Exercise, Abdominal Fat, Insulin Resistance
April 12, 2011 by Dr. Marc Darrow, M.D.
Filed under Exercise
Researchers writing in The Journal of Applied Physiology studied 16 obese men and women, about 63 years old, during a 12 week exercise program. During the program the participants exercised 5 days a week for 60 minutes a day (treadmill/cycle ergometry @ 85% of heart rate max). Among the many things the researchers measured was total abdominal fat, subcutaneous fat (fat under the skin) and visceral fat (the fat that surrounds the organs).
From the study abstract: “Exercise improves glucose metabolism and delays the onset and/or reverses insulin resistance in the elderly by an unknown mechanism. In the present study we examined the effects of exercise training on glucose metabolism, abdominal adiposity and adipocytokines* in obese elderly.”
What the researchers found: “Visceral fat loss after aerobic exercise training improves glucose metabolism and is associated with the reversal of insulin resistance in older obese men and women.”
*Adipocytokines are a collective term for secretions from the fat cells that help regulate energy metabolism and food intake among other functions.
Reference: O’Leary VB, Marchetti CM, Krishnan RK, Stetzer BP, Gonzalez F, Kirwan JP. Exercise-induced reversal of Insulin Resistance in Obese Elderly is associated with reduced Visceral Fat.J Appl Physiol (December 22, 2005) Study abstract
Insulin Resistance and Metabolic Syndrome
April 12, 2011 by Dr. Marc Darrow, M.D.
Filed under Insulin
Insulin Resistance Tied To Age-Related Muscle Loss
Writing in the medical journal Diabetes and Metabolism, researchers say: “…insulin resistance could be involved in age-related muscle protein loss, progressively leading to sarcopenia. Therefore in a more general concept, insulin resistance found in many clinical settings, could be considered as a contributor to muscle wasting.”
Insulin Resistence: What Do Some Researchers Say?
When we eat, our bodies release insulin into our blood stream so that we can process glucose (sugars) from our foods to make energy, especially in our muscles. Glucose belongs in our cells and not in our blood. When it remains in our blood we produce more insulin. Increased insulin, according to many researchers, is the number one factor for accelerated aging.
What is the Effect of Insulin Resistance and Loss of Lean Muscle (Sarcopenia) As We Age?
Researchers writing in the Journal of The Federation of American Societies for Experimental Biology say: “A reduced response of older skeletal muscle to anabolic stimuli (exercise & diet) may contribute to the development of sarcopenia. Skeletal muscle protein synthesis is resistant to the anabolic action of insulin in older subjects, which may be an important contributor to the development of sarcopenia.”
Metabolic Syndrome and Stroke
Researchers writing in the Archives of Internal Medicine say that preventing and controlling Metabolic Syndrome is likely to reduce risk of stroke.
Stress at Work and Metabolic Syndrome
Metabolic Syndrome is a combination of symptoms including high blood pressure, abdominal obesity, insulin resistance and others related to coronary heart disease.
What is the Effect of Insulin Resistance and Loss of Lean Muscle (Sarcopenia) As We Age?
April 12, 2011 by Dr. Marc Darrow, M.D.
Filed under Insulin
Sarcopenia – Loss of Lean Muscle
Leucine – An amino acid found in protein rich foods
Researchers writing in the Journal of The Federation of American Societies for Experimental Biology say: “A reduced response of older skeletal muscle to anabolic stimuli (exercise & diet) may contribute to the development of sarcopenia.
Skeletal muscle protein synthesis is resistant to the anabolic action of insulin in older subjects, which may be an important contributor to the development of sarcopenia.”
Writing in Diabetes and Metabolism, French Researchers say:
“Structural and functional modifications occur in skeletal muscle during aging. These defects lead to impairment in muscle strength, contractile capacity and performance.
Among factors implicated in this age-related loss of muscle mass, a dysregulation of protein synthesis and breakdown has frequently been reported.
Insulin plays a major role in regulating muscle protein metabolism, since its action contributes to increase net gain of muscle protein in animal and humans.
Insulin resistance develops with aging, classically involving changes in glucose tolerance. However, the effect of insulin on protein metabolism is less well documented, and insulin resistance could be involved in age-related muscle protein loss, progressively leading to sarcopenia. Therefore in a more general concept, insulin resistance found in many clinical settings, could be considered as a contributor to muscle wasting.”
Insulin Research Articles
April 12, 2011 by Dr. Marc Darrow, M.D.
