Hi all, I am about to start the diet but I am hesitating a little as I am training for a marathon. My weekly mileage is 30-40 miles a week – is this going to be a problem? Any advice would be appreciated. I have read the book twice and meal planned for the next few weeks ready.

Well I would say it depends on why you want to do the diet. Are you diabetic, or pre diabetic, on medication or doing this for weight loss? More detail would be helpful in giving our thoughts.

Just to say I run, furthest distance so far just over HM distance but did it while on the diet and continue to do so while following the principles.

Many thanks for the reply. I am doing it for weight loss. I have a BMI of 25. I need to lose 1.5 stone. I am not diabetic, pre diabetic or on any medication. After my marathon I will continue to run about 20 miles a week but I just wasn’t sure if the extra miles would mean this diet may not suit.

To be honest I wouldn’t do the 800 cals but I would eat to BSD principles. By eating lower carbs (and very few or 0 simple carbs) your body will learn to switch from carb burning to fat burning and during runs make that switch more quickly. And as long as you eat good, wholesome food and don’t give into the munchies or treat yourself with food you should have weight loss and/or shape changing as a result. The general population has plenty of fat to burn and this lasts longer than the generally accepted 90mins or so of stored carb. When I first started to get fat adapted, rightly or just in my head, I felt I could feel the change happen as I suddenly felt spent during a run which cleared after a minute or two (may have been quicker just felt a while). I have started marathon training now for one later in the year, although I haven’t committed to the event yet, am eating mainly BSD and won’t be carb loading. At my last HM event I spoke to a lady who has coeliac disease and she told me she had run London without breakfast. Just to say I am not fast or in it to win it. I just run and do the occasional event because it’s my thing. Good Luck with your training and event. Also Google running fat adapted.

Hi neveragain I think you have answered your own question. If you want to do a marathon and need to train extensively and then continue to do lots of intense exercise (20 miles a week) then this diet is probably not for you. This diet is designed to shock the body into removing visceral fat and kick start the pancreas into producing its own insulin or re-training the body on how to successfully use the insulin already there. It is not really a weight loss plan in its original form. If you want to do it for quick weight loss then it might be an idea to increase the calories by a small amount to coincide with the exercise. For example, I swim daily and know I can swim an hour after breakfast or lunch, I know I cant swim a short time before food as I will have a hypo. If I have to mistime it I will have a small snack of around 50 calories like some yoghurt and a couple of prunes but that will be deducted from my 800 calories, not added on. In short, if you really want to do the 800Fast BSD you have to stick with 800 calories and no bad carbs.

Feeling a bit guilty about being a bit harsh and prescriptive I would add to my advice that if you are going to do this diet in whatever format you choose then you are to be congratulated in taking positive steps to improve your situation.

Thank you very much for the replies both of you. I think I may do a slight adjustment and still stick to the principles but not do the initial 8 week plan. On my running days I will have the porridge with apple instead of eggs. Thanks again, feeling more confident to start – just needed clarification. Thanks again

Just to say make sure you use “proper” oats and not the instant sort. On the odd occasion I have porridge before a very long run I keep the quantity to a max of 30g, more usually 25g, and add a teaspoon of crunchy whole earth pea nut butter stirred in – lovely. Personally I’d give the apple a miss before a run as I know it would give me indigestion. The other thing that’s important to running, as I’m sure you know, and a cornerstone of this way of eating is to make sure you stay well hydrated at all times. I would love to hear how you get on. Best wishes

Thank you – I use the plain porridge oats from the supermarket – is instant the ready brek type product? Yes I need to hydrate more I am terrible for this.