How can first responders ensure they’re meeting their nutritional needs for high-intensity work while in a calorie deficit?

This can definitely be done but takes some flexibility. To lose weight we need to be in a calorie deficit, but we cannot take that deficit too far or we shut down our metabolism and will not lose weight. For those in an active occupation it is important to fuel adequately for your work. Your provider will calculate your caloric needs based on your level of activity, goal weight, and overall size and body composition.