This is based on dietricians' extensive studies that has linked certain brain hormones (ghrelin & leptin: store fat as enegry and control appetite respectively), that 'switch off' when a person enters a no-food dieting phase. Becasue of survival pre-wiring, the brain thinks that the body's famined so it stops burning life-affirming fat and store it to preserve vital organs like the heart, liver and kidneys. In the process, one who goes through long periods of fasting (generally stopping food intake and then eating large quantities of food more than you'd normally do to compensate for lost calories in what's known as the 'fast-feast' theory), becomes fatter instead of thinner!
The solution? It's clinical term is 'grazing', which means to eat separate meals through the day consisting usually of 4-6 mini-meals/ day. There's also a fad that promotes this 'eat more, get thinner' diet that ascribes a EMI (Eat More Index: 4,1 or more=2500 cals/day of low-fat diet), restricted to lo-cal fruit/veggies (called 'heavy food'), that you can eat as much as you want and still keep your weight.