Do breasts with dense tissue sag less easily?

Breasts sag for a number of reasons:  loss of elasticity and tightness with the aging process, pregnancy and breast feeding, weight gain/loss, BMI, gravity, smoking, no exercise, not wearing supportive bras. Saggy breasts can be corrected with a breast lift and/or reduction. At some point a H breast will require a breast lift.

Thank you for your question! It is hard to tell without examining you.  I suggest you seek a board certified plastic surgeon and get examined and discuss your concerns!  Best of luck!Dhaval Patel 
Double Board Certifed
Plastic Surgeon
Chicago
Hoffman Estates
Oakbrook
Orland Park

Hello! Thank you for your question. Gravity is the primary contributor to breast sagging. Given enough time, heavier breasts are more likely to sag. Keep in mind that if you decide to pursue surgery it’s very important that you find a surgeon whom you are comfortable with and trust and who evaluates you in-person and tailors an individualized treatment plan for you and your aesthetic goals. Best of luck!
Matthew A. DelMauro, M.D.

I think that there are many factors involved when it comes to breasts' propensity for "sagging", medically called breast ptosis. Factors, more important than breast tissue density, include genetic  propensity for skin elasticity loss, history of weight gain/loss, history of pregnancies, aging (time and gravity)… I hope this helps.

Dense breasts usually weight more than fatty breasts and will be subject to the effects of gravity more than fatty breasts.  Sagging occurs for everyone but those with heavier breasts tend to sag more.  Other factors are your skin elasticity and weight gain/loss history.  

To the extent that you are young, the effects of gravity have not yet occurred but are inevitable in H cup breasts.  Your breast reduction is likely to be approved unless macromastia is combined with obesity. Good luck!

Hi and welcome to our forum!
You already answered your question! You aren't sagging because you are young and haven't had any children!
Sagging of the breasts has many causes, including genetic predisposition, breast size, body weight, age, and pregnancy. 
During pregnancy, the glandular elements of the breast enlarge, stretching the overlying skin and soft tissues. If the elasticity of the skin is exceeded, stretch marks will appear, denoting permanent overstretching. The stretched out skin results in breast sag after breast involution following delivery. 
Breast reduction is not primarily performed for sagging. It is a procedure designed to eliminate the symptoms usually associated with large breasts, including neck, shoulder, back pain, bra strap grooving, and chronic rashes beneath the breasts.
Breasts are composed of glandular tissue and fat. Dense breasts weigh more than fatty breasts.
Best wishes...