"What are your thoughts on using exercise to contribute to creating a deficit?"
My own personal thoughts are that it's futile at best and incredibly destructive at worst. Calories in / calories out doesn't work like that, a simple math equation where you exercise more and the deficit gets bigger. Your body is a master of weight regulation. If you exercise more (especially dramatically more), you might increase the deficit briefly, but your body counters by burning fewer calories during workouts and at rest, by making you hungrier, by lowering body temperature, by curtailing spontaneous movement, by increasing cravings for high-calorie, high-reward foods.
If weight is all about food, and too much exercise worsens your eating, it becomes an obstacle and not an answer. This is independent of the dietary chaos that occurs with restrictive thinking, guilt, punishment, and the idea of earning your food.
It took me years to untangle food and exercise, and exercise and weight. There were dozens of times I was exposed to the idea that they were separate. I remember talking to Alwyn Cosgrove about why people gain weight during marathon training. There was a study where people added an hour of cardio every day for a year (or something like that) and on average they gained a pound. I remember that video with Craig Ballantyne running on a treadmill while Brad Pilon eats pizza. It was such a vivid illustration of how quickly you can eat thousands of calories and the insane time and effort involved with even making a dent in it through exercise. There was that blogger who lost over 100 pounds and felt that untangling food and exercise was key. There was that post of Georgie's with photos of not exercising for a year. She lost weight. I experienced that myself. I broke my leg and couldn't walk for a couple of months and lost weight so easily it totally blew my mind. My appetite decreased really dramatically. It became far easier to eat less because I wasn't hungry, exhausted, and obsessed with all sugary, carby things. Years later I read The Obesity Code and Health at Every Size. They really hit home why it's not a simple equation where you exercise more and burn more. And of course I read all the non-dieting books and blogs about how restriction and overexercising fuel binges.
I love to exercise. I love to move. I do it every day because it feels amazing. It's fun! IF (big if) I listen to my body and only move in ways that feel good. There are so many benefits to exercise. I do it for the mood boost, strength, flexibility, power, endurance, balance, coordination, confidence, joy, and overall wellbeing. It doesn't have anything to do with weight or food intake.
I realize that if exercise more, my appetite will increase. If I exercise less, it will decrease. So peace is all about finding that happy middle range. I know when I'm there because I'm appropriately hungry for my meals but my appetite is polite and cooperative, not trying to kill me in my sleep. More exercise is not better. Overdoing it makes everything harder and worse.