The FastDay Forum

the ADF studies with true fasting have 36h without food.

Fat Free Mass (includes water) fell, but significance was less than that of fat mass. 3 weeks only :-

still think we haven't really got to an answer. this study, like Dr Varady's, measures FFM not muscle mass so doesn't help. I will try to look into this more when I am back in front of a PC instead of a smartphone!

so we're looking for protein balance during fasting ? urine nitrogen balances and that sort of thing....

Should be a fair bit about that, the PSMF (protein sparing modified fast) treatmeents arose from heart failures due to (heart) muscle loss on very low calorie diets so I would think there's plenty of stuff from the 80s or possibly earlier.

http://www.ncbi.nlm.nih.gov/pubmed/15380889 compared surgery patients who were given either the usual 18h fast before surgery followed by glucose only at 7 kcal/kg/day (560 cals for 80kg subject), or a novel approach of parenteral feeding (tube etc) of double the above calorie rate of glucose plus the same calories of fats plus 1.5 g/kg/day of amino acids (protein).

In other words the comparison in post-operative feeding regime is between 560 cals of glucose and 2720 calories of balanced 41:41:18 C:F:P feeding both before and after surgery.

The standard group (fast then glucose only) lost 1 g protein/kg/day whereas the nitrogen balance for the fed group showed no significant change. Protein synthesis rates were unchanged.

Detailed analysis showed that the protein loss was not from muscle "This fact suggest that muscle protein breakdown begins after the first 24 h post-surgery, and that the protein donor during the early response to surgery should be an organ other than skeletal muscle. In agreement with our findings, it has been demonstrated in dogs that skeletal muscle protein breakdown does not begin immediately after injury and the degraded protein in the first 24 h after surgery is mainly of intestinal origin."

Although this study is based around a surgical intervention which normally triggers protein loss it does give some leads in the "how not to lose muscle" debate. Now to follow the references.....

[carorees]

Intestinal origin? Could that contribute to the digestive disturbance some people get?

[carorees]

Did you see this from Dr M on the fast diet website?
http://thefastdiet.co.uk/does-intermitt ... eficiency/

He's slacking of late, the Varady studies use 15% of calories as protein and MM talks of advocating higher protein. Hmm.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2673798/ looked at the matter of elevated IGF-1 in long term calorie reducers (humans) that conflicted with the results in rats. They thought the high protein diet of the CR people may be responsible, as a matched group of low protein vegans had lower IGF-1.

As a first step in evaluating this possibility we were able to arrange for six of the CR volunteers to reduce their protein intake from 1.67 ± 0.1 g kg−1 of body weight per day to a protein intake of 0.95 ± 0.1 g kg−1 of body weight per day for 3 weeks. This short-term isocaloric reduction of protein intake resulted in a 25% reduction in serum IGF-1 concentration (from 194 ± 34 ng mL−1 to 152 ± 41 ng mL−1; p = 0.01) in the six CR individuals, suggesting that the high protein intake was preventing a reduction in IGF-1 levels in response to CR.

Caroline, this post of Dr M's is where this topic started. He doesn't dispute Dr Lau's contention that muscle loss starts within the first 24 hours of a fast. Dr Varady's research doesn't measure muscle mass loss only FFM so doesn't challenge Dr Lau's assertion I think.

I wonder what Dr Longo or Dr Matson would say about the protein issue. Both have favoured a longer fasting period.

[carorees]

Caroline, this post of Dr M's is where this topic started.

Ha ha, do I win a prize for bringing us back to the start?

I have been drinking a protein shake every morning for years. It contains 24 gm of protein. I was thinking of having half a shake on my fast days but now I'm not sure if I should have it at all. I usually have chicken for dinner so maybe I'm getting too much protein.

I have been drinking a protein shake every morning for years. It contains 24 gm of protein. I was thinking of having half a shake on my fast days but now I'm not sure if I should have it at all. I usually have chicken for dinner so maybe I'm getting too much protein.

How does your protein work out in grams/day/kg body wieght ?

Luigi Fontana concluded...

