Supplement loading is when you take a higher dosage than normal for a very short period of time and then return to the normal dose for the remainder of the recommended cycle time. Loading periods should be no more than 2-4 days, the remainder of your cycle should be as directed on the supplement packaging.
Loading doesn't necessarily work for everyone. Take creatine for example, higher dosages may actually be a waste of time and money, as an excess of creatine is excreted by the body. The idea is to saturate the muscles with creatine and boost muscle creatine levels by 30-35%. If your levels are already quite high, then after reaching these upper percentages, any excess creatine is useless and therefore excreted as a waste product. - To keep as much creatine in the muscle as possible you should consume plenty of carbs, use Super-Carb.
So the jury is still out on the effectiveness of creatine loading, however it maybe worth trying and monitoring the results to see if it works for you. When loading it maybe wise to take creatine 4-5 times a day, in order to comfortably achieve a 20-25gram dosage.
Giving your body a constant supply of a substance such as creatine will eventually result in the body not producing it naturally. In effect your body is just relying on you to feed it the supplement and becomes idol in the process. As with any exogenous substances including supplements, alcohol and drugs, the body will eventually build up a tolerance and will then require more and more of the substance in order to maintain the desired effect. The results can be detrimental to your health. When you first take creatine for example, the gains you experience are second to none. However, once your body becomes used to the introduction of the creatine, the gains may slowly diminish, leaving you slightly 'deflated' in ego and 'chasing' that initial gain. The answer is not to up your dosage, but rather to cycle the creatine. Cycling is important for any supplement and will allow your body to rest, as well as enabling you to get the most out of your supplements. Effective cycling times may vary for everyone and depends on your body weight, body fat percentage, daily routine and training intensity. Creatine dosages should normally be 0.3gram for every kilo (or 2.2lbs) of body weight.
For nitric oxide enhancers such as arginine alpha ketogluturate, which is a pharmacodynamic, cycling is also important. Pharmacodynamical class drugs are any drug that alters, inhibits or enhances a physiological or biochemical process of the human body.
Thermogenics should also be cycled, as should any supplement that contains ingredients with extreme doses that the average human being would not normally receive from food stuffs alone.