Whenever you diet, you need to eat more nutritiously than a normal person would, because you are eating less. Also, you need more protein, and need to get your essential fatty acids (nuts, some oils, not much though). So instead of doing 60% carbs, 20% fat, 20% protein, you probably should do 50% carbs, 25% fat, 25% protein.
Eat 5 small meals per day, instead of 3 big meals.
Next, you need to exercise every muscle in your body at least once a week, and preferably twice a week. You don't have to do it hard. but just a little bit of a challenge will make the muscle more sensitive to testosterone so you don't lose as much while dieting. Also get 8 hours of sleep and drink enough water.
Being hungry is not fun. Riding an exercise bike before breakfast can accomplish as much in 1 hour as you'd lose all day from eating 75% as much as normal. So definitely do the bike. But that should only make you lose 1 pound per week. To lose another, you need to cut your daily calories by 500 per day. Not fun. I take a steroid and do 2 hours per day when I feel like it, but I don't advise you do that.
Finally, since fat loss is your goal, reducing the amount of muscle burned will mean something else is burned. That is the fat. Taking HMB (a nasty tasting powder you can find on google) before your cardio and before you sleep can reduce how much muscle is lost and thereby make more fat get burned.
BTW, your goal of 45 pounds in 4 months is doable. It is 3 pounds per week. That would be very challenging though. But if you can even get half of that done, that would still be something to be proud off.
One last thing: you can't let holidays and other events be excuses to over eat. It is OK to have a little chocolate now and then, but another thing to eat a lot.
