They achieved the same longevity in rats by restricting a specific sulfur-containing amino acid (methionine) in their dietary protein consumption.
Ways in which we humans can do that:
1. Eat only plants as animal proteins have high levels of sulfur-containing aminos.
2. Limit protein to 10% calories max.
3. Eat primarily fruits as they have low amounts of sulfur-containing amino acids (by comparison to other plant foods) while still containing enough for human nutritional sufficiency.
All of which we do on 80/10/10.
I've never heard about sugar restriction being a possible cause for rat longevity. But it wouldn't surprise me as rats are supposed to subsists on primarily nuts and seeds which is why they contain 10-15 times the amount of fat burning enzymes compared to humans. So lowering sugar consumption would probably be a good thing for rat physiology.
Glad i'm not a rat.