try sex
I imagine sex burns only a small amount of calories for a woman, given that it burns only a small amount for a man (since presumably men burn more than women, most of the time):
"Given that the average bout of sexual activity lasts about 6 minutes, a man in his early-to-mid-30s might expend approximately 21 kcal during sexual intercourse." (
http://www.nejm.org/doi/full/10.1056/NEJMsa1208051)
Now let's say the man is a getbigger and thus lasts, say, 5 times the average length (for a total of 30 minutes). That's still only 105 kcal -- to say nothing of the presumably much smaller amount the woman would burn. Maybe sex is a minimal supplement to weight loss, then, but nothing more -- especially not for a woman.