This goes back about 20 years, but I spent a couple of days with a professional wrestler who shared about when his was on his way up in the business, and money was very tight. He was getting by on a nasty mix of canned tuna and concentrated orange juice. High in protein, high in vitamins - is was a low cost, high impact meal.
I don't know that I could stomach such a meal, but it does make good sense if you are needing those kind of calories. Of course you would need refrigeration for the OJ concentrate and this might not be realistic depending upon the situation.
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While I have long believed that I will never get old, I have come to the realization that sooner or later there will be more people younger than me.