Knowledge decreases weight

[Timelord]

More knowledge = less kit.
More knowledge = less chitter.
Those that are regarded as a bit overweight probably have a "normal" metabolism. If you cut out all the modern bad calories, then those peoples weights would probably be about right. For the people who eat the modern crappy diet but still remain thin, then reverting to a natural/subsistence type diet could be a problem! Their higher metabolism could well burn through the calories too fast or if a lower calorific utilization then not enough calories might be taken on board.
(This does not apply to those already on a healthy diet without the modern crap who are not overweight.)
Animals fatten themselves up ready for Winter. It is not a bad thing. Just using it up in the summer months is the seriously hard thing mentally! Creatures of habit and comfort lovers r we humans.. lol.