Hi Dominic,
JGwen, who is very intelligent and very well researched, gave some great information about this just recently. I am copying and pasting her information below (JGwen, I hope that is okay?).
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The BSD book does not give any guidance on carb levels, and it also makes it clear that this is an eating plan for an 8 or at a stretch 12 week program. – It recommends that we should not follow this way of eating for longer. So those of us with a lot of weight to discard have to make our own decisions on where to go after that 8 or 12 week program.
Many of us who have been on the forum for a long time have been inspired to read the research and work out a program that fits with their specific personal situations. However, there is one fundamental fact. that we need to incorporate into our plans. Insulin is like a switch, when insulin levels are high our bodies can not access our fat stores and is trying to push excess sugar out of our blood streams into storage. When insulin levels are low then our body can access our fat stores for fuel. If we keep calories low and at the same time insulin levels are high our body is put into a situation where it has to adapt and reduce our metabolic rate. – That’s not good. So we don’t want to try to combine 800 calories and high insulin for any period of time. – Read the research into the impact on the metabolic rate of the Greatest loser program, I think they followed all the contestants on the 16th series.
Which raises the question if we have a lot of weight to discard, what level of carbs can we tolerate and still have insulin levels low.
– There is no one answer that fits all. – Elite sporting cyclists can be in ketosis on an eating program which includes 100g of carbs a day, while those who are very insulin resistant have to be under 20g of carbs a day and a single day above that means it will take 3 or 4 days of being below 20g of carbs to return to ketosis.
Personally I have used one of the cheap breathalysers to work out where I am on the scale of carb tolerance After following this way of eating for a couple of years and at the point of having discarded over 40kg, I was still at the point that 26g of carbs a day was my limit, any more than that and I was out of ketosis and even with time restricted eating and being under 20g of carbs it took me upto 3 days to return to ketosis depending on the level of physical activity.
Can that be improved, can you in time support your body in healing and tolerate a higher level of carbs. I believe so, I believe that by staying in ketosis for extended periods of time, and by increasing periods of fasting you can help your body to heal. By improving the mixture of gut bacteria (reducing the percentage of carb digesting bacteria through not feeding them) and helping the body to improve on insulin sensitivity. one cell at a time as the body renews cells.
So in summary, I think, that the best for anyone to do is to measure their response to carbs and make a plan for themselves.
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I hope that helps answer your question. In short, you need to keep carb levels low to ensure you don’t harm your metabolism.
Donna.