Frustrated because, for one thing, this approach is extremely discouraging to people who want to, or are in the process of, losing weight. "Jesus you're so dumb, how can you not understand this one simple thing that you merely have to eat less?"
1. What works/worked for you/your friends/whoever you read about on the internet may not work for everyone. That's because when talking to each other, neither party has the full picture. Neither party knows exactly the level of activity and food habits of the other.
"I simply cut X calories from my diet and it worked!" -- yes, but you also forgot to mention you bike to work and back home every day.
2. Calories in != Calories out. CICO is an approximation, a pretty good one in terms of nutrition, but different foods break down very differently in the body. I recommend watching "Sugar: The Bitter Truth". TLDW: It's a long presentation that talks about how glucose and fructose are broken down by the body.
Furthermore, CICO is super misleading on two levels:
- It completely ignores hunger. Telling someone "Go down to 1400 calories / day" can be a horrible idea if they don't radically change their diet. It's not just about cutting, it's about replacing. There's high-calorie-budget things you can't keep eating/drinking, and low-calorie-budget things that make you feel fuller that have to be introduced.
- Metabolism matters. As I was saying further down in the thread, depending on your metabolism (influenced both by genetics and overall activity level), two people may burn different amounts of energy, both when they're active and even passively by merely existing.
So, for all intents and purposes, yes, calories in == calories out. But that's not the only thing that matters. Get your diet sorted out, get your exercise plan sorted out, find a strategy that works long term (not just a crash diet) and that is and feels comfortable. Anything that is uncomfortable/unpleasant is not something that can be maintained long term.
Also, like the post says, get a digital body scale to start recording your weight. I got a Nokia Health smart scale which gives me graphs of my weight automatically. Being able to see the trends is the most critical tool. Can you imagine getting good performance at load on your servers without instrumentation, merely by just running top once in a while?
PS, if you're downvoting, take the time to leave a comment. All the above is from hard-earned experience.