No, it isn't. Unless you're saying you gained weight again while still eating the same diet, you solved the problem, you just failed at implementing the solution.
It's also worth noting that people who have gained a bunch of weight and lost it have a slower metabolism than people who stayed at the same weight. The Hacker's Diet - being based on calories in/calories out - did not account for this factor. The claim it made was that you could lose weight by keeping a calorie deficit for a while, then once you've lost enough weight you could stop the deficit, go back to basically eating at the level you did before and still stay at the new weight. Which doesn't work.
Dieting seems to work because your body takes a long while to adapt to new conditions. Eventually you get hungrier and less active; progress tends to stop and reverse whether or not you keep "trying".
Temporarily losing weight is "a solved problem". But losing weight without reducing metabolism and thereby making yourself more likely to gain weight in the future, is not.
No, it is. Getting people to do it and stick to it is unsolved.
Lifestyle change, to reduce calories and restructure meals to include correct balance of proteins, carbohydrates and fats, and to raise awareness of when food is eaten and how many calories are being eaten, is tricky. But if people do it it works.
12 years ago, I lost 55 pounds in six months. All I had to do was carefully monitor everything I ate and burn 1000+ calories exercising six days a week.
Thing is, that was a solution that worked very well for me when I was self-employed 30-year-old single man. It has not worked at all for me as a 42-year-old married man with a child. I don't have the time for 90 minutes of exercise every day. There is always loads of food around I shouldn't be eating. I have vastly more stress in my life than I had then. And my body very definitely reacts differently to food than it used to.
What I'm trying to say is, I found a great hack for losing weight quickly back in the day. I did not find a solution to keep my weight down in the long term.
...Other than that whatever the formulas are, they seem to make long-term loss nearly impossible for most people.
Can you post a link to this study?
>We don't actually know how TDEE reacts to weight loss in general
I don't think this is something "we don't actually know." Lots of weight loss studies have been done in which energy expenditure has been carefully measured, so there's plenty of data on this.
http://fampra.oxfordjournals.org/content/16/2/196.full
Quote: "...the majority of the studies point to a reduction in short-term resting metabolic rates that is greater than can be explained by the loss of body mass or fat-free mass over the same time period. Unfortunately, there has been very little work done over the last few years regarding the duration of this phenomenon.
[...]
This is relevant for motivated patients who adhere to severe hypocaloric diets to achieve rather large weight losses. When they get to goal weight their metabolic rate is severely depressed, and they can experience almost immediate weight gain if they resume their prior higher calorie intakes. Recent studies have not continued to measure changes in resting metabolic rate for extended periods to determine whether the reductions are self-limiting. "
There's also the "rebound effect", which the Minnesota Starvation Experiment gives us insight into.
People stop dieting and then resume ad libitum eating. They gain fat faster than lean tissue, because gaining fat is easier than gaining lean tissue. Net effect: BF% worsens compared to baseline.
The key is not that "diets don't work, look, they make you fatter"; rather, it's that people see diets as something you do once and then stop. What's actually necessary is ongoing control of food intake.
The parent said he lost 30 pounds over 6 months. This is not a "test case." He implemented the solution effectively. What he ended up doing however was to change the input variables (literally) by increasing the amount he was eating. Therefore the solution he implemented failed, and he gained the weight right back.
(Also, the system I was following (hacker's diet) incorrectly claimed after losing the weight you wouldn't gain it back from simply returning to prior eating habits. Because it didn't account for the now well-known metabolism-lowering effect of dieting.)