Why can't they feed themselves?

No.

Yes, Rebecca. This bothers me too. Fasting is voluntary  (except for those places where it's legally enforced, or where cultural pressures are heavy). But I don't think it's a time of major deprivation. Daily feasts compensate for daily fasts - but also wreak havoc on blood sugar levels and mental and physical stamina.

Having lived in Kayseri, Turkey, I've had the Ramadan experience: hearing the drummer walk through the streets awakening everyone in time to cook and eat before dawn, smelling the frying eggs at 3:30 am, and witnessing the traffic chaos at 4:30 pm (this was in November) as hordes of hungry people rushed home to eat. The emphasis during Ramadan is on food - not on fasting. 

Also, many people, if possible, just sleep the day away, awakening in the evening to feast, socialize, and conduct business. After a short nap, it's food again, before dawn.

Fasting during daylight hours wouldn't be that hard if one had feasted all night. Going without water though must be difficult, if not dangerous, especially for those who must do physical labour outdoors. Hence, the reversal of the diurnal and the nocturnal - it makes sense under those unnatural circumstances.  But what a tremendous waste of human energy and  efficiency - in countries that can ill afford it. And all to get that "reward."

 Just expanding on what Kinnedar said, about the reversal of the day/ night pattern.

Humans are biologically a diurnal rather than a nocturnal species.  Inventing fire, and then other kinds of lighting, has allowed us to extend the time when we're active; but we still do best, healthwise, with 'early to bed and early to rise'.  We *need* the 'night/ dark' signal to sleep (doing a lot of shift work, involving daytime sleep and then activity by artificial light during the night, has been implicated in a number of hormone-related diseases such as breast cancer).

So the fact that for thirty days Islam completely reverses what is normal and healthy for humans (normal is to sleep - which of course means one is neither drinking nor eating - from sometime not too long after sunset till around sunrise, then be awake, active, drinking and eating as needed, during daylight hours) is just one obvious example of the many, many 'reversals' or what one might call 'anti-nature'/ anti-human  patterns, small and great, that characterise Islam.

It almost looks as if some Muslims use Ramadan as an excuse to guzzle. See Esmerelda's post here about those pizza-and-pepsi deprived Muslims.

The idea of self-control doesn't come into it.