Staying in!

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I've realised that it's been relatively easy to stick to my 1300 cals/day since I started on January 2nd because I've not been out anywhere social or had any drinks. I've got lots of things coming up now, parties, meals out, weekends away etc. One alcoholic drink and I'll be over my daily cals, and this doesn't take account of eating all the foods which will be much higher in cals than what i have been eating at home. I am worried that a few sociable occasions and the pounds I've worked so hard to lose will go straight back on. Apart from nibbling at these occasions, does anyone have any advice?