The FastDay Forum

[carorees]

Here is an interesting study that looks at the balance between fat and carbohyrate burning (oxidation) in men who fasted overnight compared with 72 hour fast. After the longer fast, more fat was burned even after eating a meal.
http://www.ncbi.nlm.nih.gov/pubmed/11133906


This is interesting as it suggests that there may be some kind of lag between the availability or otherwise of different fuels and what the body uses.

Many if not most people when starting 5:2 find the first few fasts difficult, which I have thought is probably due to the body being 'reluctant' to start fat burning. This study suggests that after a prolonged period of fasting when carbohydrate is available again, the body may be 'reluctant' to change away from fat burning.

Of course the men in this study were fasting for a lot longer than we do. Nonetheless, it might be a potential mechanism that might prevent weight going on during feed days, if we can get a good fat burn going on fast days! It may also add a bit of weight to my theory and that of other IF gurus that it is important to avoid carbohydrate when fasting.

Thoughts people?

The glucose and insulin both get a lot more excited after the meal in those that have fasted longest, as if the systems were focussing on fat utilisation and failed to notice the glucose arriving or as you say being reluctant to respond.

The massively higher levels of free fatty acids and ketones in the blood of the longer fasting subjects would also take a while to clear and perhaps impair carbohydrate utilisation - did the glucose just get used to reload the liver with glycogen ?

Caroline, from all the research I've done it appears that it is a good idea to stay clear of most carbs all of the time. A low carb diet in itself will cause the body to burn fat. As you know it's called ketosis and is in my small opinion the best way to burn fat.

The only problem I have with sticking to a paleo or low carb diet is being surrounded by high sugar/processed food, as I find it very hard to resist.

[carorees]

Phil, yes and yes I think are the answers to your questions (FFA impairing glucose and also the glucose being used to replenish glycogen stores).

Shell, I totally agree about giving up carbs being a bridge too far! I lost a load of weight on Atkins but I couldn't keep it up because carbs are so nice and also because low carb, high protein food is so darned expensive!

I go completely carb free on fast days which I think does help. I also try not to have too many carbs on the night before a fast as I think it helps get me into fat burning on the fast day. So yesterday I had eggs for lunch with just half a slice of bread and I had lamb and vegetables for dinner.