I think its just where you add all your syns together for the week - 7x15=105 and then use them as and when you want instead of sticking to 15 per day.
SW don't generally recommend this but it seems to work for loads of people and its good when you have a special occasion to go to when you know its gonna be difficult to stick to plan.
My WI is on friday morning so I tend to have a drink or two (or more) on saturdays, when I get up sunday I see how many syns I have left from my allowance and then share them out with the rest of the days.
Flexing synning is allowing yourself to exceed your syns for a one off special occasion. You set a limit in advance so that you are still in control. Afterwards, you go back to food optimising and 5-15 syns per day. The theory is it allows you to have a normal life and enjoy special occasions without completely letting go. If you just went out and blew your syns, you might get into a situation of thinking "ive blown it anyway, what's the point?", and be in danger of going off plan even more. The limit means you retain some control, meaning you still have a sense of achievement. SW suggest that you may not lose if you flexi syn, but equally you might not gain.
The other method people use and what the previous poster has described (though not advocated by SW) is to save up a portion of their max 105 syns for the week for a night out, weekend etc - seems to work for lots of people whether SW like it or not!
thats how i understood it mandy296 . . . . but i didnt think it would work . . . im goin to my dads for easter and there will b lots of drink (mayb not so much food lol) forced upon me and was wonderin if i could flexi syn but its gonna b megga syns so was thinkin i'll b gud all week ave a bit of a blow out over the weekend then get back on track next week n hope ive not done tooooo much damage x
Our consultant in Larnaca (Cyprus) told us recently that she'd been back to the UK for training and they told her now that as long as you stay within your 15 syns a day for six days of the week the other day you can go up to 30-40 syns without it affecting your weight loss. That's what she said. Of course that may not work for everyone I guess. I think for me it's best to try to keep to 15 syns a day but if I should not be able to it's conforting to know that Slimming World are saying that you can have a pig out once a week!! Mind you, I have not been to group for two weeks - maybe the other members are saying that doesn't work!
I lost nearly 2 stone before Christmas with SW, and right from the get go I would give myself a flexi-syn day of up to 50 syns the day I got weighed (9.30am weigh in) after eating and drinking nothing before weigh in I would then flexi the rest of the day, then stick to my 15 for the rest of the week. I lost every week but, at 23 stone when I started, there is a LOT to lose, that might make a difference.
I went off track over Christmas, and have just started back again, lost only half lb yesterday, but hadn't really stuck to the plan for the week.. getting back into motivation now, hoping this site will help!