First of all, bravo to you for having career goal and demonstrating initiative to get there (yes there is hope for the future with young adults like you!). (Standing ovation)
When I was young, I struggled with weight, and not until doing research and finding more recent information which has helped me restore my health and take loads of weight off do I now have a better understanding if why humans pack on the pounds.
There is a mechanism involving insulin that regulates a whole bunch of things in the body, and one thing being your blood sugar. When you eat, for example, a sugary substance, like a glass of chocolate milk, the blood sugar (glucose) level goes up. Your body responds by injecting insulin into your blood, and this triggers the glucose to enter your cells and be converted to fat. Pretty amazing phenomenon. This is why if a kid does nothing but sit down and eat candy (pure sugar substrate) all day, they will grow fatter and fatter. This key fact holds the secret to the fat loss you are seeking.
Many doctors recently have discovered that the way to efficiently lose fat is via paying attention to what causes blood sugar levels rising. In fact, they also discovered that eating a healthy diet that doesn't spike blood sugar also enhances other healthful components in the blood, such as lipids and hormones. This helps you build better, stronger muscles and a healthy cardiovascular system to support it.
The way of eating to do this is called LCHF. Which is low carb, moderate protein and high fat. Google it and you will see info from doctors and researchers at UCLA, Harvard and MIT, amongst other sources and medical institutions.
Again, bravo and good luck in your career and health.
"Your body responds by injecting insulin into your blood, and this triggers the glucose to enter your cells and be converted to fat." I don't mean to nitpick, but you have it just a little off. In reality, the glucose that enters the cells is intended to be used for energy, not to be converted to fat. It's when the glucose isn't used for energy, as in the kid (or adult) who does nothing but sit and eat candy, that the insulin, then shuttles it into fat cells to be stored for later energy. When that kid (or adult) continues to sit around and eat candy (or other simple carbs and processed foods), and never uses any of it for energy, insulin just keeps shuttling the glucose into the fat cells. That's why we have to get up and move so we can use that stored fat as energy.
I meant to commend you for you desire to start losing weight and get healthy again.
Safe weight loss is considered to be 1-2 pounds/week. You've already begun the exercise, now you just have to implement a healthy diet. The one described by Fruttibiscotti is one, there are many others that are healthy and will help you lose weight, as well.
Whatever plan you choose, I agree that you should stick with food that raise your blood sugar the least in order to keep insulin levels lower. Do some research on low glycemic diet. You'll come up with a lot of different foods that you can eat -- mostly veggies, meats, dairy, whole grains (not all are low glycemic), etc.