Oxytocin - The "Orgasm Hormone" with Multiple Health Benefits: Increased REE, Decreased Total and Visceral Body Fat, Reduced Appetite and Preserved Bone & Muscle Mass

Oxytocin as fat loss adjuvant? We are not there, yet, but maybe in 5 years.

Classically, oxytocin has been regarded as a polypeptide hormone, produced by the posterior lobe of the pituitary gland, that stimulates contraction of the smooth muscle of the uterus. In fact, oxytocin is yet far more, the mammalian neurohypophysial hormone that is produced in the supraoptic and paraventricular nuclei of the hypothalamus by nerve axons, and stored in the posterior pituitary gland, acts as an important neuromodulator in the brain and plays an important role in the neuroanatomy of intimacy, specifically in sexual reproduction of both sexes.

Over the last decades scientists have begun to investigate oxytocin's role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, and maternal behaviors, the direct effects of oxytocin on muscle, bone, adipose tissue and metabolism, on the other hand, have been discovered only recently.
In a recent study from the University Nice-Sophia Antipolis in Nice, France, for example, injected orchidectomized male mice with 1 mg/kg of OT for 8 weeks to analyze its effect on male steoporosis.

Figure 4: Effects of OT on body weight, muscle weight and fat mass in ORX mice. Sham and ORX mice were submitted to daily injections of OT or Ve for 8 weeks starting 2 weeks after surgery. A) Body and B) muscle weights were measured at the end of treatment. C) The volume of white adipose tissue between lumbar vertebra 1 (L1) and the caudal vertebra 4 (C4) was measured using micro-computed tomography. D, E). Intra-abdominal and sub-cutaneous adipose tissue areas were measured on one section at the L4/L5 (lumbar vertebra 4 and 5) junction level (Beranger. 2015).

The same protocol had previously been used in female mice with success to reverse the bone phenotype (Beranger. 2014), but the analysis of the treated mice demonstrated that OT did not restore the bone loss and muscle atrophy in orchidectomized male mice.
What the provision of oxytocin did do, though, was to reverse the ovariectomy-induced fat mass gain that had also been observed in female mice before. In fact, the provision of 1mg/kg of OT for 8 weeks

• reversed the 50% increase in fat volume due to "castration" (that's only important for "manopause" or men with hypogonadism who are afraid of TRT),
• led to additional decreases in fat mass in sham operated mice (that's important because it would imply that normal men would benefit, as well - not just eunuchs) and
• improved the ratio of subcutenous (="benign") to visceral body fat (that's important for everyone, because a reduced visceral to subcutaneous fat mass ratio is associated with reduced diabetes and CVD risks at the same level of total body fat)