So how to cut calories and still enjoy Friday night? Firstly, buy smaller challahs and eat them for ha-motzi only - a 2oz portion is 160 calories.

If you miss that slice of something with your starter, try a small tea matzah at 18 calories, and place the liver on lettuce and cucumber. Now the chopped liver: it contains fried onions to add flavour and sometimes the grebens (fatty pieces left over from rendering schmaltz). Omit those. If those same onions are roasted in the oven in their skins, the calorie-count drops from 164 calories per 100g to 34 calories.
After koshering, the virtually cooked livers can be heated in a non-stick pan with a few sprigs of fresh thyme, the peeled or drained onions, half an ounce of Kiddush wine to add extra favour and, when cooked until just tender, processed with a couple of hardboiled free-range eggs. The liver's calories will reduce from 200 calories for a 2oz portion to 148 calories per portion. Or, even better, swap this course for a piece of herring (not chopped herring - 210 calories for 3 oz), heart-healthy at 78 calories for an 1oz piece.
Slim down your chicken soup by preparing it on Thursday. Try to buy a free range bird and begin by skinning the chicken and discarding the skin, then add masses of cleaned and sliced carrots, whole onions, chopped leeks, sticks of celery, a clove of garlic (optional) and salt and pepper. Leave to cool, remove the chicken and scrape off all the fat from the top of the pan. Now your healthy soup is ready to heat. Sadly, kneidlach roll in at 40- 80 calories per ball depending on the size. Better to add a little lockshen - 16 calories cooked per ounce, or drain all the vegetables and process with for a thicker, more satisfying soup.
The remaining cooked chicken can now be roasted off in the oven. (Incidentally, the white meat is much lower calorie than the dark - 175 calories per serving as opposed to 256 calories per serving.) Cover the poached chicken with stock, a couple of low-cal sprays and sit it on a bed of thinly sliced raw potato (one medium per person) and plenty of seasoning, or alternatively use 50g (1 ¾oz) raw rice per person or 150g (5 ½oz) cooked rice per person.
Try brown rice; its natural fibre will keep you feeling full for longer. Vary the flavour by soaking some dried porcini mushrooms in a little water and add a few sliced, fresh mushrooms and mix them in with the rice. Your potatoes or rice will absorb all the rich flavours.
Serve with plenty of sweet-and-sour red cabbage made by simmering finely sliced cabbage in a little chicken stock with a peeled, diced pear; some more onions; a handful of caraway seeds; a generous portion of carrots cooked till tender in half stock, half a glass of orange juice; and a few cumin seeds for sweetness, fibre and colour.
Finally, lockshen pudding, wonderful though it is, is approximately 380 calories for 125g (4oz), while an average slice of strudel is 300 calories.
Substitute it with my luscious low fat strudel. Total calories for your low-cal Friday night, including 25g (1oz) challah for ha-motzi and herring are 883 calories. The diet is back on track.