How old are your boys? Healthy adult piggies can weigh anything between 800g and 1500g, the average for pet piggies seems to be about 900g-1300g.
How many pellets do they have? Adult piggies only need about half to a handful per piggy per day (i.e. 10-20g). Reduce the amount gradually if your boys are between 4-14 months old in order to avoid a riot! Pellets should only make about 5% of the daily food intake in an adult piggy's diet.
You can also limit the veg intake to a bowl (ca. 50g) per piggy per day in as many servings as you like.
Feed a pinch of rich readigrass only as an occasional treat.
Guinea pigs have a very fast metabolism, so with a good diet and regular run time their weight will regulate itself.