What should I do when weight jumps after more carbs?
First, do not panic. More carbs can refill glycogen, and glycogen is stored with water. A fast 1-5 pound jump after a higher-carb or higher-sodium day is usually mostly fluid and food mass, not new fat.
Stay consistent for several days and compare averages. Fat gain requires a meaningful calorie surplus over time. If calories were controlled, the scale spike is information about water balance, not evidence that carbs are incompatible with your body.