Have been doing fast 800 for about 6 weeks and have lost 10kg. From 101.5 down to 91.5kg, only 6.5kg to go. Very happy so far. I am currently doing 3 days of High intensity training a week on a stationary bike, that consists of
4 min warm up,
12 x 15 second sprints, followed by 45 second rest,
4 min warm down

I am mostly managing to stick with 800-1200 calories a day (with a low carb intake). My concern is that on good days (800) that involve an exercise session i am starting to be concerned that instead of burning fat i am burning muscle.

Questions is
1) How do i know if i am burning FAT or MUSCLE?

I really do not want to be burning muscle. An alternative question might be how best to stay in the fat burning zone ! Any comments tips appreciated but surely there must be a scientific answer to this. Measure the blood sugar level? Amount of Ketones in expelled breath?

Cheers Wobbly

I just googled your question and came up with a few things including the Livestrong.com website (artical 447634). Basically, to paraphrase, from that site if, as you are? Doing more cardiovascular exercise, less strength training (although it is a good idea to incorporate strength training into exercise regimes) and eating adequate protein (think this is 1 – 1.5 grams/kilo of ideal body weight and low carbs you should be losing fat not muscle. Also, apparently, burning fat means your energy and mood levels are more stable throughout the day – they fluctuate more when fuelled by carbs.

Thank you very much for your response. That is really interesting, I have just started, last few days, trying to add in some strength exercises, and it that is what prompted me to register and make this post. Will read the article with interest.