Although I understand people's eagerness to begin their diet and seeing results as soon as possible there are times people simply are not ready for this and need a diet before their diet. Let me explain...
This happens for one of two reasons -either your current calories are too low and we need time to consistently hit a higher intake level OR your total calories are in check but protein is not so we need to rebalance where those calories come from.
Calories are too low
When someone comes to me hoping to get peeled and show their muscle definition something has to give in terms of the energy balance. If current average calories are too low there is nothing to pull from. We cannot go from 1000 calories per day to 700 it isn not healthy nor sustainable and I will not coach you through that. More exercise isn't always the answer either. Reliance on manually burning calories is a fool's endeavor you will never win. We need to change your metabolism.
In order to begin losing weight we need at least 4 weeks with consistent caloric averages where your body is consuming a sufficient amount of food. Consistently is a key word here. Three days this week, five the next, two the week after that, then back on track with 5 great days... is not going to work. That's 3.75 days/ week hitting your target, 53% accuracy. Not many situations where 53% is considered a passing grade right? Here either. The goal is to hit 5+ days reaching your calorie goal for at least one full month. During this time the goal is increase calories without increasing bodyweight (3-4 pounds maybe but no more than that). If you can successfully do this you can move to the next phase.
Protein is too low
So maybe you're hitting a relatively good number of total calories but your macros are out of balance. You need to consistently achieve a minimum 0.8g of protein per pound of current bodyweight, again 5+ days per week on average for no less that four weeks. Example 160lb person should consume no less than 128g protein. If this is you we may still increase calories ever so slightly again to reset the metabolism.
Regardless which of these categories you may fall in. We will also use this time to begin doing many things to being working on your healthy habits - regularly training in a way that will send a strong hormonal signal to preserve lean mass and burn fat, remove processed foods, cut back on alcohol and other junk, as well as get into a good routine of sleep. Many people will even see the scale begin to move by doing this alone.
But Why?
The idea is we need to regulate blood sugar, hormones, performance, and see adherence before cutting calories or adding more layers only making adherence more challenging. Additionally, this will make future adjustments to the calories and macronutrients more accurate. If our intake levels are all over the place we're really taking a shot in the dark with how your body will react.
This is frustrating for some but a necessary part of the process. One needs to have a long term mindset in order to LOSE FAT AND KEEP IT OFF. If not you, I'm sure someone you know has yo-yo'd up and down with their weight or tried to cut calories and/or increase output by manually burning more only to throw their hands in the air saying, "It just doesn't work for me". I promise it will if you wholeheartedly buy into the process and commit to it for the long haul. Some of the best transformations I have seen took 6-9-12-18 months. Now that is dependent on where they started of course but the point is this is not a fad diet or quick fix. This is a change for a lifetime not just your sister's wedding 2 months from now. I'm sure you would rather lose 10-12lbs by the wedding and keep it off and build on that success than go crazy to lose 30 for the wedding only to end up right back where you are now shortly afterwards.