Hoodia gordonii has no direct effect whatsoever on metabolism. This is a very important statement to make from the beginning. Whoever tries to tell you different must have strong arguments and proof to sustain such statement.

There is no evidence pointing to direct effects of hoodia extract and metabolic rate increase. No scientist can say for sure and give you proof of hoodia's direct effects on catabolism or anabolism. This is very difficult to study as well because obese lab rats have similar but far from identical metabolism as their human counterparts.

One thing is sure, hoodia does indeed help you loose weight. Experience animals can't tell scientists how they feel and this is a major drawback because the action mechanism of hoodia is at hypothalamic level. If you state that hoodia increases metabolic rate you are getting further from the common sense. Take the story of the African bushmen that have been using Hoodia for thousands of years: when going on long hunting trips with scare food reserve they found that when chewing on the flowers of Hoodia gordonii they did not feel so hungry. If metabolic rate would have increased they would have been exhausted even before beginning the chase for the prey... This would be a greater disadvantage compared to appetite suppression.

Good news is that for losing weight hoodia gordonii really helps. The loss of 10-20 extra pounds is by itself is a great tuning of the metabolism. You will feel healthier. Changes in your body will include besides burning fat, muscle atrophy. This is a common effect of weight loss in the beginning because as substances evolve from complex (lipids or proteins) to more simple elements, metabolic pathways also converge, for example the Krebs cycle and after that the oxidative phosphorilation which are common for all catabolic pathways. These are steps in the chain of universal energy: ATP - adenosine triphosphate. This small molecule is like TNT. When needed it can produce great amount of energy all around the cells and tissues of the human body!
            So if you're into weight loss, your body needs to shift from the quickly accessible muscle protein catabolism to the more aesthetic and time consuming fat oxidation. The best way to send this message to your body is to have regular meals because it interprets it like this: I will get another meal in 4 hours so there is no need to store this as fat for later use.