i'm no dietitian but i had to take nutrition in college, and i've got a few friends who are personal trainers or went into the medical field. for your work out, try to set aside a good 20 minutes of cardio in which you get your heart rate up. while going and doing a ton of crunches and core might seem the right way to go, you should hold off for the first month or two, the ab muscles will grow under the fat, and might make it appear like you gained weight as a result.
in terms of food, as mentioned above, no sweets, pop, or other empty calories. while bread and pasta can make you gain weight, it's the sugars you should avoid more than the carbs. try to eat a meal with wild rice instead of noodles, and do your best to not slather sauces all over it. a trick is to use a lunch plate instead of a dinner plate to help with portion size [which your portions are very important] one piece of chicken or fish [red meat once a week is fine as long as it's not a giant steak. go for one the size of a deck of playing cards or the palm of your hand] then load the rest of the plate with veggies and some rice [if you want a starch that is] also, don't avoid fat, our bodies does need some, just eat good fats, and avoid trans fats. so avocado is a good thing to eat.
in regards to your magickal help, i did post a spell that works for e and my friends, it won't make you loose all the weight instantly, but it will help you with your cravings and make you eat good foods. myself and a few of my friends have noticed we get a headache if we eat 'junk food' after casting the spell, while a few friends will get nauseous. not sure if you count that as a plus though, it only works for one month, so you need to recast it until you don't need it anymore.
one final thing, you should keep a food journal. write down everything you eat or drink throughout the day [and size or calories if you know it] plus your work out. what i find helpful is to write motivators or fun little facts to help you focus on why you're doing this instead of becoming a slave to your diet. even if it's little things like 'i didn't buy a bag of chips today', 'ran upstairs and wasn't winded' or funny little somethings [for example from mine 'someone wrote on the steps to the gym 'you go girl. work it, then have a cheeseburger' made me laugh. but now i want an avocado and cheese burger.']