Not by themselves.
As we explained on another page, the only factor in weight loss is consuming fewer calories than one needs, regardless of the make up of protein, fat, and carbohydrates. This is true for the inverse - to gain fat, you must consume more calories than you need, regardless of protein, fat, and carbohydrates content.
The process in which carbohydrates are converted into fat deposits is called de novo lipogensis (DNL).
Studies have shown that this process is not easy for the body.[1][2][3][4]
Another study found that eating carbohydrates at night had no negative impact on fat loss.[5]
So while carbohydrates can inhibit fat burning, putting the onus on carbohydrates themselves (instead of excessive calories) as the cause behind fat gain is incorrect.