevel analysis was used to map the within-day associations of HOMA-IR, short-term CGM metrics, and WM. RESULTS: Analyses included 110 individuals (mean age 48.7 ± 14.3 years, 59% female, n = 53 insulin-resistant). IR was associated with lower global cognitive function (b = -0.267, P = 0.027), and WM (b = -0.316; P = 0.029), but not with executive function (b = -0.216; P = 0.154) during baseline. EMA showed that higher HOMA-IR was associated with lower within-day WM performance (ß = -0.20, 95% CI -0.40 to -0.00). CGM metrics were not associated with cognitive performance. CONCLUSIONS: The results confirm the association between IR and decrements in global cognitive functioning and WM, while no effects of CGM metrics were observed, making IR a crucial time point for intervention. Targeting underlying mechanisms (e.g., inflammation) in addition to glycemia could be promising to minimize adverse cognitive effects. Registered under https://drks.de/register/de identifier no. DRKS00022774.

Impact of insulin and insulin resistance on brain dopamine signalling and reward processing - An underexplored mechanism in the pathophysiology of depression?

Type 2 diabetes and major depressive disorder (MDD) are the leading causes of disability worldwide and have a high comorbidity rate with fatal outcomes. Despite the long-established association between these conditions, the underlying molecular mechanisms remain unknown. Since the discovery of insulin receptors in the brain and the brain's reward system, evidence has accumulated indicating that insulin modulates dopaminergic (DA) signalling and reward behaviour. Here, we review the evidence from rodent and human studies, that insulin resistance directly alters central DA pathways, which may result in motivational deficits and depressive symptoms. Specifically, we first elaborate on the differential effects of insulin on DA signalling in the ventral tegmental area (VTA) - the primary DA source region in the midbrain - and the striatum as well as its effects on behaviour. We then focus on the alterations induced by insulin deficiency and resistance. Finally, we review the impact of insulin resistance in DA pathways in promoting depressive symptoms and anhedonia on a molecular and epidemiological level and discuss its relevance for stratified treatment strategies.