It’s good to give a variety of veg each day, not just one sort. Carrot is high in sugar so will contribute to weight gain.
I feed each of my pigs each day: a small amount of lettuce, a couple of thin slices of pepper, a thin slice of cucumber and a couple of sprigs of a herb such as coriander or dill. I will then add in a small piece of something else like a green bean, a slice of courgette, a small amount of broccoli, a strip of spring greens, a small piece of tomato, some spinach, rocket, etc. Their veg amounts to one cup measure per day.
They each then get a tablespoon of pellets. Unlimited amounts of hay which get refreshed throughout the day.
I only give carrots once every couple of weeks or so and they hardly ever get any fruit.
Do read the feeding guides linked.