Creatine is a substance based on amino-acid. Naturally it is produced in the human body. Our body produces half of the required endogenously from internal amino acids and the other half is produced from the food we eat. Plenty of Creatine is found in fish and red meat. Creatine is produced by the liver, pancreas and kidneys and is sent to the muscle through the blood. It is then converted into phosphocreatine molecules that store energy in muscular tissues. Creatine increases muscle energy availability. It is done via the ATP cycle. This is the way how cells store and utilize energy. Thus the ATP is available the work we can do. The ability for the body to regenerate ATP also impacts work.
Supplementing with creatine is only intensifying the recycling of ATP. For athletes or weight trainers, this can increase the amount of reps that a person can perform during exercise. The reason for that is that ATP is being restored more quickly. Later these kind of short term improvements in training can transform into longer-term strength and (increased muscle mass.) Thus if the person is not working out in conjunction with creatine supplemention, it means that money are just being down the drain but by no means you will get any weight gain. Creatine isn’t a substance that gives a person muscle - it actually allows working harder in the gym. And only on this way to get more muscle and therefore weight gain.
Some people claim gaining weight as a result of taking creatine. This weight gain is usually a combination of some lean muscle mass with increased intramuscular water retention. It’s not fat gain as a result of creatine supplementation.
Zero benefit to creatine supplementation if you are not working out hard along with it. That said, it won’t make you fat either, although it could make you gain some water weight.