HCG has been used in bb'ing for a long time and had acquired absolutely zero reputation for aiding fat loss. I had never heard or seen anyone even suggest having an inkling of an impression that it even MAYBE might have been helping them with fat loss.
If one diets in a typical bb'ing manner, there is no reason to say that HCG does anything at all for fat loss in this situation.
However, there are two areas where there likely will or may well be some fat-loss help from HCG.
First, if your dieting method or other circumstances run your testosterone level into the ground, then normalization of testosterone level with HCG would be an aid.
Second, in the case of actually obese individuals there may be an aid. I base this on the statements of a European HCG doctor who states that he sees benefits with HCG only with the obese, and not with the non-obese.
It should be kept in mind that the HCG diet is extreme: only 500 calories per day.
Many individuals who claim success with HCG have no comparison of what their experience is with the same diet and no HCG.
Inasmuch as great claims are made for supposed effects of sublingual HCG with this diet, and with the extreme unlikelihood and absolute lack of evidence of sublingual HCG actually providing significant blood HCG levels, I think it's very likely for the non-obese that the results are attributable entirely to the extreme low calories -- of course a great deal of weight will be lost at 500 cal/day -- with HCG contributing nothing.
If the individual didn't also do the same diet without HCG, then he has no way of concluding that HCG had anything to do with his results.
Last thought: the HCG doctors are all about money. HCG is cheap, and they aren't doing a whole lot of doctoring, but they charge a ransom.