The impacts of COVID-19 on childhood obesity: prevalence, contributing factors, and implications for management

PURPOSE

This study aimed to identify changes in the prevalence of obesity and related diseases among children and adolescents during the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This study was conducted using data from the 2016-2021 Korean National Health and Nutrition Examination Survey and included 3,861 children and adolescents aged 10-18 years. The prevalence of obesity and related diseases was adjusted for age, sex, and income. We also analyzed the socioeconomic, nutritional, and physical activity items in the survey.

RESULTS

During the COVID-19 pandemic, there was a significant increase in the prevalence of obesity (p=0.02), central obesity (p=0.001), mean body mass index (BMI, p=0.03), and hemoglobin A1c (p=0.005) among children and adolescents aged 10-18 years. The intake of food and calories was significantly reduced in the normal-weight group (p=0.001 and <0.001) but not in the obese group. Incidences of skipping breakfast increased and eating out decreased, regardless of obesity status. However, the changes in health behaviors were not significant. The prevalence of central obesity and increased BMI showed a significant linear association between children and their parents, especially in the 10-12-year-old age group. A clear increase in the proportion of metabolically unhealthy children and adolescents was observed in the obese group, and the frequency of central obesity in parents also increased.

CONCLUSION

The number of metabolically unhealthy, obese children and adolescents increased during the COVID-19 pandemic. Age-specific strategies that consider growth, development, and genetic and social factors are required. Health strategies targeting the entire family are required to develop healthier habits.

Hepatalin: the missing link in prediabetes, obesity, and type 2 diabetes

Hepatalin is a hormone secreted by the liver in response to pulses of insulin after a mixed nutrient meal, but only if the liver receives two permissive synergistic feeding signals from the stomach. Hepatalin stimulates glucose uptake and storage as glycogen in skeletal muscle, heart, and kidney but not liver, intestines, or adipocytes. Insulin acts primarily on liver and fat. Reduced hepatalin action results in postprandial hyperglycemia, compensatory elevation of insulin secretion, and a resultant shift in partitioning of nutrient energy storage from glycogen in muscle, to fat. Chronic hepatalin suppression leads to a predictable chronology of dysfunctions, first diagnosable as Absence of Meal-induced Insulin Sensitization (AMIS) which progresses to prediabetes, adiposity, and type 2 diabetes. The focus on nutrient partitioning and the role of hepatalin allows AMIS to be diagnosed, prevented, and treated, including through the use of lifestyle interventions.

Driver versus navigator causation in biology: the case of insulin and fasting glucose

BACKGROUND

In biomedicine, inferring causal relation from experimental intervention or perturbation is believed to be a more reliable approach than inferring causation from cross-sectional correlation. However, we point out here that even in interventional inference there are logical traps. In homeostatic systems, causality in a steady state can be qualitatively different from that in a perturbed state. On a broader scale there is a need to differentiate driver causality from navigator causality. A driver is essential for reaching a destination but may not have any role in deciding the destination. A navigator on the other hand has a role in deciding the destination and the path but may not be able to drive the system to the destination. The failure to differentiate between types of causalities is likely to have resulted into many misinterpretations in physiology and biomedicine.

METHODS

We illustrate this by critically re-examining a specific case of the causal role of insulin in glucose homeostasis using five different approaches (1) Systematic review of tissue specific insulin receptor knock-outs, (2) Systematic review of insulin suppression and insulin enhancement experiments, (3) Differentiating steady state and post-meal state glucose levels in streptozotocin treated rats in primary experiments, (4) Mathematical and theoretical considerations and (5) Glucose-insulin relationship in human epidemiological data.

RESULTS

All the approaches converge on the inference that although insulin action hastens the return to a steady state after a glucose load, there is no evidence that insulin action determines the steady state level of glucose. Insulin, unlike the popular belief in medicine, appears to be a driver but not a navigator for steady state glucose level. It is quite likely therefore that the current line of clinical action in the field of type 2 diabetes has limited success largely because it is based on a misinterpretation of glucose-insulin relationship. The insulin-glucose example suggests that we may have to carefully re-examine causal inferences from perturbation experiments and set up revised norms for experimental design for causal inference.

