Your metabolism might increase for a while after a meal. But there's a difference between the metabolism increasing because your body's busy doing the work of converting food into you and your metabolism increasing and giving you more energy for exercise or work. Eat a thanksgiving dinner, and scientists might be able to measure the "thermal effect of food" increasing your energy expenditure. Meanwhile, you're in a food coma on the couch.

I think this is something where your subjective experience counts very much. Lots of people skip the odd meal or two and find that they have more energy, not less. But if you feel better eating something for lunch, go for it.

If you go with the tuna salad, I like spooning stuff like that onto pork rinds.