No, I'm afraid that I never wrote anything of the kind. You must be misremembering - maybe someone else's post?
I was given diet sheets for calorie counts under 1000 calories a day by one GP back in the 1970s - I kept fainting away at work whenever I tried to do anything strenuous.
The contestants on that American show - the Biggest Loser were monitored after their stint and they mostly showed reduced metabolic rates - and they said that was one reason for diets failing.
Kevin Hall who led that Biggest Loser study has this new reflection on the meaning of the results:
It's really interesing!
The reduction in resting metabolic rate (RMR), beyond what would be expected from simply losing weight, seems to be linked to the amount of exercise. Generally, participants who managed to sustain weight loss also did a lot of continuous exercise, and also showed the biggest reduction in RMR beyond expected levels.
This reduction actually now seems to be due to the exercise - building on Herman Pontzer's energy adapation work.
In other words, losing weight via dieting doesn't "unduly slow down the metabolism" as a lot of the commentary at the time suggested. It's actually exercise which slows it down, which might seem counter-intuitive.
(It's also not fully explained but certainly exercise generally leads to a reduction in chronic inflammation, and that must be a part of it.)
The big reason for weight regain after dieting isn't this reduction in RMR: generally participants with the biggest long-term reductions in RMR sustained the most weight loss. What does cause weight regain is the appetitie feed-back loop: generally your bod+brain want you to put the weight back on, and long term you may continue to feel as hungry as you did while you were losing the weight in the first place.
This is a grim scenario, but it's where exercise comes in to the picture: the extra calories burned from exercise can balance the excess calories eaten due to the persistent appetite effect. Without the exercise, weight stacks back on, not because of some fundamental slowing-down of the metabolism, but just for the boring old reason, more calories in than calories burned.
For me: I've sustained weight loss for 3 years now, and I think walking for ~2 hours a day has probably played a big part in that. (Hall's study showed participants sustaining weight loss long-term generally did ~90 min moderate exercise a day.)
Also: carbs have no special role in any of this; it's all just calories.
And everybody continued to eat as much as before (below), mregardless of activity levels and weight loss. The most active people had lower RMR and the same calorie intake, but the increase in activity balanced this out. The less active people had higher RMR and the same calorie intake, but not enough activity to balance things => weight regain.
