I'm roughly the same height and weight as the woman (approx. 5 foot 7 and 60kgs, dress size 8).
I eat "crap" every day - for example at work I'll often buy a pack of jaffa cakes when I go out to grab my lunch and scoff the lot.
I used to think I ate loads, but recently I went for a weekend away to a hotel with a couple of friends who are both bigger than me (both around size 14ish) and noticed that they both managed to finish the three course dinner easily whereas I was struggling to finish it, and one of them had extra chips on the side too. So maybe I don't actually eat as much as I think I do.
I very rarely drink alcohol, and when I do it is just one drink (except for on very rare occasions).
I also exercise each day (or at least I did when I was not pregnant and suffering from severe sickness). On an average day I would cycle 15 miles to and from the station as part of my commute.
Even on days when I drive to the station I would still walk 20 minutes from the station in London to my workplace, then I would probably walk another 20 minutes at lunch time to get lunch/run errands, then another 20 minutes back to the station at the end of the day. Plus sometimes walking to meetings etc. So 60 or more minutes walking per day without even thinking about it.
Plus at weekends I would do longer bike rides, run etc.
I am also a fidget like the woman in the programme, so when I am at work I am constantly getting up to walk to the kitchen, loo etc