nolvadex and fat loss :
Nolvadex has estrogenic properties on fat in that it increases lipolisis (fat mobilization). To quote from a couple of studies:
“Tamoxifen, a nonsteroidal antiestrogenic antitumor agent, has weak estrogen-like effects on lipid metabolism, however, the mechanism remains unknown. We previously reported that tamoxifen decreases the activity of lipoprotein lipase (LPL), a key enzyme in triglyceride metabolism, in patients with breast cancer.” (1)
“Treatment of ovariectomized rats with the nonsteroidal antiestrogen tamoxifen mimicked the effects of estradiol and caused significant decreases in food intake and body weight. The decreases in body weight were reflected mainly in a decreased body fat content” (2)
So by acting as an estrogen, it increases lipolysis. This means more fatty acids are released into the blood stream to serve as a POTENTIAL fuel source. Does this mean it causes people to lose weight? Not necessarily. There is a perception that the opposite occurs, but studies have shown this not be the case. Tamoxifen has no significant effect on weight. To quote from yet another study:
“The purpose of this research study was to determine if weight gain is associated with tamoxifen therapy and to observe the impact of weight gain on recurrence and survival. Prognostic indicators, changes in weight, and disease status from diagnosis to the end of treatment were studied in 200 consecutive Stage I and II breast cancer patients, not receiving systemic chemotherapy, admitted from 1986 to the present, with observation periods ranging from 3-5 years. A mean weight gain of 1.2 Kgs was seen in all patients; however, weight gain was not significantly different for those receiving tamoxifen vs. those not receiving tamoxifen, (P = 0.66, CI 95% for the difference -1.8 Kgs to +1.2 Kgs).” (3)
It is interesting to speculate why if nolvadex increases lipolysis it does not lead to weight loss. One possibility is that the subjects, cancer patients, aren’t exercising to take advantage of the mobilized fat. The other possibility is that since nolvadex lowers GH and IGF-1, a reduction in those hormones blunts any potential weight loss.
The fact that Nolvadex increases lipolysis so much is actually a serious problem. The blood stream is flooded with fatty acids that can cause hyperlipidemia. This can cause cardiovascular problems, pancreatitis, fatty liver, and a general accumulation of fat around the organs.
This suggests to me that if you intend to use nolvadex you should have a low fat, high fiber diet to lower the blood lipids, and get plenty of exercise to burn all the fat the nolvadex has mobilized for you. I agree with Dan Duchaine that nolva CAN cause fat loss if you take full advantage of its potential.
(1) Horm Res 2000;53(1):36-9
Tamoxifen inhibits lipoprotein activity: in vivo and in vitro studies.
Hozumi Y, Kawano M, Hakamata Y, Miyata M, Jordan VC.
(2) Am J Physiol 1993 Jun;264(6 Pt 2):R1219-
Tamoxifen mimics the effects of estradiol on food intake, body weight, and body composition in rats.
Wade GN, Heller HW.
(3) Breast Cancer Res Treat 1997 Jun;44(2):135-
Weight gain associated with adjuvant tamoxifen therapy in stage I and II breast cancer: fact or artifact?
Kumar NB, Allen K, Cantor A, Cox CE, Greenberg H, Shah S, Lyman GH.