It is my understanding that Trimspa is Ephedra free it is probably similiar to alot of other products out there such as many of the Weider stackers etc.. Not sure on trimspa but with many of these so called diet fuels you have to stick to a diet and one great side effect is that it speeds up your circulation rate and I have known people that have taken these products and have felt like their heart was going to explode. I have never taken these so called diet fuels but I am heavy into weightlifting and take supplements to cut and maintain, out of all the supplements that I have taken I still feel the MetRX is the best. I have found the best way to use MetRX is to increase your meals to 6 to 8 small meals a day and substitute the MetRX shake for your largest meal, the directions say to take it after working out but I have found that it works better to take before working out. I usually buy the Vanilla MetRX and put the powder in a blender and combine it with Skim milk, yogurt ice cream and fruit (fresh strawberries or bing cherries taste the best) blend it and enjoy.