There are hundreds of products on the market and most of them are useless or very expensive. Most of them are based on "science" that is nothing but a marketing scheme.
Many of these products contain "exercise science" which claims that they increase physical performance and strength. The first thing you should ask is what they are used for. The most common types of products are the ones that claim they will help you lose weight or increase endurance. These products have nothing to do with actual physical fitness or the benefits they may bring to your body. Many of them are simply not effective. The most common reason why you are wasting money is because the manufacturer does not properly identify or disclose all the possible effects of the product. For example, when you take a product that says "increase your endurance", it actually increases your heart rate by a factor of 10. The best example is the creatine. The manufacturer has labeled the product "increase your endurance" in the ingredient list. But the creatine is a diuretic, and it raises your blood pressure. It also increases your body temperature. So, how does creatine help you perform better? So the most popular creatine product on the market is creatine monohydrate.