The phrase "to reduce the carbs" means to eat less food that contains carbohydrates. Carbohydrates are a type of nutrient found in foods like bread, pasta, and rice. So, reducing the carbs means cutting back on these types of foods. Full definition
You'll pretty much want to make most of these other reductions by reducing your carb intake rather than protein or fat. (acaloriecounter.com)
By reducing carb calories you'll lose water weight quite quickly. (instantknockout.com)
Basically, the reason why this diet approach works is not because of the varying carb consumption, but because when reducing carb consumption you also reduce total caloric intake. (fitnessandpower.com)