The average consumer (obviously not you and me) eats 3,747 calories per day. According to the FDA, we should eat 2,000-2,500 calories daily. If everyone ate within those guidelines, the US would significantly lower its energy needs.
Additionally, if we reduced junk food from the current 33% of our collective diet to 10%, we would “double up” on savings, because snacks, sodas, etc. require the highest energy inputs and deliver the most empty calories.
Although “eating locally” has gotten significant press over the past two years, 75% or more of the energy used to get food to the table is consumed in production, not transportation. So eating vegetarian one night per week is estimated to deliver the same energy savings as eating locally 100% of the time.