Irisin is a myokine implicated in lipid and glucose metabolism. The objective of this study is to examine the effect of a body weight reduction on the serum irisin level and physical indicators in obese Japanese patients without diabetes.
The subjects were 22 patients (male/female, 5/17; age, 46.1±16.0 years; body mass index [BMI], 36.9±5.0 kg/m2) who completed a 6-month body weight reduction program at our clinic. The program included diet, exercise therapy and cognitive behavioral therapy. Blood parameters, body composition, exercise tolerance, homeostasis model assessment of insulin resistance (HOMA-IR), and serum irisin were determined before and after intervention, and relationships among changes in these data were examined.
There were significant decreases in body weight and BMI after the intervention. Irisin before the intervention was significantly positively correlated with HOMA-IR (
Body weight reduction did not alter irisin levels. However, irisin may play important roles in fat and glucose metabolism and insulin resistance, and the effects of body weight reduction on irisin kinetics may be a key for obesity treatment.
Citations
It has recently been suggested that skeletal muscle has an important role in insulin resistance in obesity, in addition to exercise tolerance and the fat index. The aim of this study was to identify body composition factors that contribute to improvement of insulin resistance in female patients with obesity who reduce body weight.
We studied 92 female obese patients (age 40.9±10.4 years, body mass index 33.2±4.6 kg/m2) who reduced body weight by ≥5% after an intervention program including diet, exercise therapy, and cognitive behavioral therapy. Before and after the intervention, body composition was evaluated by dual-energy X-ray absorptiometry to examine changes in skeletal muscle mass. Homeostasis model assessment of insulin resistance (HOMA-IR) was measured as an index of insulin resistance. Cardiopulmonary exercise was also performed by all patients.
There were significant improvements in body weight (–10.3%±4.5%), exercise tolerance (anaerobic threshold oxygen uptake 9.1%±18.4%, peak oxygen uptake 11.0%±14.2%), and HOMA-IR (–20.2%±38.3%). Regarding body composition, there were significant decreases in total body fat (–19.3%±9.6%), total fat-free mass (–2.7%±4.3%), and % body fat (–10.1%±7.5%), whereas % skeletal muscle significantly increased (8.9%±7.2%). In stepwise multiple linear regression analysis with change in HOMA-IR as the dependent variable, the change in % skeletal muscle was identified as an independent predictor (β=–0.280,
Improvement of insulin resistance in female obese patients requires maintenance of skeletal muscle mass.
Citations
Changes in Body Composition and FTO Whole Blood DNA Methylation Among Japanese Women: A Randomized Clinical Trial of Weight-Loss Program
Increasing evidence supports an association between age-related loss of muscle mass and insulin resistance. However, the association has not been fully investigated in the general population. Thus, we investigated the association between appendicular skeletal muscle mass (ASM) and insulin resistance in an elderly Korean population.
This cross-sectional study included 158 men (mean age, 71.8) and 241 women (mean age, 70.6) from the Korean Social Life, Health and Aging Project, which started in 2011. In this study, ASM was measured by bioelectrical impedance analysis and was analyzed in three forms: ASM (kg), ASM/height2 (kg/m2), and ASM/weight (%). The homeostasis model assessment of insulin resistance (HOMA-IR) was used as a measure of insulin resistance. The relationships between the ASM values and the HOMA-IR were investigated by multiple linear regression models.
The HOMA-IR was positively associated with ASM (β=0.43,
Our results support the idea that lower skeletal muscle mass is independently associated with insulin resistance in older adults. When evaluating sarcopenia or muscle-related conditions in older adults, their whole body sizes also need to be considered.
Citations
Insulin resistance is related to central obesity and the amount of skeletal muscle. A simple and practical anthropometric marker for muscle mass is not known, although waist circumference (WC) is used as an indicator of abdominal obesity. The aims of this study were to investigate whether arm (AC) and thigh circumferences (TC) can be used as an indicator of muscle mass and if they are related to muscle strength.
A total of 110 obese (body mass index [BMI]≥25 kg/m2) women with type 2 diabetes were enrolled, and WC, AC, and TC were measured. Abdominal visceral fat (AVF), subcutaneous fat (ASF), and total fat (ATF) were assessed by computed tomography, regional muscle (MM), and fat mass by dual-energy X-ray absorptiometry, muscle strength by one repetition maximum (1RM) of both extremities (chest and leg press) and insulin resistance by KITT.
The mean age was 56.2±7.3 years, duration of diabetes was 4.2±4.4 years, and BMI was 27.2±2.8 kg/m2. WC was correlated with ATF, AVF, and ASF (
The muscle mass was related to extremity circumferences, and muscle strength was to extremity/waist circumference ratio in obese women with type 2 diabetes.
Citations
Thigh Circumference and Risk of All-Cause, Cardiovascular and Cerebrovascular Mortality: A Cohort Study