For example, I have a friend with a very limited sense of smell, so she doesn't really get any enjoyment from food unless it is relatively fatty.
I'm personally not overweight, but if I ever do start getting overweight I'll be in trouble because I've had some medical issues that make it difficult to get my RDI of exercise.
Also don't forget the vast majority of the population has extremely limited information about health. For example, only 6% of parents have even HEARD of the recommendation from the AAP that kids under two shouldn't watch any TV. Not that people should treat the AAP as the absolute source of truth, but if you don't even know what they're saying then clearly you aren't doing your job as a parent.
This isn't just because people are stupid. It's because our media is owned and supported by companies who make physical products. Because of this if Nintendo releases a new videogame system they'll sell millions the first day, and yet by age 18 over 80% of girls haven't gotten enough calcium to prevent osteoporosis. We have great systems for spreading the word about new physical products, at least if they're made by big companies, but our processes for spreading the word about new best practices are virtually non-existent.
By placing blame solely on the individual you're also failing to understand the last 60 years of social science research. The lesson of Milgram, Asch, and many others is that by and large the decisions we make are less than 50% the result of any intrinsic quality or character within ourselves, and are mostly the result of the environments we're surrounded by.
Like 94% of parents (not that I am a parent), I've never heard of that specific AAP recommendation and I don't even know what AAP stands for. I do, however, know that I shouldn't expose my kids to much TV (I'd stick to an hour a day, tops).
Similarly, I don't know off the top of my head how many calories I should be eating. I do know that fusilli with broccoli == good and ravioli with cream sauce == too much. That fat guy with the potato chips knows they are making him fat (even if he doesn't know the exact amount), but he chooses to consume them anyway.
Most likely he also knows he can use the google to learn more information.
That is the statement of the article, nothing else. It doesn't say "obese people cannot be lean" or "diets won't work on obese people." It simple states that obese people are obese 'cause their genes tell them to eat more than they should eat. And that we shouldn't prejudice people because they have 'bad' genes.
No. Unless you cut energy expenditure as well, the energy has to come from somewhere. If you are consuming 1500 Kcal and using 2000 Kcal, you will loose weight. Thermodynamics is not out to get you.
It might be possible to eat less but gain fat, however.
For example, several years ago I wanted to lose weight so I was trying to eat as little as possible and skipping breakfast. My weight stayed mostly constant. Then I decided to start eating breakfast and lost about 10 pounds very quickly. (I know you might think that by skipping breakfast I was eating a bigger lunch, or something like that, but it wasn't the case. I was in college on a very regular schedule, eating the same thing for lunch from the same food truck every day).
I realize this is just one person's anecdotal evidence, but from what I understand this is very common among people who skip breakfast in trying to restrict their caloric intake.
This is why experts recommend eating many small but healthy meals throughout the day, and never skipping out on breakfast.
When all said and done, my personal weight loss method is still eating less: but eating dramatically less then normal for relatively short periods (4-10 weeks). I'm a bit scared to think about everything my body is shutting down in this time. For starters, it takes about a week for my brain to catch up with the changed diet.
However, by far the most common explanation for "I started eating less, counting calories, and I gained weight" is not a tremendous increase in metabolic efficiency, but a combination of:
1) spontaneous fidgeting and unscheduled exercise dropping off (sitting in your chair all day without getting your normal couple trips to the water cooler/bathroom, not shopping today because you're tired) - this is called "NEAT" if you want to Google
2) self-delusion as to the degree of reduced food intake
The latter is the most likely cause of severely failing diets.