I've been doing my own measurements, generally once a week, on the morning of the day after Day 2 of my 5/2 diet. Partway along I started keeping track of my breakfasts on that day. The extracted figures below show the increase in blood sugar readings from when I get up to 2ish hours after starting breakfast. The carbo column is my guess at whether the meal contained more than the minimum carbs (I've been toying with LCHF too.). The meals are listed in order of greater blood sugar increase rather than date. I usually take V8 vegetable juice with 2 teaspoons of Physlium Husk, a few carbs, but also extra fibre. The 'seedbread' was mostly flaxseed and seeds.
Increase Carbo
-8.20% No Coffee, skimmed milk, V8. Egg, bacon, cheese omelette, no bread
-4.76% No Coffee, skimmed milk, V8. Kippers
-1.72% No Coffee, skimmed milk, V8. Bacon and cheese omelette, no bread.
3.33% No Coffee, skimmed milk, V8. Bacon and cheese omelette, no bread.
4.48% No Coffee, cream and V8 only
6.90% No Coffee and cream, V8 Seedbread, cream cheese, peanut butter, yoghurt
9.23% No Coffee, skimmed milk, V8. Two sausages, egg, two bacon
11.32% No Coffee, skimmed milk, V8. Egg and Bacon, no bread
11.32% No Coffee and cream, V8. 1 egg plus half tin bacon spam
12.28% No Coffee and cream, V8. 2 bacon, 2 egg, cheese
13.79% No Coffee and cream, V8 Tinned kippers in butter
14.93% Yes Coffee, milk, V8, 3 rashers, egg, seeded pitta
18.64% Yes Coffee, cream, V8, sausage, egg, 2 bacon
21.54% Yes Coffee, cream, V8, 2 wholemeal bread, PB and Marmite
22.22% Yes Coffee and cream, V8. Berries, yoghurt, and nut mix
28.13% Yes Coffee and cream, V8, Salami, Protein Flapjack
28.30% Yes Coffee, skimmed milk, V8. Venison sausage, 2 bacon, egg
29.63% Yes Coffee and cream, V8 Yoghurt, cream, berries, nuts
29.69% Yes Coffee, milk, V8, 2 bacon, 2 vegetarian sausages (breaded potato/cabbage/cheese)
49.12% Yes Coffee, skimmed milk, V8. Bacon and granary bread sandwich
67.24% Yes Coffee, skimmed milk, V8. Bacon and half and half bread sandwich
74.00% Yes Coffee, skimmed milk, V8. Seeded bread, marmite and cheese, peanut butter
109.26% Yes Coffee and cream, V8. 55Gr Mesa flakes and milk.
It seems that I have a sensitivity to bread and refined carbohydrates - but can't say that anyone else is the same. Hope that helps.