The secret to a long and healthy life? Eat less

Totally agree. If you look at the two parallel studies, it seems like diet had a huge effect on the outcome. The NIA study found no significant difference in both groups, and fed the monkeys varied source of protein. The UW study found health improvements in the CR monkeys but fed them 'significantly higher amount of sucrose compared to the NIA diet'.

https://www.nia.nih.gov/newsroom/announcements/2017/01/calor... https://www.ncbi.nlm.nih.gov/pubmed/28094793 https://www.nature.com/articles/ncomms14063

Every time I hear the 'basic physics' or 'first law of thermodynamics' argument in favor of CICO I can't help but remember the joke about 'spherical cows':

"Milk production at a dairy farm was low, so a farmer wrote to the local university to ask for help. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the physicist returned to the farm, and advised the farmer, “I have the solution, but it only works in the case of spherical cows in a vacuum.”

Human beings aren't black boxes, we are living, breathing organisms, and as complex organisms we can process food differently depending on what it is. For example, cows eat grass, and can survive on a diet of 100% grass, so they must get some calories out of it. Otherwise they wouldn't be able to sustain the energy expenditure necessary to power a ~2000 pound beast, and would die early. Humans, on the other hand, cannot digest cellulose, so it will land in your stomach as indigestible fiber after which you will promptly poop it out. If you were to give a human an all grass diet, he/she would die within weeks.

In a similar vein, a calorie of carbs is not digested the same way as a calorie of protein, which is also not digested in the same way as a calorie of fat. For the studies that you mention, I'm certain that the macronutrient composition made very little difference when it comes to weight loss in the short term, but I am far more skeptical about whether a high carb diet is actually sustainable after your body has adjusted to a lower metabolic rate. Most studies of this type show a bounce back in weight after the initial weight loss. Furthermore, it's not and shouldn't be all about weight loss; if a calorie is just a calorie why don't you just eat 1500 calories of pure sucrose per day? Assuming you were able to stick to it, you'll quickly get fatty liver disease, diabetes, and a ton of visceral fat. The idea that the macronutrient composition is irrelevant as long as calorie restriction is maintained is too simplistic a view, and a dangerous one to spread.

This hasn't been popular, or accepted, wisdom for a very long time.

Intermediate fasting (discussed elsewhere in this thread) is much closer to being a modern understanding.

Due to social conditioning, It's not commonly known, but you don't actually need to eat every day. You could lose 10 lbs in just a couple of weeks of not eating any calories, but I would recommend eating 1 lbs of spinach and maybe a combination of other green, red and orange vegetables: that will keep your calorie count under 200 for the day. Drink lots of water.

I know the hunger will drive you crazy in the first few days, but your body gets used to it and it's not so bad, after 3 days.

The first time you do it, perhaps start off with some 16 hour fasts at first for a few months till your used to that, then you can increase it.

This kind of aggressive diet is usually followed by gaining back the weight.