I'd go for this one. Which means the one person reduces their food intake by at least double the 5%.
Or possibly the other people in the household see them eating less and follow their example...
What I'd like to know is your last bit - is one quarter of a household eating 25% less on their own, or does "mom" on Ozempic cause "dad and 2 kids" to eat 5% less individually? The former isn't nearly as interesting to me as the latter...