Smell is like when you don't wash yourself for a week, quite unpleasant. It's gone on day 3, but on day 2 I am rather staying alone. Then from day 3 you might suffer from bad breath due to ketosis, regular oral hygiene is important when around other people.

I wanted to know myself better, how much I can do and if fasting affects my athletic performance. I did my 3x full-effort HIIT in a row each day and even went climbing steep mountains on a bike on days 2-3 during my first 3 day electrolytes-only fast. The second climb I had to abort in the middle of the climb due to "losing vision", i.e. I perceived my vision was deteriorating in an all-out effort (like when you overdo it with HIIT).

I read some study mentioning that HIIT during fasting helps to keep muscles from breaking down as muscles start being utilized at around day 4 to synthesize glycogen from proteins once liver storage is depleted, so I keep doing it, though days 4-7 only one series a day.