You train however many times a week at a weight that you carry every day, a weight that you probably have carried for a long time. Your weight is managed by the output from your training and the input from whatever dietary habits you possess. This regular weight may fluctuate a few pounds here and there, but in general it stays within a certain weight class.
Then a competition comes around. You immediately make your first mistake and cruise the weight classes to see which one you can drop too. You theorize (aka lie) to yourself that if you will be disciplined with eating clean and avoiding pizza and beer, you can have a competitive advantage in a lower weight class. All you have to do is rehydrate, and you will be bigger and stronger than all of your opponents (you forget, which is part of the lie, that your opponents are thinking and planning the same thing you are).
But, as you train and prepare for the comp, you procrastinate with your eating habits. You give yourself silly deadlines – this is the last weekend for wings and nachos – but it isn’t. As you train harder, you get hungrier and continue to eat normally. You just continue to lie to yourself that you can put the diet off a little bit longer.
Now it is a week (or two) before the event, and you realize that its too late to “eat clean” so you make drastic changes. You go buy 5 gallons of distilled water and start peeing out all of your essential minerals. You eat broccoli and lettuce for 6 days and on the 7th, you get a treat of boiled chicken. You fast, or you bloat, or you Dolce. Regardless, you have just sent you body and mind into complete turmoil. You start to obsess over food. You become an asshole (those Snickers commercials are very accurate). You do silly math like a pound of sushi equals a pound of bodyweight, so I can afford to down 1.37 lbs of Tuna this week. Or you get the flu or a cold and actually think that will help lose a pound or two since you the illness has curbed your appetite.
Then the day arrives when you have to layer with sweats or garbage bags and go run off the last few pounds. Maybe you have the luxury of a sauna or you do the salts bath. You spit, piss, and shit every last remaining ounce that you possibly can. All on the sole premise, the belief, the lie, that when you make the weight and you eat again, you will magically get all the powers you had at your original weight back instantaneously.
Here is the ball buster: After you have made weight and eaten that banana, or new fad energy shake, or Denny’s Grand Slam (which is no small shock to your body that now has to divert energy to your digestive system that has to take care of the crap you just ingested. Energy that is probably better suited to be used towards something else, say grappling), the organizers realize there aren’t enough competitors in your division. So, they place you in the weight class with competitors that weighed what you did two weeks ago during your peak of health. Sucks. For. You.
Or bigger ball buster: The comp you were prepping for has same day weigh ins. You invest a good amount of money to go. You even bought a new Gi thinking that its light weight will help you make that lower class. Then you are called to weigh in just before you go onto the mat for your first match. But you miscalculated and you fail to make weight. No second chance to lose it. You are disqualified.
Leave the weight cutting to professionals. They are getting paid to do what they do. For the amateur, eat and train to compete at your natural weight. Don’t endure the misery for something that very likely has no advantage for you even if you believe that it does.