I don't know about the other studies, but I assume they were short-term? I think I remember one of them being only 3 months. That could have been the issue, as

I don't know about the other studies, but I assume they were short-term? I think I remember one of them being only 3 months. That could have been the issue, as I believe calorie restriction leads to a slower metabolic rate. So if you need 2,000 calories, but eat 1,500 for a year, your body should get used to eating 1,500 and maintaining your weight (after losing some initially before it adapts to fewer calories). But I believe intermittent fasting where you eat the same 2,000 calories but just shorten the window of eating to allow your body to crank-up the growth hormone and start autophagy does have long-term benefits, that should lead to prolonged life. And of course, a calorie isn't a calorie. If you eat 200g of net carbs a day, intermittent fasting probably won't prolong your life too much, but it's also going to be more difficult to do IF when you're body is used to having high-levels of blood sugar and insulin in it.