I can imagine it being a lot harder. There are all sorts of arrangements that either enable or reinforce the types/volume of food that you eat. Still, I think people should try to be aware of their own situation and try to identify those factors that promote weight gain. Even if it was harder, I still think it's inappropriate to say it's "basically impossible" and to deny common sense.

You talk about common sense and see a sea of people who are trying to lose weight (cdc says about half of adults in the US[1]) at very low success rates (<1% according to this study [2]) and think: they must be ignorant or not trying hard enough. I just don't really see how you could reasonably make that case.

1. https://www.cdc.gov/nchs/products/databriefs/db313.htm#:~:te....

2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4539812/

I don't really know what to tell you. Again, I understand weight loss can be extremely difficult. What's the conclusion you're trying to get me to accept?

Telling somebody that they're ignorant or not trying hard enough isn't exactly constructive. But neither is digging up studies trying to convince people that they can't achieve some level of fitness. It's science, but somebody else's failure doesn't determine yours. Again, common sense.

You need to examine your life and figure out what factors contribute to your weight gain. Is that already unreasonable?

I don't think the problem is that people don't know what is making them gain weight. If it were, I don't think the rates of obesity would be as high as they are. I'm not saying it's impossible; you've done it, I've done it. I'm saying that at some point you have to have reasonable expectations about what you can expect from people at large .