mobilize free fatty acids (FFA) for burning when activated. Additionally, the stimulation of B-2
receptors seem to help prevent muscle wasting during dieting. B-3 receptors are found primarily
in brown adipose tissue (BAT, see below for details) and are also involved in calorie burning.
Overall, the activation of beta-receptors tends to accelerate certain processes in the body
including heart rate, blood pressure, calorie burning, heat generation and fat breakdown (1). In a
sense they can be thought of as ‘accelerators’ similar to the one in a car. Therefore, substances
which stimulate beta-receptors will increase these processes. Although there are numerous
beta-agonists, the most commonly known one is ephedrine, which is discussed shortly.
There are two types of alpha receptors: alpha-1 and alpha-2. A-1 receptors are found
primarily in the heart while a-2 receptors occur primarily in fat cells. When stimulated, A-2
receptors inhibit FFA mobilization (2,3) making them a ‘bad’ receptor from a fat loss point of
view. Additionally, research has found that body fat in women’s legs and buttocks has a
preponderance of a-2 receptors compared to b-2 receptors (4-6). It is not uncommon to see
women whose upper body is very lean, but whose lower body still appears fat. This may be
partially explained by differences in receptor density.
Overall, the activation of alpha receptors tends to slow certain processes in the body
including heart rate, blood pressure, calorie burning and fat breakdown. In a sense they can be
thought of as ‘brakes’ similar to those in a car. Since alpha receptors inhibit fat mobilization, a
substance which inhibits these receptors will increase fat mobilization (2). By inhibiting the
inhibitors, the overall response is an increase. The primary substance which can be used to
inhibit alpha-receptors is an herb called yohimbe, discussed below.
Brown adipose tissue (BAT) and white adipose tissue (WAT)
There are two different types of adipose tissue in the body. White adipose tissue (WAT) is
the primary storage site for bodyfat, containing mostly stored triglycerides, some water, and a
few mitochondria (which are used to burn fat for energy). In contrast, brown adipose tissue
(BAT) contains little triglyceride but relatively more mitochondria (7). This makes BAT a type of
fat which burns FFA generating heat in the process.
Initially, humans were not thought to have much BAT but recent research documents its
existence, primarily in the back of the neck and between the ribs (7). Some research has
suggested that BAT, like any other tissue, can grow larger if chronically stimulated by such
things as ephedrine, cold, etc (8). An increase in BAT would increase the thermogenic response
(amount of calories burned) to those same stimuli.
Section 2: Ephedrine and related compounds
Probably the most common, and perhaps the most effective, fat loss compound currently
available over the counter is ephedrine, also known by its herbal name MaHuang. Ephedrine is
sold as asthma medication and is known as a non-specific beta-agonist, meaning that it
stimulates the all of the beta-receptors to one degree or another.