The key to any sustained weight loss (vs. temporary weight loss) is that you make long-term diet changes. So if you decide that you are not going to eat grain/wheat/bread again and stick to that then anyw eight loss would be long-term. If you do it as a short-term fix you'll likely gain back whatever you might lose.
It is actually not that hard to cut sugar if you cut the refined stuff too - they feed each other in terms of cravings. BUT if you cut those out you have to add in more fat (healthy fat that fills you up) and more protein or you'll wind up hungry all the time. So add extra butter to your food, eat full fat yogurt, etc... at the same time you remove the starchy stuff from your diet.
Mom of 4: Boy (10), Girl (7), Boy (4), Girl (2)