There's a hormonal component to weight loss. Some people literally do not get a reliable "I'm full, stop eating" signal from their bodies. For other people, eating is stress response. (Sometimes one becomes the other.)
If your body is telling you 24/7 that you're hungry, it's very hard to ignore that drive - it's literally one of our most basic hardwired instincts. Even more so if you have a particularly stressful life or get poor sleep, which also feeds into the hormone issues.
So yes, it is always "calories in - calories out"... but unless you're willing to lock people in a lab and have a third-party control the diet, you also have to consider the mental and biological factors that drive how many calories people's bodies are seeking out.
Diet and exercise do work for some people, and is always the best option when it works. But we also know from decades of failed diets that they do not work for many people - lifestyle modification has a terrible success rate.
If your body is telling you 24/7 that you're hungry, it's very hard to ignore that drive - it's literally one of our most basic hardwired instincts. Even more so if you have a particularly stressful life or get poor sleep, which also feeds into the hormone issues.
So yes, it is always "calories in - calories out"... but unless you're willing to lock people in a lab and have a third-party control the diet, you also have to consider the mental and biological factors that drive how many calories people's bodies are seeking out.
Diet and exercise do work for some people, and is always the best option when it works. But we also know from decades of failed diets that they do not work for many people - lifestyle modification has a terrible success rate.