I'd wager you've never been overweight.

Eliezer has mentioned many of the things he has tried to lose weight (including ketogenic diets and even clenbuterol). I've tried all those he has mentioned. The difference is for me they work (I call it 'cutting' and can merrily play around with my body composition all sorts of ways). But if, like Eliezer, I had expended huge amounts of effort and my body did not respond significantly then I would update my expectations.

Things that are expected to fail have low expected value. Sometimes you need to shut up and multiply instead of shut up and do the impossible.

What's the likelier explanation for a lack of action, expected value calculations or - here it comes - 'akrasia'.

Expected value calculations. Unless you are making accusations of lies---outright fabrication of self reports.

Depends from whose point of view. E.g. passing away in the knowledge that you've contributed to the eventual creation of FAI (which gives you fuzzies, or at least utilons) can be outweighed by living decades with more mental energy (which also contributes to your development efforts) and a better self-image.

For the purpose of declaring an accusation of irrationality false the relevant point of view is Eliezer's. If Eliezer had someone else's values then it would make sense to evaluate the rationality of a given choice for him according to those other values.

For metabolically priviledged people, or just those with an easy to fix problem such as hypothyreodism, the statement is probably true.

Yes (or at least it would be up there on the list). It just isn't true in this case.