Personally, I mainly eat mixed meals. I think that though I calculate according to the carbs, the dose is really based on eating relatively similar proportions of protein/fat/carb . Larger or very fatty meals are better dosed with a dual bolus which means a bit of the insulin is given upfront and the rest is given over a period (this is a pump option)
If I eat a meal with very few carbs (eg:English breakfast or an omelette) I certainly need to dose for it and tend to use 'educated' guesswork ie what seems to be right based on previous experience
Here's a non simple answer using the info from a Dr who tends to be in favour of lower carb diets, .Dr Katharine Morrison
She suggests both a carb bolus and a protein bolus but using different insulins for the two components. Rapid for the carbohydrate and regular, which takes longer to work for the protein element.
She uses the weight (in ounces) of the protein food to calculate the insulin and suggests a formula of 2 units of
regular insulin to cover 3 oz of a high protein food.
http://www.diabetes.co.uk/forum/threads/advise-please.7034/#post-61596
Here are some examples :
for a person who uses I unit of rapid per 7g carb.
3 boiled eggs and a low carb muffin (10g carb)
for the carbohydrate element 10/7= 1.4units of rapid insulin (or 1.5 with a half unit pen)
for the eggs, this is 3oz so she suggests 2units of regular insulin .
chicken breast salad and berries/cream.
10 g carb .The chicken is a 6oz portion.
Once again the person takes 1.4units rapid for the carbs
Chicken: 6oz (6/3= 2, 2x2=4) 4 units of regular for the protein
The Diabetes Diet: How To Manage Your Diet For Weight Loss And Incredible Blood Sugar Control [Kindle Edition] Katharine Morrison, Emma Baird
Back to me: if I had a chicken salad for lunch my chicken portion would be a little smaller (more like 4-5oz) but I'd probably eat another 20-30g carb from potato or bread. .My insulin dose would end up about the same.
.