It should always be remembered that the weight gain comes in two forms. Firstly there is the weight gain that is seen in healthy individuals. Such weight gain usually comes and goes over time as activity and nutritional habits change, and usually amounts to no more than few pounds at most. Most healthy individuals usually experience such fluctuations in body weight, and this is in fact part of the normal homeostatic mechanisms that allows body weight to fluctuate around a set point. Such weight gain is usually of subcutaneous type and this is not associated with any detrimental effects. Secondly, there is a type of weight gain that is associated with the development of the metabolic syndrome. This type of weight gain is caused by the development of insulin resistance, and is insidious in nature because unlike the fluctuating weight gain in healthy individuals, this weight gain is very difficult to reverse and can lead to other downstream metabolic changes that increase the risk of disease.
Understanding insulin resistance is the key to understanding the weight gain associated with metabolic syndrome. Insulin resistance is a situation whereby the cells of the skeletal muscle and liver become unable to uptake glucose from the blood, and this both raises blood glucose levels and decreases the availability of glucose for energy production in the muscle. The exact mechanism of how insulin resistance occurs is not fully understood, but one line of reasoning suggests that this may be caused by the nutrient overload syndrome. Certain nutrients, particularly refined carbohydrates, are digested too quickly and their absorption rate then exceeds the rate at which the cells can process them. As a result the cells attempt to oxidise (burn) the energy but this leads to the production of free radicals, a byproduct of oxidation. One of the effects of the increase in free radicals is to desensitise the insulin receptor, and in this way the cell protects itself from further energy overload by decreasing glucose uptake.
Free radicals are therefore generated when cells become overloaded with energy, and as a result insulin resistance develops. It should be no surprise therefore that oxidative stress, the term used to describe an over abundance of free radicals, is associated with insulin resistance. In fact oxidative stress is associated with metabolic syndrome, obesity and type 2 diabetes, suggesting that oxidative stress is indeed involved in, or a product of, the insulin resistance that leads to all these conditions. That oxidative stress is involved in the development of weight gain and obesity, perhaps through the development of insulin resistance, intimates that antioxidants would be beneficial at treating insulin resistance. Many studies have investigated the effects of dietary antioxidants on insulin resistance, and many have shown that they are effective at improving the insulin sensitivity of cells and increasing glucose uptake. A diet high in plant based antioxidant, such as the Mediterranean diet, appears to be particularly effective in this regard.
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