Hepatic insulin clearance increases after weight loss in obese children and adolescents

Consequences on islet and incretin hormone responses to dinner by omission of lunch in healthy men

BACKGROUND

Omission of breakfast results in higher glucose and lower insulin and incretin hormone levels after both lunch and dinner. Whether omission of lunch has a similar impact on the following meal is not known.

AIM

This study therefore explored whether omission of lunch ingestion affects glucose, islet and incretin hormones after dinner ingestion in healthy subjects.

MATERIALS & METHODS

Twelve male volunteers (mean age 22 years, BMI 22.5 kg/m2) underwent two test days in random order with standard breakfast and dinner on both days with provision or omission of standard lunch in between.

RESULTS

The results showed that throughout the 300 minutes study period, glucose, insulin, glucagon and GIP levels after dinner ingestion did not differ between the two tests. In contrast, C-peptide, and GLP-1 levels were 26%-35% higher at later time points after dinner ingestion when lunch had been omitted (P < .05).

CONCLUSION

We conclude that omission of lunch increases GLP-1 and insulin secretion and possibly also insulin clearance resulting in unchanged glucose and insulin levels after dinner ingestion.

Adolescents' and Parents' Perspectives of a Revised Protein-Sparing Modified Fast (rPSMF) for Severe Obesity

The purpose of this pilot study was to assess the acceptability to adolescents (11-18 years old) and their parents using a revised protein-sparing modified fast (rPSMF) for 12 months as an intervention for severe obesity in a tertiary pediatric weight management clinic (PWMC). To assess acceptability (satisfaction, confidence) with the rPSMF protocol, surveys were completed by adolescents and parents at baseline, 1, 3, 6, and 12 months, with adolescent height and weight measured. Analyses were conducted to assess differences in satisfaction and confidence based on adolescent response (weight loss) and adherence to the rPSMF. Adolescents' adherence with the rPSMF was close to 50% in the first 3 months, but dropped to 14.7% at 6 months. Adolescents were most confident with choosing low carbohydrate foods at baseline. Over 12 months, adolescents and parents reported weight loss as "the most liked" part of the rPSMF. Adolescents who were adherent were more satisfied with their weight loss than their non-adherent peers. Parents and adolescents reported lack of food variety and difficulty following the protocol as challenges with the rPSMF. Adolescents and their parents were able to follow the rPSMF protocol, with weight loss, but with decreased adherence over time.

Rationale and design of a pilot study to evaluate the acceptability and effectiveness of a revised protein sparing modified fast (rPSMF) for severe obesity in a pediatric tertiary care weight management clinic

Aggressive dietary interventions may provide an accessible treatment option for children and adolescents with severe obesity who are not successful with traditional lifestyle behavioral interventions or do not want or qualify for weight loss surgery. One such intensive dietary option is the protein sparing modified fast (PSMF). The PSMF involves minimal carbohydrate intake to induce ketosis, while maintaining adequate or high protein intake to minimize catabolism. The PSMF, under medical supervision, can be an effective and safe intervention for children and adolescents, yet the PSMF diet is not regularly used in the treatment of pediatric severe obesity. This paper describes the rationale and design for a pilot study to evaluate the acceptability and effectiveness of a revised PSMF (rPSMF) implemented as a weight loss treatment option for children and adolescents with severe obesity in a pediatric tertiary care weight management clinic. The primary aim of the study is to evaluate the acceptability of the rPSMF as assessed by adherence, satisfaction with the intervention, and participation rate using quantitative and qualitative methods. The secondary aim is to investigate the effectiveness of the rPSMF on improving a) anthropometric measures (weight, body mass index [BMI], BMI z-score); b) metabolic measures (lipid profile, glycosylated hemoglobin, liver function tests); and c) quality of life. Results of this study will provide guidance for the standardization of a pediatric rPSMF protocol in a clinic setting, delineate which factors improve or hinder adherence and weight loss and provide preliminary data for a multicenter randomized controlled trial.

CLINICALTRIALSGOV IDENTIFIER

NCT03899311.

Efficacy of very low-energy diet programs for weight loss: A systematic review with meta-analysis of intervention studies in children and adolescents with obesity

The objective of this review was to evaluate the efficacy and safety of very low-energy diet (VLED) programs for weight loss in children and adolescents with obesity. Six electronic databases were searched identifying 24 eligible studies (16 pre-post studies, four nonrandomized trials, two randomized controlled trials [RCTs], and two chart reviews) published up to October 2018. Studies were in English, implemented a VLED (≤3360 kJF/day [≤800 kcal/day] or <50% estimated energy requirements) in 5- to 18-year-olds with obesity, and reported at least one weight-related outcome. Weight-related outcomes significantly improved postintervention in all studies. Meta-analysis of 20 studies indicated a mean 10.1 kg (95% confidence interval [CI], 8.7-11.4 kg, P < 0.001; I²  = 92.3%) weight loss following interventions lasting 3 to 20 weeks. Moderator analysis indicated greater weight loss in adolescent-only studies (10-18 years) and formulated meal replacement interventions and inpatient settings. Meta-analysis of seven studies reporting weight at follow-up (5-14.5 months from baseline) indicated 5.3 kg mean weight loss (CI, 2.5-8.0 kg, P < 0.001; I²  = 50.6%). Details of adverse events were limited. VLED programs are effective for treating children and adolescents with obesity. However, conclusions on their safety cannot be drawn from the existing literature at this time. Future studies should include long-term follow-up with ongoing support and comprehensive monitoring of all adverse events.

