Well fiber is a carb as well. Pretty sure we NEED it.

Maybe not all the simple carbs we enjoy consuming so much. But complex carbs, yes I think so.
Not all creatures are created equal. Some are more treat motivated than others. I'm a tad overweight... from the MnM's... and from being poor, so having it in the back of my mind that I gotta eat it or it will be gone. Yes some chicken are also mental for whatever reason.
How many times do I hear people say "my chickens are spoiled"? And by that they almost ALWAYS mean they feed excess TREATS.
While this may be true for some people... Doing Atkins back in the day... I nearly gave myself some sort of internal organ failure and had to go to the hospital admitted with a high fever that had been running for a while. I had lost weight (as everybody does) and my blood tests for cholesterol were perfect. My blood sugar (diabetic) was WELL controlled and stayed around 100 constantly. BUT my kidney, liver or something to that effect was malfunctioning. Diets suck and they don't work. I always pigged out after ward to make up for what I wasn't getting during that time. I always gained my weight back. Truly lifestyle matters.
Someone already stated that your friends MUST either be moving more or consuming less calories than they did before even at 4000 calories per day. Weight maintenance is calories in verses calories out period.
Only 2% of feather protein is actually digestible... and I believe feather picking (like over eating) is a behavioral issue *MOST* of the time.
So... can we agree that when we feed a fresh egg it is the 33% protein by caloric content that truly counts.
How many people still think 12% is the number that counts when we are talking how much energy from protein in and egg? Again I have always agreed that is the weight of the protein but not it's ENERGY value.