Weigh down
Definition 1 of 3
Pro Tip 1/3Physical Weight
Use 'weigh down' to describe objects literally made heavy by something. 
Her backpack was weighed down with books.
Pro Tip 2/3Visibility
'Weigh down' can imply something is visibly sagging or drooping under weight. 
The shelves were weighed down with old records and bowed in the middle.
Pro Tip 3/3Not Always Negative
While it sounds negative, 'weigh down' can be neutral, it depends on context. 
The branches were weighed down with sweet, ripe peaches.