I'm not trying to direct this reply to you, but I've been reading various threads across the forum, I've been seeing A LOT of posts just like this one. "No I can't eat as much fat as I want because I tried it for a week and it just makes me fatter! No ________ doesn't work for me because I tried it last month and I got fatter!" It's posts like this that makes me skeptical of some people's dedication and patience when it comes to certain weight loss methods. Fluctuations on the scale are not a direct indication of body fat loss or gain, nor is the scale a representation of your body composition.
However, if your weight goes up day after day; you have a stool every day, and, particularly more than once, and your waistline is getting larger while your lifts are lower or stalling; well, you are over-eating and not gaining new muscule.
I also want to emphasize that people do have different mechanism of satiation, and fat is not universally satiating. Volume, fibre, starches and protein are the other variable in feeling full. It also may change in the same person. I believe that self-experimentation and changing when things are not working (>4 weeks) is important. Faith is good, but we all need positive results.
There are also people whose appetite goes up when they become active, and those who have stable level of appetite independent of the level of activity.
The responses to macros, specific foods, caloric intake and activity levels are very individual. The body structure is individual.
Also, I believe that as person loses weight, appetite and hunger pangs heighten. The experience of someone who is 200 lbs and losing fats and comfortably will be very different when they are at 135 lbs a year later, and their caloric intake has dwindled, their fat cells are screaming to be re-fed, and the athletic ceiling has been reached, hence the intensity of the training cannot be increased by much. That process is likely responsible for weight re-gain that most people who've lost weight experience. I know that I have been fighting this for the past 3 years. And I had only been overweight for ~ 3 years of my life, during pregnancy and afterwards - anyone reading this, take the weight off as soon as you can, do not let it linger! (Sigh) Unfortunately, the only sure way of being consistently lean is probably never getting fat in the first place.
You can be very healthy on small amounts of food. I imagine it is somewhat genetically driven.... and truth be told, I have trouble imagining that at any time until the past maybe 100 years that people had access to 2000 or more calories a day consisently.
External restriction of the calories, the simple lack of food is what keeps people in great shape. Our ideal Ancient Greek athletes came from the environment where the food shortage was so bad that the 60 y.os would take poison at the family feast to lessen the burden, and children were selectively abandoned to death if the family could not feed them by the father's decision.
It's ironic, but yes, a beautiful body as processed by a human mind (and save for Rubence and three of his friends nobody else sincerely considered rolls of fat attractive), is only possible for someone who either has the strength of will to not eat their fill or genetically lower appetite or lives in an environment where the food is in short supply (good food or bad food).