Your question is somewhat imprecise, so I will add a bit of precision, so that my answer is valid for the context.

If one removes ALL carbohydrates, the body will enter a state of Ketosis, which means it will burn fat for energy instead of using glucose and glycogen. This of course will increase the amount of fat usage, and typically result in fat weight loss, a typical goal for overweight people who engage in this type of diet.

However, many of the vitamins and minerals needed come from fruit and vegetables, which are primarily carbohydrates, so again if NO carbs are ingested, including fruits and veggies, one would likely incur a vitamin deficiency at some point.

Obviously, complex carb intake can have a net overall positive effect on both weight loss efforts AND maintaining optimum health. Much has been written about such diets so Google "low carb diet" or "no carb diet" and see what comes up. As always, try to use only reputable sites for info.

Hope that helps