Does semen have an enzyme that could help with weight loss?

Yes, it is called Zinc Alpha 2 Glycoprotein (ZAG).

Aston University in Birmingham has proven that if administered at a high enough dose (three times per week or more) it triggers a natural process called "Cachexia." This is when a person's body melts their excess fat without diminishing muscle mass.

Swallowing semen to lose weight, in slag is called the "Man Juice Diet" and was coined by Kim Kelly who famously lost weight by eating semen for a month. She went on to become an escort and porn star.

Most recently Pauline Potter, Guinness Book Of Records' "World's Heaviest Woman" lost her crown and more than 100lbs to her "marathon of sex" taking up to seven loads per day.

Swallowing a healthy man's semen more than three times a week also has other great benefits, like literally living longer, 50% reduction in the risk of breast and other cancers, increase in happiness, decrease in depression, better sleep, more daytime energy, clearer skin, lower blood pressure and bowel regularity.