There isn't much published research on hoodia. Researchers at Brown University in Rhode Island recently found that the steroidal glycosides in hoodia affects nerve cells in the hypothalamus that monitor blood glucose. Simply put, the brain is tricked into thinking there is enough energy (blood sugar) and doesn't need to eat, so it shuts down the hunger mechanism.

In animal studies, hoodia is believed to reduce caloric intake by 30 to 50 percent. There is one human study showing a reduced intake of about 1000 calories per day.

Hoodia works by tricking the brain into thinking it is full. Scientific studies exist on components of Hoodia, indicating that it has direct effects on the central nervous system. There is reported research in which Hoodia may have lowered food intake by a factor of up to fifty percent in both animals and humans. When South African scientists first tested the Hoodia plant, they discovered that the plant contained previous unknown molecules that act on the brain (hypothalamus) to fool the body into thinking that food requirements have been satisfied. This sense of feeling full is due to the brain being tricked into believing that satiety exists. Satiety is a sense of fullness to the point of excess and "to satiate" is to satisfy fully or to excess, in a context most often related to food intake.

Here are some possible effects on the body:
There are no published long-term studies on the safety of hoodia. Just because it has been used for thousands of years doesn't mean it is safe. The San Bushmen are a tribe of hunter-gatherers. They do not take pills for blood pressure, diabetes, cholesterol, depression, and other diseases, like we do. Hoodia simply hasn't reached a wide enough market yet or undergone safety testing to know what the side effects, drug interactions, and safety concerns are, if any.

People with diabetes should be particularly cautious. Because hoodia tricks the brain into thinking that it has enough blood sugar, it's possible that a person's blood sugar could drop dangerously low while taking hoodia. With the regular hunger mechanism turned off, the normal warning signs may be suppressed -- until it's too late.

There are no studies evaluating the use hoodia during pregnancy, lactation, in children, and by people with chronic conditions such as heart, kidney, or liver disease.