This happens because rapid weight loss can cause you to lose too much fat tissue in the breast area that gives breasts their volume. (mommyedition.com)
Results: Comparing women in the extreme quartiles of adolescent fat intakes, percent dense breast volume (% DBV) was positively associated with saturated fat (mean = 16.4 % vs. 21.5 %; P trend < 0.001). (cebp.aacrjournals.org)
Experimental Physiology (1992), 77, m breast volume changes and the rate of synthesis of human milk using 79 - 87. (bflrc.com)