Determinants of longitudinal change in insulin clearance: the Prospective Metabolism and Islet Cell Evaluation cohort

OBJECTIVE

To evaluate multiple determinants of the longitudinal change in insulin clearance (IC) in subjects at high risk for type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

Adults (n=492) at risk for T2D in the Prospective Metabolism and Islet Cell Evaluation cohort, a longitudinal observational cohort, had four visits over 9 years. Values from oral glucose tolerance tests collected at each assessment were used to calculate the ratios of both fasting C peptide-to-insulin (IC_FASTING) and areas under the curve of C peptide-to-insulin (IC_AUC). Generalized estimating equations (GEE) evaluated multiple determinants of longitudinal changes in IC.

RESULTS

IC declined by 20% over the 9-year follow-up period (p<0.05). Primary GEE results indicated that non-European ethnicity, as well as increases in baseline measures of waist circumference, white cell count, and alanine aminotransferase, was associated with declines in IC_FASTING and IC_AUC over time (all p<0.05). There were no significant associations of IC with sex, age, physical activity, smoking, or family history of T2D. Both baseline and longitudinal IC were associated with incident dysglycemia.

CONCLUSIONS

Our findings suggest that non-European ethnicity and components of the metabolic syndrome, including central obesity, non-alcoholic fatty liver disease, and subclinical inflammation, may be related to longitudinal declines in IC.

Acute Exercise Improves Insulin Clearance and Increases the Expression of Insulin-Degrading Enzyme in the Liver and Skeletal Muscle of Swiss Mice

The effects of exercise on insulin clearance and IDE expression are not yet fully elucidated. Here, we have explored the effect of acute exercise on insulin clearance and IDE expression in lean mice. Male Swiss mice were subjected to a single bout of exercise on a speed/angle controlled treadmill for 3-h at approximately 60-70% of maximum oxygen consumption. As expected, acute exercise reduced glycemia and insulinemia, and increased insulin tolerance. The activity of AMPK-ACC, but not of IR-Akt, pathway was increased in the liver and skeletal muscle of trained mice. In an apparent contrast to the reduced insulinemia, glucose-stimulated insulin secretion was increased in isolated islets of these mice. However, insulin clearance was increased after acute exercise and was accompanied by increased expression of the insulin-degrading enzyme (IDE), in the liver and skeletal muscle. Finally, C2C12, but not HEPG2 cells, incubated at different concentrations of 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) for 3-h, showed increased expression of IDE. In conclusion, acute exercise increases insulin clearance, probably due to an augmentation of IDE expression in the liver and skeletal muscle. The elevated IDE expression, in the skeletal muscle, seems to be mediated by activation of AMPK-ACC pathway, in response to exercise. We believe that the increase in the IDE expression, comprise a safety measure to maintain glycemia at or close to physiological levels, turning physical exercise more effective and safe.

Forced Hepatic Overexpression of CEACAM1 Curtails Diet-Induced Insulin Resistance

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates insulin sensitivity by promoting hepatic insulin clearance. Liver-specific inactivation or global null-mutation of Ceacam1 impairs hepatic insulin extraction to cause chronic hyperinsulinemia, resulting in insulin resistance and visceral obesity. In this study we investigated whether diet-induced insulin resistance implicates changes in hepatic CEACAM1. We report that feeding C57/BL6J mice a high-fat diet reduced hepatic CEACAM1 levels by >50% beginning at 21 days, causing hyperinsulinemia, insulin resistance, and elevation in hepatic triacylglycerol content. Conversely, liver-specific inducible CEACAM1 expression prevented hyperinsulinemia and markedly limited insulin resistance and hepatic lipid accumulation that were induced by prolonged high-fat intake. This was partly mediated by increased hepatic β-fatty acid oxidation and energy expenditure. The data demonstrate that the high-fat diet reduced hepatic CEACAM1 expression and that overexpressing CEACAM1 in liver curtailed diet-induced metabolic abnormalities by protecting hepatic insulin clearance.

