This is a very complex debate.
To be honest, I think masturbation does not effect you weight directly. There is even some evidence stating that daily* ejectulation can be very healthy. It can be good for mood, nails and hair but also your skin. This is because it realeases endorphins (happy mineral) and helps absorb vitamin E. BUT YOU SHOULD DO THIS ALL IN MODERATION!!!
If you are not already, I strongly suggest that you cut down. (twice a month or better once)
Masturbating too much can have negitive side-effects, such as;
Loss of sex drive
Weaker erections
Slight cases of premature ejectuation
Loss of attraction to prefered sex (gender)
Body swelling (Builds up, but goes away after a week) Taking note, that this is not fat.
WEIGHT FLUCTUATION
Masturbating can lead to high weight fluctuations, it seems to me that you are reciving the low end of the deal. Also taking note, that after a month of quitting your original weight should start to fall back in place.
Ejectuate contains many, many minerals (its actually healthy for you). Unless your eating it again your losing those minerals including testosterone. Testosterone is the male hormone which forms a mans large body mass. If you have noticed your muscle mass decreasing and maybe your voice pitch change, your weight loss may be from shortage of testosterone. If this is the case (and even if it isn't) i suggest you eat lots of zinc (raw brocolli works amazingly but stir-fried is still good... boiled is OK). You could also try eating protein foods like peanuts, fish, kangaroo, eggs and brocolli (again) are great.
ONE LAST THING! SEXUAL INTERCORSE IS DIFFERENT TO "JERKING-OFF" + GO SEE A DOCTOR, WEIGHT LOSS LIKE THAT CAN'T BE GOOD!
Good luck!
*daily: I, myself, still dont trust this statistic.