The diet works if you give it a genuine try. I lost 18kg over a one year period. Pick your two fast days so that they are convenient to you. I do my two days consecutively on Monday and Tuesday and that suits me. Pick something that suits you. My fasts are zero calories as I cant be bothered counting calories. But once again choose something that is do-able for you. Most people do 500-600 cal per day on their fast days. Before I started my 5:2 diet I got rid of anything in my cupboard that had lots of sugar in it. No more ice cream, chocolates, sugar based soft drinks, chips/crisps, biscuits, “healthy muesli” which can contain up to 35% sugar!! etc. Once I did that I just jumped in and did it. Its not as hard as it seems. Drink lots of water or lemon squeezed water (no sugar!!). I chew gum like its going out of fashion while on my fast days, it helps. Try and go for short gentle walks while fasting, it takes your mind off needing to eat food. You may get headaches during your fast days, but this disappears after a few weeks as your liver starts working better at converting fats into glucose/ketones.

Good luck with it.