As someone has pointed out above, it seems like the calorie restriction is not really the reason for improved health. The real reason seems to be that reducing calories happens to also reduce all the stuff that makes us sick in the first place, like pro-inflammatory vegetable oils, sugar, and refined carbohydrates. If you look at the actual studies mentioned in the article, you'll see that the NIA study didn't find any difference between the two groups of monkeys, while the UW study did. The primary difference between the two is that the NIA fed the monkeys varied protein sources, while the UW study fed them significantly higher levels of sucrose. We already know that sugar is bad for you, so it makes sense that reducing its intake would improve health. The CR is a red herring.
I also checked some of the iDiet recipes, and I'm pretty sure they will do you more harm than good. Margarine, like pretty much any vegetable oil other than olive/avocado/coconut, is really bad for you. Egg yolks are not bad for you at all and I wouldn't worry about cholesterol in food (this is a whole topic in and of itself that I won't really go into here). One of the recipes on there is oatmeal with maple syrup; that is just sugar and grains, which honestly just feels like a slightly healthier frosted flakes.
Do you have sources for that? Which vegetables oils are healthy and which are unhealthy and why?
The only relevant knowledge I have is that saturated and trans fats are bad and that unsaturated are good. One source for that is for example https://www.hsph.harvard.edu/nutritionsource/what-should-you... .
If this is what you are refering to then margarine is indeed bad because it often contains high amounts of trans fat but for example coconut oil isnt good either for its high saturated fat content. Plenty of other vegetable oils should be fine judging by their fat contents rather than "really bad".