Metabolic and inflammatory postprandial effect of a highly saturated fat meal and its relationship to abdominal obesity

Introduction: The postprandial stage is associated with the increase of markers related to cardiovascular risk, and its intensity depends on the metabolic state. Objective: To determine the impact of a high-fat meal intake on the metabolic and inflammatory profile, and its relationship to abdominal obesity. Materials and methods: This clinical trial included 42 individuals (21 with abdominal obesity). We measured glucose, insulin, lipid profile, reactive C protein, lipopolysaccharides, and interleukin 6 in fasting blood, and four hours after eating. Results: Besides obesity, we found insulin resistance and higher levels of fasting triacylglycerides and C-reactive protein. There were higher postprandial responses to glucose, insulin, and triacylglycerides. Interleukin 6 decreased in the non-obese group, and lipopolysaccharides increased in both groups. Conclusions: A saturated high-fat food intake produced a greater impact on the glycemic variables in the group with obesity, while it affected the lipids in both groups. However, the increase of triacylglycerides was higher in the presence of a high basal concentration, and it promoted the increase of lipopolysaccharides. The basal and postprandial inflammatory state affected the group with obesity more. The postprandial moment reflected the most frequent state of the individuals on a normal day and evidenced the capacity of the metabolic response to food intake, as well as early metabolic risk states.

Obesity as an Early Symptom of the AMIS Syndrome

We review evidence that the AMIS (Absence of Meal-induced Insulin Sensitization) syndrome describes a paradigm fundamental to development of obesity. The hypoglycemic response to a pulse of insulin is doubled after a meal as a result of Hepatic Insulin Sensitizing Substance (HISS), released from the liver to act selectively on muscle, heart and kidney. In the absence of HISS action, the hypoglycemic response to insulin is the same as in the fasted state, and only half of what it should be. Postprandial hyperglycemia ensues, with compensatory hyperinsulinemia, resultant hyperlipidemia and elevated free radical stress. Storage of nutrient energy shifts from glycogen in muscle to fat. Chronic AMIS results in adiposity, occurs with age, is accelerated with sucrose supplement, and prevented by a synergistic antioxidant. Exercise reverses AMIS, as do pharmaceuticals that mimic the "feeding signals". The AMIS syndrome develops as a sequence of pathologies based on the consequences of absence of HISS action, including adiposity as the earliest symptom. Cardiac dysfunction, hypertension, hypercholesterolemia, and fatty liver are related to lack of HISS action. The AMIS syndrome hypothesis is mechanistic-based and accounts for the major pathologies associated with prediabetes, obesity, diabetes and metabolic syndrome. AMIS can be diagnosed, prevented and treated.

Insulin resistance correlates with the arterial stiffness before glucose intolerance

OBJECTIVE

The elevated plasma glucose level and/or insulin resistance in diabetes or impaired glucose tolerance play important roles in the pathogenesis of arterial stiffness. The present study investigated whether insulin resistance correlated with arterial stiffness before the development of glucose intolerance.

METHODS

We conducted a cross-sectional analysis in 872 young to middle-age individuals with normal glucose tolerance (aged 36.2±8.5 years, BMI 24.6±3.1 kg/m2 [mean±SD]). The homeostasis model assessment (HOMA) index was used as a quantitative assessment of the fasting insulin resistance (FIR), and the plasma insulin level after glucose loading was adopted as an index of the post-challenge insulin resistance (PIR). The Matsuda index [ISI (composite)] was used as a measurement of the insulin sensitivity. The arterial stiffness assessed by the brachial-ankle pulse wave velocity (baPWV) was adopted to quantify its independent associations with insulin resistance.

RESULTS

The univariate linear regression analysis indicated that the fasting plasma glucose level (FPG, β = 68.2; 95% CI 40.9, 95.6; p<0.001), post-challenge plasma glucose level (PPG, β = 25.3; 95% CI 15.6, 35.0; p<0.001), FIR (β = 24.5; 95% CI 14.1, 35.0; p<0.001), PIR (β=1.30; 95% CI 0.87, 1.73; p<0.001) and ISI (composite) (β = -3.55; 95% CI -5.02, -2.07; p<0.001) were all significantly correlated with the baPWV. After adjustment for sex, age, BMI, heart rate, smoking, systolic blood pressure, total cholesterol, LDL-cholesterol and family history of diabetes, the multivariate linear regression analysis demonstrated that the PIR (model 1, β = 0.39, p=0.038; model 2, β = 0.39, p=0.035; model 3, β = 0.39, p=0.035) was an independent contributor to the baPWV, while the FIR, FPG, PPG and ISI (composite) failed to show any significant contribution.

CONCLUSION

The insulin resistance correlated with the arterial stiffness before glucose intolerance.