It's not the expectation. It's not well understood by people on average (and those dieting) how to mitigate hunger when restricting calories or how to successf

It's not the expectation. It's not well understood by people on average (and those dieting) how to mitigate hunger when restricting calories or how to successfully diet, but they are correct that a deficit is required to lose weight. That's physics and biology. The problem is the knowledge gap leading to strong-willed efforts that can actually backfire. For instance, there's body fat set point theory and metabolic adaptation. The more severe a caloric deficit, and more frequently a person diets, the worse your metabolic outcome. Your body will try to slingshot you back to your "original" weight (the one it's used to), with leptin as a regulator. But if you lose weight slowly, and leverage resistance training, it leads to a better outcome. A prime issue is sustainability. Most people on a diet do succeed in losing weight; it's just that they gain it all back, and they can end up with a worse metabolic rate than they started with, making it that much harder to lose weight again. Metabolic rate can actually recover, but the length for this seems to depend on the severity. Assuming a slow rate of weight loss, it can take almost just as much time as the diet period to recover metabolic rate. For the "Biggest Loser" contestants, it took several years. Leveraging the satiating and thermogenic effects of protein, fiber and resistant starch in diet also helps, for satiety. All of which to say, it's possible to lose weight in a sustainable way without drugs - notwithstanding the failure rate. The people who succeed in doing so are not necessarily "more disciplined", or "less prone to hunger", but they tend to have certain behaviors in common. One of them is exercise (particularly resistance training).