We are talking about amphibians here, animals that do not produce their own body heat and whose food goes almost entirely towards biomass. In other words, they don't need to eat that much!!!!
I have never seen a problem with an underfed reptile or amphibiaN in captivity, it is ALWAYS a problem with being overfed. Look at this time that you will be gone as a period of fasting that they certainly would encounter quite often in the wild. Do not feed any more than usual. I promise you with absolute 100 percent certainty that your frogs will not feel any ill effects!
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Wildlife dies without a sound, the only voice it has... is yours.
...the oldest task in human history: to live on a piece of land without spoiling it."
Aldo Leopold (1938)
"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
Calvin and Hobbes (Scientific Progress Goes 'Boink', 1991)