Does Michael Mosley say anything about weight lifting and cardiovascular exercises in relation to the blood sugar diet? I can’t imagine he still recommends 800 calories if you’re doing fairly strenuous daily exercise.

It is perfectly safe when you are sufficiently fat adapted, provided you are not underweight. The body will provide its own fuel. I played badminton for two hourly sessions every week on 800 calories, around 550 calories burnt each week according to the app, without upping my calories or carbs.

Mixnmatch is right. As long as you have plenty of fat in your body, not something many of us are short of around here 😊 (and are not ripped – I wish!) once once fat adapted you have fuel for lots of exercise. Far more than the 90mins or so stored in muscles as glycogen.

Hmm, what about the advice to increase protein intake when training or engaging in significant exercise?
I recently forgot this advice, and regretted for two days following a particularly active day. ( basically felt like shit and had very little energy for anything)

I’m going to propose that each person has their own exercise/calorie threshold and it is best to try out a couple of different strategies and then evaluate for yourself what works best for you.
Some people like Mixnmatch can exercise and not need extra calories and AnnieW is right, when we are fat adapted we have massive energy stores available to us.
But I found I could not survive on just 800 calories on the days I was doing any hard exercise (burning more than 500 calories a day) and I had to add back in extra calories to keep myself from feeling cruddy or worse, unleashing a ravenous out of control eating binge.
I now add back in about half the calories of what I burn off in hard exercise and that works well for me. I played around with it for weeks to figure out what kept me satiated and still losing (now on maintenance).
BUT, here’s the non-logical surprise kicker: I lost weight fastest, easiest and without hunger issues when I was doing the LEAST exercise and just a gentle, low level exercise like walking and a half-hearted Jazzercise class.
I think hard exercise might trigger a physical response that holds on to fat (and triggers appetite) — very weird — but the difference was absolutely unmistakable. So try it every-which-way and find your own sweet spot! We are all metabolically different.
As a final note: appetite is a mark of health, so I try to honor it — when you are truly hungry (and you KNOW!) you must honor that and feed your body some good food (protein, good fat, veg). Respect your true hunger.

I did increase my protein component, to around 75-77 grams per day or even more on really heavy exercise days, which is significantly higher than many people eat on non calorie restricted diets. My typical exercise ‘fuel’ was, and still is a homemade protein shake ( I tried eating a meal instead but rarely felt able to exercise after eating and my badminton sessions start at my normal evening meal time) with 40g whey protein in it, cocoa powder, 10g carbs in total, and some omega 3 fat and fibre from chia seeds. This was started before my session and finished afterwards, so I had plenty of fuel, even though my daily calories were low. I am a little higher than that now I am on maintenance but have mainly increased fat and carbs (though still mostly healthy ones) to get my calories up.

I am starting to think that when we eat is at least as important as what we eat when it comes to staying healthy, and I am sure that fuelling my exercise like I did was what made it possible for me to continue in the way I did.

I haven’t varied my exercise program much, I was doing the badminton sessions before I discovered BSD, and I vividly remember ‘hitting the wall’ for a few weeks when i went really low carb before the problem just melted away, and I was just as able to keep going as I was on my former carby diet.

My advice would be to keep the protein high for the muscle repair and building, set the fat according to something like Martin Ankerl’s keto calculator to activate the weight loss (Google it, that was my main go to for advice on how to change my macros as my body composition changed) and carbs is whatever is left.

Depending on the type and amount of exercise you are doing, remember during “muscle build and repair” the body will hold on to intramuscular water, so weight will remain higher. Hence why most exercise regimes recommend high levels of hydration before and after training. I noticed that when I worked away from home where exercise was more difficult I lost weight a la whoosh, which I assume was the body simply discharging this water.

Well I just cycled home (uphill, I live in Sheffield) and found it much harder than usual, plenty of walking – I think I need to eat more calories earlier in the day if I’m going to do that!