In conclusion, our findings demonstrate that, unlike in rodents, long-term severe CR does not reduce total and free IGF-1 levels in healthy humans if protein intake is high. In addition, our data suggest that chronic protein intake is more powerful than calorie intake in modulating circulating IGF-1 concentration in humans. This is important because the median protein requirement of the healthy adult population is 0.65 g kg−1 per day and the reference daily intake (97.5th percentile) is 0.83 g kg−1 of body weight per day (Rand et al., 2003) that is close to the protein intake of our vegan group in this study. In contrast, half of the US males are eating 40% or more protein (≥ 1.34 g kg−1 per day) than the reference daily intake (Moshfegh et al., 2005), which is presently considered to be harmless and, according to public opinion and advocators of ‘low-carb’ diets, may even be beneficial. More studies are necessary to understand the biological and clinical implications of a chronic high protein intake, especially in sedentary people with a positive family history for cancer.

Caroline, this post of Dr M's is where this topic started. He doesn't dispute Dr Lau's contention that muscle loss starts within the first 24 hours of a fast.

There's a continuous breakdown and synthesis of muscle proteins, with elevated insulin inhibiting breakdown. So anything that drops insulin, including a fast, will tend to increase breakdown. Of course with adequate post-fast protein availability the increased synthesis and reduced breakdown from elevated insulin could quickly repair the lost muscle.

http://www.medscape.com/viewarticle/557636_5 says "Measurements of protein synthesis and breakdown after a 12-hr fast indicate that breakdown exceeds synthesis, so net protein balance is negative" which confirms what Lau says.

Fig 4 in http://www.ncbi.nlm.nih.gov/pmc/article ... 73/?page=7 shows a nitrogen loss of ~14g/day on day 1, ~11g/day on day 2 and 5g/day after 25 days total fasting (while demonstrating that infusing leucine reduces the loss). 14g/day of N is 87.5g of protein ( * 6.25).

[carorees]

What about the role of GH?

I've been away for a bit so just trying to get back up to speed here. (Lots been happening while I've been gone I see - but not on this topic!) I have still been pondering this protein issue ie is it 'dangerous' to go without protein for a relatively long period (18-24 hours say) on a fast day.

I found this quote posted v helpfully (as always) by PhilT but on another thread which I had not studied as closely as it merited before. It is from the recent Dr Varady trial (pub Jan 2013) [ADF-HF = alternate day fasting with high fat diet on non-fasting days, ADF-LF = alternate day fasting with low fat diet on non-fasting days] :

Body composition was also favorably altered with both diets. To elaborate, fat mass decreased to a similar extent in the ADF-HF group (5.4kg) and the ADF-LF group (4.2kg). As for fat free mass, non-significant increases were noted for both the HF diet (0.6kg) and LF diet (0.5kg). These data suggest that the weight loss observed with ADF results from a decrease in fat mass, and not fat free mass. A similar preservation of lean mass (0.5kg) was noted in a previous ADF study conducted by our group [15]. Interestingly, this retention in lean mass observed with ADF is not replicated with CR diets. For instance, consistent reductions of 3%–5% in fat free mass are generally noted after 8weeks of 25%–40% CR [16], [17]. The reason why ADF may assist with the preservation of lean mass is not known at present, but will undoubtedly be of interest in future studies in this field

It's true that they measured fat free mass (FFM) and not muscle per se but it does seem to me highly implausible that such results could have been obtained if the subjects were actually experiencing significant net loss of muscle, and yet they were undergoing regular 18 hour protein fasts (twice in succession on alternate days).

So as PhilT has suggested above, it seems to me that whatever muscle loss may occur during a fasting 'window' is fixed by a corresponding 'rebuilding' afterwards. So we don't need to worry about it.

Could this be the famed 'autophagy' at work? The shortage of available protein actually forces the body to 'spring clean' old tissue to release essential amino acids, and this process (maybe) has the long-term benefit of reducing the amount of old potentially cancerous tissue?

Hey, you lot seem like you might be able to answer a question! I lost 1.2kgs last week doing ADF. Around half of that was sadly lean mass. What could I be doing wrong? Or in your opinion what could I change? I have the main meal at dinner. I'm vegetarian so my protein is mainly plant based. It tends to be lentils, brown rice and occasionally eggs. Would you have any suggestions?