Problem I see with that Minnesota study is since they gave the guys high carb foods that kept their insulin levels up so they could never fat/keto-adapt, they were hormonally forced to burn glucose for fuel. Not getting enough of that due to calorie-restricted diet, they turned to using up their own muscles and organs to convert to glucose to stay alive. A person well adapted hormonally to burning fat for fuel and eating a high fat, moderate protein low carb diet probably could do alright on a lower-ish absolute number of calories compared to someone burning glucose on the same restricted number of calories as mostly carbs. Years ago before discovering low carb I successfully lost a bunch of weight (all gained back plus interest) doing a semi-starvation low fat diet. Constant hunger, pretty unpleasant. Fast forward, lost a similar amount of weight with low carb and intermittent fasting. Hunger during fasting unpleasant, but overall not as unpleasant as previous experience with high carb/low fat, and I have plenty of energy whether I've recently eaten or not, no metabolic slow-down.