by Daniel Gwartney, M.D.
Losing bodyfat is one of a bodybuilder's main goals—and possibly the most frustrating. After long periods of dieting you often hit a plateau. What happens when fat loss comes to a screeching halt? You redouble your efforts. You fumble around with your diet, supplements, cardio and so on, trying to increase your caloric expenditure and metabolic rate.
Despite the best intentions, however, many of those efforts are self-defeating. People who are trying to lose weight often experience a decrease in basal metabolic rate, or BMR, which is the number of calories you burn at rest. The frustrating part is that it happens following long periods of low-calo-rie dieting; stimulant use, including ephedra and caffeine; and excessive physical activity. Do any of those scenarios sound familiar?
The decrease in BMR is directly related to the level of thyroid hormone activity, which refers to the levels of two hormones released by the thyroid gland, thyroxine, or T4, and triiodothyronine, or T3. T4 is a low-activity thyroid hormone, and T3 is a highly active one. The overall thyroid hormone activity involves the total amount of thyroid hormones and their relative proportions. Optimal thyroid activity depends on necessary levels of the hormones and the rate of conversion of T4 to T3.
Most thyroid hormone is released in the form of T4 and needs to be converted to T3, a process that takes place in the liver and is regulated by caloric intake, rather than caloric expenditure. In simple terms, if you are bringing in lots of fuel—i.e., food—you can turn up the heat, literally and figuratively. If, however, you aren't bringing in enough calories, your body turns its thermostat down and you burn fewer calories. It makes sense, especially if you think of long-term survival.
Some products have been shown to be effective, including essential fatty acids, soy-protein isolates and the use of low-glycemic-index carbohydrates. New, theoretically thermogenic combinations are being introduced almost daily, including such agents as yohimbine, tyrosine and phenylalanine. Typically, they are added to ECA or a chemically related compound like synephrine or pseu-doephedrine, so we may end up seeing the same problems.
All of those products, with the exception of soy-protein isolates, interfere with thyroid activity. That fact led to the development of Thyro Stak. It includes five ingredients that have been shown to support or enhance thyroid activity even in low-calorie environments.
The main ingredient is an herb that has received little attention in Western medicine, though it's been used in Ayurvedic medicine for many centuries. Commiphora mukul contains a class of active compounds known as guggulsterones,12.34.5,6 and, while there isn't a great deal of published research on the compounds, what there is indicates that guggulsterones, specifically guggulsterones Z and E, have thyroid-stimulating activity.5 6 Subjects in those studies showed an increase in thyroid hormone levels and an increase in the conversion of T4 to T3. They showed lower cholesterol and blood triglyceride levels as well, further indicating increased thyroid activity.
Thyro Stak also contains phosphates, which are found in such high-energy compounds as ATP and phosphocreatine. Thyroid activity is closely linked to the amount of energy you have, so it's a good idea for everyone to take an ample amount of phosphates daily. Numerous studies have shown the effect of phosphate supplementation on metabolic rate. Of particular interest is a study published in 1996, which demonstrated that phosphates can pre-
vent a decrease in T3 and an increase in resting metabolism in subjects who are on low-energy diets.7 That, in addition to phosphates' positive effects on creatine storage, buffering lactic acid and increasing ATP, firmly establishes the value of including phosphates in Thyro Stak.
The product contains niacin, selenium and magnesium. Niacin plays a role in supporting the co-factors necessary for energy production, such as NAD(H) and NADP(H). More than 200 enzymes require NAD and NADP. NAD is involved in energy production, while NADP(H) is
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