Effects of resistance training on metabolic fitness in children and adolescents: a systematic review

The majority of resistance training (RT) research with children to date has focused on pre-adolescents and the safety and efficacy of this type of training rather than the potential metabolic health benefits. Our objectives, using computerized databases, were (i) to systematically review studies utilizing RT interventions with children and adolescents <18 years; (ii) to investigate the metabolic health outcomes (adiposity, lipids, insulin, glucose) associated with RT; (iii) to provide recommendations for future investigations. A total of 12 studies met the review criteria. There is only a small amount of evidence that children and adolescents may derive metabolic health-related adaptations from supervised RT. However, methodological limitations within the body of this literature make it difficult to determine the optimal RT prescription for metabolic fitness in children and adolescents, and the extent and duration of such benefits. More robustly designed single modality randomized controlled trials utilizing standardized reporting and precise outcome assessments are required to determine the extent of health outcomes attributable solely to RT and to enable the development of evidence-based obesity prevention and treatment strategies in this cohort.

Factors that alter body fat, body mass, and fat-free mass in pediatric obesity

PURPOSE

The purpose of this study was to quantify the effects of exercise treatment programs on changes in body mass, fat-free mass, and body fat in obese children and adolescents.

METHODS

By using the meta-analytic approach, studies that met the following criteria were included in our analyses: 1) at least six subjects per group; 2) subject groups consisting of children in the 5- to 17-yr age range; 3) pretest and posttest values for either body mass, percent body fat, or fat-free mass (FFM); 4) used exercise as a mode of treatment (e.g., walking, jogging, cycle ergometry, high-repetition resistance exercise, and combinations); 6) training programs >or= 3 wk; 7) full-length publications (not conference proceedings); 8) apparently "healthy" children (i.e., free from endocrine diseases and disorders); and 9) published studies in English language journals only.

RESULTS

A total of 120 investigations were located that addressed the issue of exercise as a method of treatment in pediatric obesity. Of those, 30 met our criteria for inclusion. Across all designs and categories, fixed-effects modeling yielded significant decreases in the following dependent variables: 1) percent body fat (mean = 0.70 +/- 0.35; 95% CI = 0.21 to 1.1); 2) FFM (mean = 0.50 +/- 0.38; 95% CI = 0.03 to 0.57); 3) body mass (mean = 0.34 +/- 0.18; 95% CI = 0.01 to 0.46); 4) BMI (mean = 0.76 +/- 0.55; 95% CI = 4.24 to 1.7), and 5) VO2max (mean = 0.52 +/- 0.16; 95% CI = 0.18 to 0.89), respectively. Significant differences were found as a function of the type intervention groups (exercise vs exercise + behavioral modification; P < 0.04); body composition assessment methods (skinfold vs hydrostatic weighing, DEXA, and total body water; P < 0.006); exercise intensity (60-65%, vs >or= 71% VO2max; P < 0.01); duration (<or= 30 min vs > 30 min; P < 0.03); and mode (aerobic vs aerobic + resistance training; P < 0.02). Stepwise linear regression suggested that initial body fat levels (or body mass), type of treatment intervention, exercise intensity, and exercise mode accounted for most of the variance associated with changes in body composition after training.

CONCLUSIONS

Exercise is efficacious for reducing selected body composition variables in children and adolescents. The most favorable alterations in body composition occurred with 1) low-intensity, long-duration exercise; 2) aerobic exercise combined with high-repetition resistance training; and 3) exercise programs combined with a behavioral-modification component.

Hepatic insulin resistance in obese non-diabetic subjects and in type 2 diabetic patients

OBJECTIVE

Obese non-diabetic patients are characterized by an extra-hepatic insulin resistance. Whether obese patients also have decreased hepatic insulin sensitivity remains controversial.

RESEARCH METHODS AND PROCEDURES

To estimate their hepatic insulin sensitivity, we measured the rate of exogenous insulin infusion required to maintain mildly elevated glycemia in obese patients with type 2 diabetes, obese non-diabetic patients, and lean control subjects during constant infusions of somatostatin and physiological low-glucagon replacement infusions. To account for differences in insulin concentrations among the three groups of subjects, an additional protocol was also performed in healthy lean subjects with higher insulin infusion rates and exogenous dextrose infusion.

RESULTS

The insulin infusion rate required to maintain glycemia at 8.5 mM was increased 4-fold in obese patients with type 2 diabetes and 1.5-fold in obese non-diabetic patients. The net endogenous glucose production (measured with 6,6-(2)H(2)-glucose) and total glucose output (measured with 2-(2)H(1)-glucose) were approximately 30% lower in the patients than in the lean subjects. Net endogenous glucose production and total glucose output were both markedly increased in both groups of obese patients compared with lean control subjects during hyperinsulinemia.

DISCUSSION

Our data indicate that both obese non-diabetic and obese type 2 diabetic patients have a blunted suppressive action of insulin on glucose production, indicating hepatic and renal insulin resistance.