1. You wear the wrong size bra — or a bra at all. Confused? Some studies say that a bra that doesn't provide enough support (read: lots of lift) may cause your boobs to droop over time. So make sure to get the best fit for your body. On the other hand, a 15-year study published in 2013 found that women who never wore a bra actually saw less sagging than women who wore bras. The choice is yours. 2. You don't drink enough water. It's the world's most magical drink for a reason. Skipping water can make your skin appear rough and shrunken, and not just on your face. 3. You don't protect your breasts from the sun. Like to wear tank tops in the summer? Make sure to put some sunscreen on all the skin that will be exposed. Sun damage can cause premature aging and unwanted sagging. 4. You smoke. One eight-year study found that smoking can contribute to sagging. How? It breaks down elastin, which is what gives your skin its youthful appearance. 5. You gain and lose weight — a lot. If you're a yo-yo dieter, your breasts are going to suffer. Your skin loses elasticity when it's stretched. And when you lose weight, the first place you'll slim down is in your boobs because they're mostly fat. Source
