Hello, AngelaD – Fifteen pounds in one month is a big shift and now you are trying lots of other new changes to your eating and exercise schedules too. I do wonder whether your body might almost go into shock as a result! Perhaps it needs time to adjust. On the subject of eating too little on non-fast days, here’s a repeat of a reply I made recently to a similar query, which I hope will be helpful: Too little food for too long can put your body on red-alert and it responds by slowing the metabolism down, in order to maintain all the stores of fat it can, to survive during the famine it is experiencing. Hence, weight-loss becomes extremely difficult. Have you calculated your own TDEE (Total Daily Energy Expenditure) yet? That’s the daily calorie intake you need to function properly, based on your statistics and activity levels. There are lots of TDEE calculation tools available online but I advise the following cautions when using them: a) Get comparative figures from, say, three calculators and then pick an average, as they seem to vary a lot; and b) Because, using 5:2, you already manage a sharp calorie reduction two days a week, use your CURRENT weight, rather than a GOAL weight, to do the calculations. Then the resulting TDEE figure will be your appropriate intake for the five non-fasting days and one quarter of that figure (i.e. 25%) will be your personal recommendation for your two fasting days (as 500/600 cals is only a general average). Hopefully, those more accurate figures will give you the kick-start and the positive results you are looking for, with a safe, steady and gradual weight-loss.

Hello, AngelaD – I hope things are going well for you. To answer your question, I started using the 5:2 system at the end of Jan ’13 but had to put the brakes on after 7 weeks, due to a worsening of on-going acid-reflux symptoms, caused by a weak gullet valve. Since then I’ve been practising what I like to call ‘The 5:2 Diet Lite’: I fast for as long as I can overnight, every night, (usually about 12-14 hours, from 8 or 9pm until 9 or 10am) and then I eat sensibly during each day.
After much experimentation, I realised that if I go without eating longer than about 3 hours in the day then I cause myself serious problems with heartburn. Willingly going to bed hungry has been quite a psychological breakthrough for me and my Lite system seems to be working. To date, I have lost 27 pounds (from a start weight of 183 pounds/ 13st 1lb) and my fingers are now crossed that my next weekly weigh-in (on Monday morning) will see me at least hit my special ‘2-stone loss’ marker (by going down one more pound, from last week’s figure of 156lbs/11st 2lb). Then I’m heading for that long-unseen land of ‘Ten-Stone-Something’ (140lbs+) and I will be very happy to reside there.
I think experimentation and patience are key elements when adopting the 5:2 method – everybody’s circumstances, temperament, needs and goals are different and it takes time to find one’s way, trying to balance all those complex factors. I do love hearing other people’s stories but I caution against comparing one’s own progress to any one else’s. Vive la différence! I wish you every success in reaching your goals and in enjoying the process.