There are a range of people on the forums, from newcomers to those successfully maintaining substantial changes to their health and weight. – Often the same topics / questions are raised by newcomers and so some members of the forum felt it would be helpful to have one place that they could point people to where these topics are covered.

This thread has been created specifically for that reason.

HOW MANY WEEKS to do Fast800? People often ask if they can do Fast800 longer than 8 weeks, and does this slow down our metabolism.
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🟡JGwen wrote: None of us on here are posting as medical professionals with the ability to advise on following the BSD. What I like about this forum as well as its friendly, supportive atmosphere is that there are people who have been interested enough in the process to go on to locate articles, podcasts and even books on the science behind the BSD, including more recent research on the topic and we share links to the on a thread called Take a Look At This. – If you search through the list of threads on the forum you will find it,
I have seen it written elsewhere about limiting each round of BSD to 8 weeks. The book itself recommends avoiding a high carb diet, but it doesn’t record the level of carbs in the menus, or give advice on the ideal ratios of carbs, to fat and protein and doesn’t mention ketosis v calorie counting.
Our bodies do not have a mechanism to register, or control processing of calories. They see food intake as either carbs, protein or fat. If we take in too many carbs at any point in time which would increase blood sugar levels our body releases insulin to shunt the sugar out of our blood streams and into short term storage. While Insulin levels are high our body switches off its ability to burn fat for fuel, and focuses on burning off the stored sugars. When insulin levels are low then our bodies can use fat for fuel and because that involves turning the fat into ketones its known as ketosis.
If you spend a period of time where you do not keep your carb (and protein) levels low enough to be in ketosis and restrict calories then once your body has used up the sugar stores it considers you are in a starvation situation because it can not access your fat stores for fuel. Our bodies being clever respond to starvation by becoming more efficient, which means reducing your metabolic rate.
So we have three options.
1.Short periods of lowish carbs and counting calories. No one is certain how limited the periods of this should be but the general feeling is 8 weeks is the max you should do this.
2. Restricting carbs sufficiently so that you are sure you are in ketosis. Generally considered to be at less than 20g of carbs per day.
3. Test yourself to find out the level of carbs you can consume per day and still be in ketosis. Some people can be in ketosis on 50g of carbs and competitive endurance sportsmen can achieve ketosis on 100g a day. (If you want to do this the cheapest and most effective method is one of the cheap breathalysers AT6000)
With options 2 or 3 because you are in ketosis and your body can access your fat stores it has plenty of fuel so the reduction in metabolic rate is considered to be negligible.
Hope that helps.
🟡SunnyB wrote:
Firstly, let’s be clear that none of us here speak as medical professionals. However, many of us here have done the 800 for 8wks more than once and some have done so back to back. Some have also gone on to successfully maintain long term on slightly increased carbs, which would suggest that their metabolism has not suffered.
My understanding is that the Facebook group is very dogmatic and judgemental and several people have joined us here, having had a bad experience if that group. Here we endeavour to be supportive and encouraging; to share our knowledge gained through experience and to celebrate successes whether on the scales or off.
Feel free to join in on any thread that appeals to you. The weekly and monthly threads are good ones to join, as the posters are both newbies and oldhands, so there is plenty of knowledge to draw on.
🟡caronl wrote:
SunnyB and JGwen have given you very good advice. I think as far as Michael Mosley is concerned, the guidance now is that you can stick at 800 cals for up to 12 weeks (I think the limit that the Newcastle diet has now tested). Thereafter, MM advises different approaches for maintenance/further reduction, depending on whether you are at a healthy BMI or not. Why not just get started and tackle this issue further down the line? You will be very welcome – in particular the weekly and monthly threads are normally very active and full of good advice.