I just ate a portion of Stouffer's frozen, Five Cheese Lasagna. It costs about $1 per serving. Each serving contains approximately 250 Cal. My gut feel is that the aluminum pan and cover represented at least another 250 Cal per serving. Energy is embedded in growing the food, transporting the food, processing the food, assembling the food, freezing the assembly, putting the assembly into an attractive cardboard coffin, transporting the coffin, keeping the coffin frozen in the store, and cooking the assembly (135 minutes at 400 degrees F). It is probable that 50 Calories were expended for every Calorie that was hoisted upon my fork. That is, the 250 Calories I swallowed required 12,500 Calories to produce and deliver.
One foot on the dock and the other in the canoe
That which cannot be sustained will not be sustained. However, we must all survive the short term.
One thoughtful way to approach this issue is to throw a few dollars at those items and producers who are relatively efficient in terms of Calories-on-fork/Calories-used-to-produce. Throwing a few dollars their way will keep them in business which may turn out to be a very good thing.
Food that looks like its original state and is robust enough to not require special packaging tends to be energy efficient. Apples and other local fruit lead the list. They do not even need to be cooked.
The other end of the spectrum are delicate, perishable unmentionables that must be flown from the far side of the globe. Raspberries in January and South American farm raised salmon come to mind.
The other thing that every consumer can do is to reduce waste. That bell pepper that got moldy in the refrigerator does not represent 100 Calories. It represents 10,000 Calories.
This presents a bit of a dilemma. That Little Debbie yum-yum represents a great deal of embedded energy but it has the shelf life of Egyptian Royalty*. The foods that have the least embedded energy often have shorter shelf lives.
The elegant solution is to be aware. Pay attention. Know what you will eat, and how much. The examined life is well worth living.
*"...shelf life of Egyptian Royalty" term stolen from writer Barbara Kingsolver. She was writing about fresh, in-clove garlic.