I am not Muslim, but I was born and raised in a Muslim country, and almost all my friends are Muslim. As you note, in the month of Ramadan, Muslims fast from dawn to dusk. Right before dawn, they eat seheri, and after dusk, they eat iftaar. During the month of Ramadan, no one seems to lose any weight, mainly because everyone seems to overcompensate during iftaar. Where I come from iftaar food is much oilier and richer than the food people usually eat, and also people tend to eat much more during iftaar than they would otherwise. My friends all regularly report gaining weight at the end of Ramadan. This is probably a cultural thing in my country of origin, but from what I have heard, things are same in other Muslim countries.

p.s. Do you mean that your evidence is anecdotal as opposed to empirical?

http://en.wikipedia.org/wiki/Anecdotal_evidence http://en.wikipedia.org/wiki/Empirical_evidence