Filed under Insulin
Insulin and Aging
A new study, to be published, says that high insulin levels, among both diabetics and non-diabetics, may contribute to Alzheimer’s disease.
To quote the authors of the study “Although this model has obvious relevance for diabetes mellitus, hyperinsulinemia and insulin resistance are widespread conditions that affect many nondiabetic adults with obesity, impaired glucose tolerance, cardiovascular disease, and hypertension. Our results provide a cautionary note for the current epidemic of such conditions, which, in the context of an aging population, may provoke a dramatic increase in the prevalence of AD (Alzheimer’s).”
You can read the entire article from the Journal of Neurology
Insulin Resistance Tied To Age-Related Muscle Loss
Writing in the medical journal Diabetes and Metabolism, researchers say: “…insulin resistance could be involved in age-related muscle protein loss, progressively leading to sarcopenia. Therefore in a more general concept, insulin resistance found in many clinical settings, could be considered as a contributor to muscle wasting.”
Guillet C, Boirie Y. Insulin resistance: a contributing factor to age-related muscle mass loss? Diabetes Metab. 2005 Dec;31 Spec No 2:20-6.
Insulin Resistance, Weight Gain Lead to Early Aging
“Tulane University researchers are the first to demonstrate a biological link between insulin resistance, weight gain and signs of early aging in the blood…”
UCSD Study Sheds New Light on Insulin’s Role in Blocking Fat Breakdown in Patients with Type II Diabetes
“Chronically high levels of insulin, as is found in many people with obesity and Type II diabetes, may block specific hormones that trigger energy release into the body, according to researchers at the University of California, San Diego (UCSD) School of Medicine. Their findings, which may point to new approaches to developing improved treatment options for the disease…”
Low Testosterone Levels and Mortality
April 12, 2011 by Dr. Marc Darrow, M.D.
Filed under Testosterone - Men
Researchers writing in the Annals of Internal Medicine examined “whether low testosterone levels are a risk factor for mortality in male veterans.”
Shores MM, Matsumoto AM, Sloan KL, Kivlahan DR. Low serum testosterone and mortality in male veterans.
Arch Intern Med. 2006 Aug 14-28;166(15):1660-5.
BACKGROUND: Low serum testosterone is a common condition in aging associated with decreased muscle mass and insulin resistance. This study evaluated whether low testosterone levels are a risk factor for mortality in male veterans.
METHODS: We used a clinical database to identify men older than 40 years with repeated testosterone levels obtained from October 1, 1994, to December 31, 1999, and without diagnosed prostate cancer. A low testosterone level was a total testosterone level of less than 250 ng/dL (<8.7 nmol/L) or a free testosterone level of less than 0.75 ng/dL (<0.03 nmol/L). Men were classified as having a low testosterone level (166 [19.3%]), an equivocal testosterone level (equal number of low and normal levels) (240 [28.0%]), or a normal testosterone level (452 [52.7%]). The risk for all-cause mortality was estimated using Cox proportional hazards regression models, adjusting for demographic and clinical covariates over a follow-up of up to 8 years. RESULTS: Mortality in men with normal testosterone levels was 20.1% (95% confidence interval [CI], 16.2%-24.1%) vs 24.6% (95% CI, 19.2%-30.0%) in men with equivocal testosterone levels and 34.9% (95% CI, 28.5%-41.4%) in men with low testosterone levels. After adjusting for age, medical morbidity, and other clinical covariates, low testosterone levels continued to be associated with increased mortality (hazard ratio, 1.88; 95% CI, 1.34-2.63; P<.001) while equivocal testosterone levels were not significantly different from normal testosterone levels (hazard ratio, 1.38; 95% CI, 0.99%-1.92%; P=.06). In a sensitivity analysis, men who died within the first year (50 [5.8%]) were excluded to minimize the effect of acute illness, and low testosterone levels continued to be associated with elevated mortality.
CONCLUSIONS: Low testosterone levels were associated with increased mortality in male veterans. Further prospective studies are needed to examine the association between low testosterone levels and mortality.
Testosterone and Reduction in Cardiovascular Risk
April 12, 2011 by Dr. Marc Darrow, M.D.
Filed under Testosterone - Men
Researchers writing in the European Journal of Endocrinology say that “Testosterone replacement therapy reduces insulin resistance and improves glycaemic control in hypogonadal men with type 2 diabetes. Improvements in glycaemic control, insulin resistance, cholesterol and visceral adiposity together represent an overall reduction in cardiovascular risk.”
