You can't underestimate the psychological importance of tricking yourself into eating fewer calories. Carbohydrates are very calorie dense, and high-carb foods are usually psychologically less satisfying than foods you would eat on a ketogenic diet. A plain bagel has about as many calories as a 7 oz new york strip. Which would you rather have for lunch?
I'm assuming you are not a mid or long distance runner, though.
If you talk to many runners, myself included, we really do crave carbs. Because our bodies need it for the distance we're running.
As a mid-distance runner, proteins are good, but I use them up as energy very, very fast (even when I'm not running), so I get hungry faster if I only eat protein.
Yes, it does depend. That said, I think the intersection of the set of people looking to lose weight and the set of medium/long-distance runners is nearly nil...
I think for your typical person, who is typically somewhat overweight, low-carb and ketogenic diets are a good way to go. People tend to eat what they grew up eating, and western cuisine is the product of historical contexts in which grain was cheap and meat/fat was expensive. A lot of typical food is thus based on flavoring-up bland bread with spare amounts of flavorful meat and fat. But that's not really relevant to people these days. You can get a lot of the flavor and filling quality of meat and fat without the extra calories from the carbs.
E.g. most of the calories in a fajita comes from the tortilla. Most people on a diet might cut net calories by eating half a fajita. Now they're just hungry. I'd rather eat an extra-big portion of the filling out of fajita, maybe with some cheese crumbled on top, and cut calories by getting rid of the least flavorful part of the meal. Again, this won't work for everyone, but I think it's a good "go to" default for typical people.
