Two words. Portion & Spacing
Portions: This is quantity and is pretty simple to understand. Meaning if you eat more you will gain more weight. Not counting the acidity
So you must eat less rather than more to keep your weight in control in the festive season.
Spacing: If you eat the portion that you decide for yourself at one go, the body is likely to think that there is abundance and swiftly assign the plenty to your hips. Where it is likely to stay for life. So one must eat a little at a time.
Here is how I go about doing it.
On Diwali day, I eat our home sweets. As stated earlier we all allow ourselves one piece per sweet. So there might be say 3-4 sweets and some savories for that day. In any case it should not exceed one dinner plate in quantity. Not heaped, if you are looking for that loophole here
After my puja I might take one sweet and one savory. Then after some crackers bursting I will have my breakfast which might be idlis.
Around 11 when I am feeling peckish and as I am wiping the sweat off my brow, having distributed all the plates to my neighbors, I will partake of another sweet.
Similarly post lunch, tea and post dinner will find me spacing the plateful of sweets and savories spread through the day.
On the day after Diwali it is the turn of my neighbours sweets which I have decided to retain for myself. Mostly those that are homemade.In similar fashion I have one plateful spread through the day.
Over the 3-5 days that these sweets keep coming and going the principle is the same. One plate per day. Spread through the day.
And knowing fully well that I am partaking of sweets, my main meals will be reduced in quantity.
Most times I have had about 25-30 sweets over the festive period and not gained weight at all. Or a little which can be easily controlled with post Diwali, guilt assuaged speed workouts.