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Weight Loss and Exercise Differentially Affect Insulin Sensitivity, Body Composition, Cardiorespiratory Fitness, and Muscle Strength in Older Adults With Obesity: A Randomized Controlled Trial.
Brennan, AM, Standley, RA, Anthony, SJ, Grench, KE, Helbling, NL, DeLany, JP, Cornnell, HH, Yi, F, Stefanovic-Racic, M, Toledo, FGS, et al
The journals of gerontology. Series A, Biological sciences and medical sciences. 2022;77(5):1088-1097
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Plain language summary
Aging is marked by increased risk for type 2 diabetes, reduced muscle mass and strength (ie, sarcopenia), decreased physical function and cardiorespiratory fitness, ectopic fat deposition, and insulin resistance all of which increase the risk for physical disability, morbidity, and mortality. These adverse health consequences associated with advanced age are exacerbated with obesity and physical inactivity. The aim of this study was to investigate the effects of weight loss with or without exercise on skeletal muscle insulin sensitivity, exclusively in obese older adults. This study is a 2-site, 6-month randomized controlled trial with a parallel group design. Eighty-six older (60–80 years of age), physically inactive men and women with obesity were randomised into one of the 3 treatments (1:1:1 allocation ratio): control (health education), calorie restriction-induced weight loss, and weight loss with exercise. Results suggest that weight loss via calorie restriction alone is insufficient to significantly improve skeletal muscle insulin sensitivity and requires the addition of exercise to incur benefit, which was also true for clinical measures of insulin resistance including haemoglobin A1C [a blood test that measures the average blood sugar levels over a period of 3 months] and fasting insulin. Authors conclude that regular exercise should be considered as a useful and manageable adjunct to traditional weight loss therapies for older adults with obesity to mitigate risk for chronic disease and maintain functional independence and quality of life.
Abstract
BACKGROUND Aging-related disease risk is exacerbated by obesity and physical inactivity. It is unclear how weight loss and increased activity improve risk in older adults. We aimed to determine the effects of diet-induced weight loss with and without exercise on insulin sensitivity, VO2peak, body composition, and physical function in older obese adults. METHODS Physically inactive older (68.6 ± 4.5 years) obese (body mass index 37.4 ± 4.9 kg/m2) adults were randomized to health education control (HEC; n = 25); diet-induced weight loss (WL; n = 31); or weight loss and exercise (WLEX; n = 28) for 6 months. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, body composition by dual-energy X-ray absorptiometry and MRI, strength by isokinetic dynamometry, and VO2peak by graded exercise test. RESULTS WLEX improved (p < .05) peripheral insulin sensitivity (+75 ± 103%) versus HEC (+12 ± 67%); WL (+36 ± 47%) versus HEC did not reach statistical significance. WLEX increased VO2peak (+7 ± 12%) versus WL (-2 ± 24%) and prevented reductions in strength and lean mass induced by WL (p < .05). WLEX decreased abdominal adipose tissue (-16 ± 9%) versus HEC (-3 ± 8%) and intermuscular adipose tissue (-15 ± 13%) versus both HEC (+9 ± 15%) and WL (+2 ± 11%; p < .01). CONCLUSIONS Exercise with weight loss improved insulin sensitivity and VO2peak, decreased ectopic fat, and preserved lean mass and strength. Weight loss alone decreased lean mass and strength. Older adults intending to lose weight should perform regular exercise to promote cardiometabolic and functional benefits, which may not occur with calorie restriction-induced weight loss alone.
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Interaction Between Type 2 Diabetes Prevention Strategies and Genetic Determinants of Coronary Artery Disease on Cardiometabolic Risk Factors.
Merino, J, Jablonski, KA, Mercader, JM, Kahn, SE, Chen, L, Harden, M, Delahanty, LM, Araneta, MRG, Walford, GA, Jacobs, SBR, et al
Diabetes. 2020;69(1):112-120
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Individual risk of Coronary Artery Disease (CAD) and type 2 diabetes reflects the interplay between lifestyle behaviours acting on a backdrop of genetic predisposition. The aim of this study was to examine whether type 2 diabetes prevention strategies, either an intensive lifestyle intervention (ILS) or metformin treatment (MET), modify the association between CAD genetic risk and cardiometabolic risk factors (CRFs) in participants at high risk of type 2 diabetes. The study is a randomised controlled trial were participants were randomly allocated to one of the three groups; ILS (n = 1,079), MET (850 mg twice daily [n = 1,073]), or placebo (n = 1,082). Results indicate that there weren’t major significant differences in baseline characteristics, except for lower high-density lipoprotein and higher triglyceride in the placebo individuals compared with individuals assigned to MET or ILS. In fact, either an ILS or MET has a beneficial effect on 1-year change in different CRFs. Authors conclude that type 2 diabetes–preventive strategies for individuals at high risk of type 2 diabetes provide beneficial effects on CRFs regardless of CAD genetic risk profile.
Abstract
Coronary artery disease (CAD) is more frequent among individuals with dysglycemia. Preventive interventions for diabetes can improve cardiometabolic risk factors (CRFs), but it is unclear whether the benefits on CRFs are similar for individuals at different genetic risk for CAD. We built a 201-variant polygenic risk score (PRS) for CAD and tested for interaction with diabetes prevention strategies on 1-year changes in CRFs in 2,658 Diabetes Prevention Program (DPP) participants. We also examined whether separate lifestyle behaviors interact with PRS and affect changes in CRFs in each intervention group. Participants in both the lifestyle and metformin interventions had greater improvement in the majority of recognized CRFs compared with placebo (P < 0.001) irrespective of CAD genetic risk (P interaction > 0.05). We detected nominal significant interactions between PRS and dietary quality and physical activity on 1-year change in BMI, fasting glucose, triglycerides, and HDL cholesterol in individuals randomized to metformin or placebo, but none of them achieved the multiple-testing correction for significance. This study confirms that diabetes preventive interventions improve CRFs regardless of CAD genetic risk and delivers hypothesis-generating data on the varying benefit of increasing physical activity and improving diet on intermediate cardiovascular risk factors depending on individual CAD genetic risk profile.