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Exercise, Irisin & Fat loss

June 4, 2012

Researchers at the Dana-Farber Cancer Institute have identified a hormone in muscle which may be responsible for the health benefits of exercise.

Irisin also ameliorates glucose tolerance and can affect insulin levels which may be useful in the treatment of diabetes.

Brown fat  seems to play a major role in maintaining normal weight. One study found that the more brown fat a person has, the lower their Body Mass Index (a measure of overall fat levels) is. In animal study  a genetic abnormality which eliminated brown fat showed that  obesity levels are higher even without overeating.

In infants, brown fat is an important regulator of body temperature, helping to keep the infant warm. Unlike white fat, when brown fat is metabolized (burned), most of its energy content is converted into heat. Adults don’t seem to need this system of keeping warm.

The studies at the Dana-Farber Institute focussed on injecting irisin into the muscles of sedentary adult mice that were both obese and pre-diabetic. Within 10 days of treatment, the mice showed better control of blood sugar and insulin levels and also lost a small amount of weight. The researchers suspect that longer therapy would have led to greater weight loss.

Exercise releases irisin, which exits the muscle cell and carries its message to other cells of the body. Ultimately, some white fat cells are told to convert to brown fat cells and islet cells of the pancreas are told to produce more insulin.

“The key message for anyone wanting to control weight, cholesterol levels and to prevent chronic conditions like Diabetes is that exercise should play an integral part of a wider healthy lifestyle strategy.  Diet will help to complement a healthy lifestyle and functional drinks like InnOrbit’s UP&GO can support your exercise programme.” Dr A. Ward (InnOrbit)


From Jorge Iván Castillo-Quan: “A well-described effect of exercise is ‘browning’ of white adipose tissue (WAT) – that is, exercise increases the relative amount of brown adipose tissue (BAT). In contrast to the primarily fat-storing function of WAT, BAT has non-shivering thermogenic properties owing to expression of uncoupling protein-1 (UCP1) and increased mitochondrial content. In addition, higher BAT levels are associated with resistance to metabolic diseases. Induction of a browning programme in rodents reduces body weight and improves glucose homeostasis.  Although it was previously thought that, in humans, BAT regresses with age to an almost non-existent brown depot in adults, recent evidence has proven otherwise. Importantly, however, it has been shown that the amount of BAT is significantly lower in overweight or obese subjects, and that there is a negative relationship between BAT and both body mass index and percentage of body fat. Therefore, it is clear that Brown Adipose Tissue is both present and functional in adult humans, and that lower amounts of BAT are associated with obesity. An exciting new study from the Spiegelman laboratory has now uncovered a molecular mechanism by which exercise-induced browning can occur, involving a newly identified PGC-1α-induced myokine.”

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