Sources and references for: Weight Gain during Holiday

Question:

I Go Up in Weight Every Time I Go on Holiday

I just got home from one week's skiing holiday and I find I have gone up 4 kilos in weight despite a large amount of exercise every day. It will take me months to remove this unwanted weight, and this happens nearly every time I go on holiday. Must it be like this? Is there anything I can do about it? How can I avoid weight gain during holiday?

Sources, references:

1. The personal experience of Gunborg Palme, certified psychologist and certified psychotherapist, teacher and tutor in psychotherapy.