Adiponectin is secreted by adipose cells and mimics many metabolic actions of insulin. However, mechanisms by which adiponectin acts are poorly understood. The vascular action of insulin to stimulate endothelial production of nitric oxide (NO), leading to vasodilation and increased blood flow is an important component of insulin-stimulated whole body glucose utilization. Therefore, we hypothesized that adiponectin may also stimulate production of NO in endothelium.
We conclude that adiponectin has novel vascular actions to directly stimulate production of NO in endothelial cells using phosphatidylinositol 3-kinase-dependent pathways involving phosphorylation of eNOS at Ser1179 by AMPK. Thus, the effects of adiponectin to augment metabolic actions of insulin in vivo may be due, in part, to vasodilator actions of adiponectin.
It is a simple fact that the fat stored in the wrong parts of the body (inside the liver and pancreas)
is used up first when the body has to rely upon its own stores of fat to burn. Any pattern of eating which brings about substantial weight loss over a period of time will be effective.
Body weight loss increases plasma and adipose tissue concentrations of potentially toxic pollutants in obese individuals.
AuthorsChevrier, J.; Dewailly, É.; Ayotte, P.; Mauriège, P.; Després, J. P.; Tremblay, A.
JournalInternational Journal of Obesity 2000 Vol. 24 No. 10 pp. 1272-1278
While there appears to be a consensus among scientists and clinicians that body weight loss reduces the risk of several chronic diseases, these apparently favourable effects be balanced against any potentially harmful side effect of weight loss. In this regard, weight loss has been shown to produce an increase in blood concentration of potentially toxic organochlorine pollutants in animals that can cause prejudice to health, but human data are lacking. 39 obese individuals were subjected to a hypo-energy diet over 15 weeks. Blood and subcutaneous adipose tissue samples were analysed before and after treatment for 26 organochlorine compounds. A control group consisting of 57 women of similar mean age was also formed in order to compare plasma concentrations. Organochlorine pollutants were found in every subject and all 19 compounds detected had their plasma concentration increased following treatment (mean body weight loss 9.5 kg), 15 of which were significant. When compared with a control group, 5 compounds increased significantly. These observations persisted after an 18 week low-fat diet/exercise programme follow-up. Increases were correlated with body weight loss (-0.3≥r≥-0.6, P<0.05) and adipose tissue analyses yielded similar results, as their concentration of organochlorine compounds increased following treatment. Body weight loss increases plasma and subcutaneous adipose tissue concentrations of organochlorine pesticides and PCBs in obese subjects. These results raise concerns about an undesired and potentially harmful side effect of weight loss in some obese patients who seem to be at greater risk of health problems than leaner subjects since they show higher organochlorine body burden.
One of the links between fasting and longevity seems to be a hormone called insulin-like growth factor 1 (IGF-1). As Prof Longo explained, IGF-1 and other growth factors keep our cells constantly active. It’s like driving along with your foot hard on the accelerator pedal.
You need adequate levels of IGF-1 and other growth factors when you are growing, but high levels later in life appear to lead to accelerated ageing. The evidence for this comes not just from animals such as the Laron mice, genetically engineered so that they don’t respond to IGF-1, but also from humans.
Prof Longo has studied certain villagers in Ecuador who have a genetic defect called Laron syndrome. It is incredibly rare: fewer than 350 people worldwide are known to have the condition. Like the mice, people with Laron syndrome don’t respond to IGF-1. They are short, typically less than 4ft tall, with prominent foreheads and underdeveloped jaws.
Most surprisingly, as Prof Longo explained, they appear immune to cancer: “There are no reports, not a single one, of them ever dying of cancer, yet their relatives in the same household, the same age, get cancer like everybody else.”
Fasting lowers levels of IGF-1 and also appears to switch on a number of DNA repair genes. The reason seems to be that when we run out of food our bodies change from “growth” to “repair” mode. But Prof Longo warned me that fasting is not for the faint-hearted, and is safest done in a specialised centre or under supervision.
“There’s going to be a drop in blood pressure, a drop in glucose levels and metabolic reprogramming,” he said. “Some people faint. It’s not common but it happens.”
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