There are times when an athlete comes to me with the goal making weight under any circumstance and with very short notice. Unfortunately, this happens far more often than it should. If they are not within the percentages and guidelines, I always advise them to reconsider accepting the bout on those terms.
NOTE: The following is for educational purposes and should not be attempted. I list these options because I know that athletes will do whatever it takes to make the weight so the least I can do is help them mitigate risk.
Many athletes do not consider fasting to be an extreme method to make weight and do it all the time. That is usually due to lack of education on the topic. Even if fasting is a common way for athletes to make weight, it isn’t necessary unless under extreme circumstances where a lot of weight must be cut in a very short period of time. Fasting combines both gut content elimination and glycogen depletion. Dry fasting combines both of the above and dehydration via fluid restriction. Fasting should be left to as close as possible to the weigh-in and only under extreme circumstances where the weight cannot be made otherwise. (You should think about other options at this point such as contacting the promotor for a catchweight). One option is to completely fast, the other is to eat only around training when energy is needed. Which one you use depends on the situation. Fasting is not comfortable for most people but may also have health benefits. These health benefits however do not tend to lead to performance benefits.
Glucose is used as the main source of fuel for the cells in the body. Carbohydrates are broken down from the foods we eat and converted into glucose. When glucose isn’t used immediately, it is stored in the liver and muscles as glycogen. Then when the body needs energy and glucose isn’t readily available, glycogen is broken down and used as fuel.
Glycogen causes the body to retain water and 1g of glycogen equates to about 3g of water in the body. This is why when you begin a very low-carb diet that is less than 50g of carbohydrates per day, your body responds by rapidly losing weight. By using normal weight cutting protocols, your glycogen stores should already be slightly depleted due to being on a hypo-caloric diet (much of your carbohydrate intake will go toward bodily functions vs. fully replenishing glycogen stores). When you then incorporate a low-carb diet on top of normal weight cutting protocols, you can expect a very rapid weight decrease. This however does not come without a tradeoff. Go back to the previous chapter and read about “fat adaptation” to see the drawbacks of going on a low-carb diet before a combat sports competition.