Quite simply, the answer is carb manipulation. It sounds fancier than it is, too. It simply means that you alter how many carbs you eat, and when you eat them. The most basic way to lose fat is to limit the amount of carbs that you eat. For someone who is overweight/obese this will provide significant results. For someone who is already fairly lean and wants to get leaner, this will often leave them feeling like a dog turd sandwich.
For these people, we need to manipulate more about their carbs than just how much they are eating. We need to manipulate the time of consumption as well. I've talked about it before, but by monitoring when we eat carbs we can benefit from the hormonal response to food. Your body will secrete various hormones (insulin, testosterone, growth hormone, leptin, etc) depending on the foods you eat, so we want to take advantage of that. When insulin is released it gives your body the "grow and store" signal, so we want to avoid that as much as possible. Protein and fat will keep your body running anbolically which will help to burn some fat while preserving lean body mass.
This idea of carb manipulation / hormonal response is the basis of some of the more popular diet plans out there today: The Anabolic Diet, Carb Nite, Carb Backloading, Intermittent Fasting and the Warrior Diet. Even the Paleo Diet uses around the idea that by cutting out the majority of (shitty) carbs you will be limiting your insulin response. Fewer carbs at the wrong time and more at the right time and you'll get leaner.
So when is the right time to eat carbs? Fully dependent on your schedule. Kelsi needs to consume a lot more carbs than many people because of her training schedule; she fits in her runs and lifts around her work schedule, and they aren't always back to back. Her energy needs are higher than most, so she needs more carbs throughout the day. Still, she should be aiming to eat them post-training as often as possible.
For most people, I suggest consuming their carbs post-training. If insulin tells your body to "store and grow", then it makes sense that you spike your insulin after you lifted weights and done some damage to your muscles. That way "store and grow" becomes "huge and awesome". Give yourself a 3-4 hour window post-workout to consume the majority of your carbs for the day and then go back to protein, fat and veggies. If you train in the middle of the day, some carbs before bed will help you fall asleep and are ok to have then. Outside of that 3-4 hour period though, you should be consuming mainly protein and fat.
It's not rocket science, just regular science. Eat more carbs and get fatter, eat less carbs and get leaner. Have a great day and go lift some heavy shit!