Carbs have the effect of making you hungrier, bejeezus. If you take in more than 30g of carbs in any one go (big plate of pasta, chocolates, etc), then your blood sugar will spike rapidly - and then fall just as rapidly, making you hungry.
It's why, if you have a carby breakfast (which most people do have - cereals, toast, etc) you will be ravenous by 11.00, and grab a biscuit (or two!). After lunch - sandwich, crisps, chocolate bar - the same thing will happen, which is why you get the 3.00pm need for something sweet! So you're constantly yo-yoing between too much/too little blood sugar - meaning you're frequently hungry and you're also laying down fat.
The body produces insulin to 'sweep up' the blood sugar, but excess is turned into fat.
If you eat a low carb diet your blood sugar levels are much more stable, and therefore the amount of insulin released is lower and you don't lay down fat.
The biggest advantage, though, is that it acts as an appetite suppressant.
And if your diet is rich in protein, this is also much more satiating than carbohydrate, so you will not feel hungry as quickly.
I can thoroughly recommend this book:
www.amazon.co.uk/Escape-Diet-Trap-John-Briffa/dp/0007442432
It talks about the many myths surrounding dieting/losing weight, in particular the notion that low calorie/low fat is the way to go.