Counting calories works on a thermodynamics level, not a human level.

The real problem is hormones.

This is why drugs pike glp1 work. Is not burning more calories, it's making people eat less. This makes people lose weight. But it's not a cure, in fact it's a bandaid that will fail the way it's being used, and the data already supports this. People on glp gain the weight back after use, or even continue use after 2 years.

The problem is insulin. The more blood sugar spikes we get the more insulin we produce and the more weight we gain. This isn't a much of a problem in younger humans, but after a while, other hormones like estrogen and testosterone get stored in the fat as well. This causes a ton of problems.

Is we attack the hormone issue, people lose weight. One of the easiest way is installing a blood sugar monitor and linking it to your phone. Cut out food that spikes insulin and maintaining a calorie intake to match bmr gets easy.

Is we continue to tell people to count calories, we will continue to fail like we have for the past 30 years of this epidemic because will power is a finite resource that gets burned up.

Another thing we find with the calories in calories out equation is reducing calories for a long period also reduces calories out. Say we reduce 200 calories from 2000 to 1800, in the long run our bmr goes to 1800 with the same macro ratios.

The math is absolute for body weight, but isn't absolute is the humans ability to maintain the diet, hence why people fail.

The other think to consider for macro is body composition. Two people can eat 2500 calories day for long periods and have two completely different body types. One will be fat, and one will be ripped. This is due to insulin storing energy, and one might have higher ketone levels and gain more muscle leading to different bmr outputs.

For body builders or underweight people, they find it's incredibly hard to gain weight,due to trying to power though high satiation levels, while some people gain fat when at a 1800 calorie diet, and they feel incredibly hungry so day. The difference is the insulin levels.

We can see this is humans with diabetes type 1, it's near impossible for those people to gain weight no matter what they eat. Is because the human body can't store energy without insulin. A couple of doctors are even say using insulin in type 2 diabetes are the worse thing we are doing, because it causes the problem to become worse. They are now putting blood sugar monitor on these patients and looking to limit insulin spikes and some have even reversed their diabetes completely. Patients that receive insulin as part of there condition almost never reverse their condition.