Before low-carb, I averaged 2628kcalories per day, and I gained 5lbs per year on average. So using your theory, (5lbs is 3500x5 kcal divided by 365 days), so I was eating approx 49 extra kcal per day.
Seven weeks ago, I changed to lfhc, and I average 3050kcal per day and I have lost 13.3lbs. So again using your theory (13.3lbs is 3500x13.3 kcal divided by 43 days), so I have been eating approx 1082 to FEW kcal per day.
Are you suggesting that I am burning 1082+49=1131 more calories a day with minimal changes in my activity level? By the way, your argument contradicts itself - if my metabolism was slowing down due to advancing age, I would be gaining even MORE weight.
Like I said, simplistic and outdated CW. Calories in calories out is maybe a starting point at best.
1082 calories for my height and weight:
49min bicycle race without drafting
4hours 20min walking dog
1 hour 5min boxing in the ring
2 hours 10min vigorous weightlifting
I assure you, I have not added this much daily activity by a long shot. I have weight lifted on and off for years (so nothing new here). My job has gotten increasingly sedentary over the years (but I recently made an effort to do more). I bike MUCH less. And, I now walk maybe an hour a week.
Do you think that maybe some foods take more ENERGY than others to digest fully? Or that different states, like ketosis which I am in for example, have different efficiencies? Or that intermittent fasting might change my hormonal balance in a way that helps with fat loss? Or that vitamin D has been shown to help with fat loss? Or that omega 3 has been shown to reduce belly fat? Or that MCT may help with fat loss? Or that saturated fat has been shown to promote fat loss? And that vitamin k has been shown to promote fat loss? Or that protein might be used by the body to repair lean tissue instead of benig used as energy? Or the activation of different enzymes in the body as a response to different foods?
Like I said, there is much more (non-magical things) going on inside a human body than just calories in - calories out.