[HyperSane]

"I know you're really attached to the energy imbalance theory of obesity. "

It isn't a theory, it is a fact. It is basic thermodynamics. The human body requires a constant amount of energy for basic operation and activity. Any excess is stored as fat for future use. Creating fat requires calories that HAVE to come from food. Eat few enough calories and you WILL lose weight. Eat zero and you WILL die. Eat 20,000/day for a year and you WILL get very fat.

A good example of this is this man went 382 days without eating

https://www.diabetes.co.uk/blog/2018/02/story-angus-barbieri...

He had a calories surplus for long enough to weigh 207kg. While not eating his body consumed energy in his fat to stay alive and he got down to 81kg. ((207-87)kg * 7700 calories/kg)/382 days = 2539 calories/day, which is a very plausible number.

[hgomersall]

The problem, which I can't work out if you know about but ignoring or are ignorant of, is that humans have inordinately strong control systems to maintain some state, as well as hugely influential effects from e.g. a gut biome.

To say "it's just thermodynamics" might be right as far as the physics goes, but it doesn't recognise that biological drives overwhelm everything. It's hugely complicated how energy expenditure and steady state energy consumption interacts with weight gain, not least because the body will invariably work to make your actions as efficient as possible to maintain weight. For example, observational studies of hunter societies that might travel large distances daily, energy requirements bear little relation to daily activity after any transition time has elapsed when compared to relatively inactive Western counterparts. These people can't just will their activities to be less efficient if they hypothetically wanted to consume more energy.

Ultimately, the biology will decide what the effect of any intervention is, regardless of how motivated or not you are. Any advice that doesn't explicitly factor that in is just hot air.

[HyperSane]

"humans have inordinately strong control systems to maintain some state"

If energy intake matches energy needs then body fat percentage stays the same.

If energy intake exceeds energy needs then body fat percentage increases as the body stored the excess as fat.

If energy needs exceed energy intake then body fat percentage decreases as fat is used as fuel.

https://en.wikipedia.org/wiki/Basal_metabolic_rate

[argella]

"The human body requires a constant amount of energy for basic operation and activity. "

no, it doesn't. the amount it uses for basic operation and activity will change. shrinking in response to your attempts to lose weight.

[HyperSane]

This is absolutely false. The human body must always consume a minimum amount of energy for basic maintenance. See https://en.wikipedia.org/wiki/Basal_metabolic_rate. While it does vary it also has a hard lower limit.

The basic metabolic rate varies between individuals. One study of 150 adults representative of the population in Scotland reported basal metabolic rates from as low as 1,027 kilocalories (4,300 kJ) per day to as high as 2,499 kilocalories (10,460 kJ); with a mean BMR of 1,500 kilocalories (6,300 kJ) per day.

[argella]

you said "constant" not minimum. don't move the goal post.

https://www.ncbi.nlm.nih.gov/books/NBK572145/

[HyperSane]

When I typed that I was thinking of the basal metabolic rate, which is relatively constant for a person. Think of it as the calories a coma patient would need to stay alive.