Everything is good in moderation. From the perspective of Taoist Alchemy and TCM, semen is associated with Jing which is lost to an extent with ejaculation. Now, Jing is again of two types. Pre-Natal Jing (Yuan-Jing) is passed on to the fetus from the parents - and is responsible for strength and vitality. This is not associated with sexual fluids and to an extent is also associated with deep meditation, prayer, etc. Post-natal Jing, associated with sexual fluids, is associated with food, air, drinks, etc. These two forms are equally important and complement each other. Post-natal Jing is continually replenished by healthy living and eating and this turn enriches Pre-natal Jing.
If one indulges in excessive sex (determined based upon one’s age and general health), Yin, Jing, and Kidney Qi are reduced, causing chronic fatigue, sore heels, and knees. Also, if one excessively abstains from sex, due to an abnormal increase in Jing (which if not transformed spiritually) can lead to perversions and deviations (as it is said to overflow into the ‘Sea of Marrow’).
The younger and healthier one is, the body’s capacity to replenish this Jing is better! If one ejaculates more than one’s body can handle, as post-natal Jing is not replenished at the rate it is being exhausted, it now starts tapping into Pre-natal Jing, which is very difficult to replenish and affects health, vitality, and longevity. It is not just the process of ejaculation, which of course if the most extreme, but even sexual arousal results in less desirable transformation (Qi - Jing - sexual fluids) where in fact, it is the reverse that one should be aspiring for!
So, in general, sex for most is a very lossy event, more so for men than women, but when the practice is enlightened, it becomes alchemy and hence an energy-neutral or even an energy-positive event (Taoists and Yogins have sexual cultivation and dual/couple cultivation methods for this purpose). For most ordinary folks - an obsessive mind dwelling on this topic - be it attachment or repulsion - is what causes the problem. The Western way has to be to either view sex as profane or sacred, but nothing in between - there is a whole spectrum between these two extremes.
Also, the nature of ejaculation is different for men and women - while men really ejaculate, the women don’t usually lose their secretions. While most men always ejaculate during sex, irrespective of whether the partner experiences orgasm, this disturbance in energetic harmony or give and take makes the loss of Jing pronounced. Women, on the other hand, are strengthened with every orgasm, both of their own and of their male partner. Taoist texts thus prescribe:
- Ages 16 to 25 - masturbation is relatively harmless
- Ages 25 to 30 - reduce the frequency of masturbation
- Ages 30s, 40s, 50s - stop masturbating and conserve sexual fluids for intercourse
When man and woman indulge is connected sex, exchanging body fluids, breathing each other’s breath, both are replenished and rejuvenated. When such a connection is absent, men are depleted. Thus, the prescription of Daoist of yore, Peng-Ze: “A man must conserve his semen during sex. Whenever he does ejaculate, the loss must be compensated by absorbing the essence of the woman’s secretion - which is not possible in the case of masturbation or meaningless/disconnected sex”. During connected sex, the microcosmic orbits of the couple overlap, and magical alchemy occurs when mouth, heart, and genitalia come into physical and energetic contact. For the Daoist, such sex is not necessarily “romantic love” like us in the West would immediately assume, but merely the right level of preparedness as well as the right set of techniques and effort.