The FastDay Forum

The 0.8 g/kg is a generic guideline for typical eating. I recall hearing <30g protein per day on fast days somewhere, probably the paper by Varady http://ajcn.nutrition.org/content/90/5/ ... nsion.html where the carbs are 60g, protein just under 30g, fat about 12g and fibre 10g.

[carorees]

Also I spotted an interesting research paper the other day (http://www.ncbi.nlm.nih.gov/pubmed/22527168) which looked at the relationship between protein intake and IGF-1 levels. They were interested in how diet could affect prostate cancer risk (high IGF-1 increases risk). They found that increased dairy protein in particular increases IGF-1.

[carorees]

Finally found some info about cheese! This is from Brad Pilon's blog http://www.bradpilon.com

Milk and other dairy products raise IGF-1 levels more than dietary protein found in meat. Milk contains carbohydrates, and drinking milk raises both glucose and insulin levels. What makes milk special is that the increase in insulin is actually three to six times what would be expected or predicted from the carbohydrate load in the milk serving[i]. This is true for skimmed and full-fat milk, but not for cheese[ii]. A glass of milk added to a low glycemic index meal can boost the insulin response 300%, to the level produced by a high glycemic index meal[iii]

Refs:
[i] Ostman EM, Liljeberg Elmståhl HG, Björck IM. Inconsistency between glycemic and insulinemic responses to regular and fermented milk products. Am J Clin Nutr. 2001 Jul;74(1):96-100.
[ii] Holt SH, Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997 Nov;66(5):1264-76.
[iii] Darwiche G, Ostman EM, Liljeberg HG, Kallinen N, Björgell O, Björck IM, Almér LO. Measurements of the gastric emptying rate by use of ultrasonography: studies in humans using bread with added sodium propionate. Am J Clin Nutr. 2001 Aug;74(2):254-8.

So it looks like, as we guessed, cheese is not so bad! Hurrah!

I haven't found a study yet which shows benefits from intermittent calorie reduction where the intake of protein exceeded 30g per day *on the fast day*. References welcome

[carorees]

This recently published paper looks at the effect of a high (ish) and low protein diet on weight loss and of maintenance of fat free mass.

A [protein intake] of 0.8 g /kg/day is sufficient for body weight management, whereas a [protein intake] of 1.2 g/kg/day is necessary for preservation of REE and a stronger initial sparing effect of FFM and lowering of DBP.

I wonder how we might translate that to 5:2 practice? 1.2 g/kg on fast days and 0.8 g/kg on non-fast days? Or 1.2 g/kg throughout the weight loss period and lowering to 0.8 g/kg when in maintenance in order to gain the mooted IGF-1 benefits?

http://evidencebasedfitness.blogspot.ca ... h-you.html has an opinion.

Not got to the full study yet, but the above points to the usual tiny difference in REE measurements and also notes that after the second weight loss phase (33% calorie restriction) the statistical significance of FFM had gone away.

Is there any counter-evidence? If we go lower and risk loss of FFM (bad, presumably) do we also encourage autophagy (good, presumably)?

http://www.ncbi.nlm.nih.gov/pmc/article ... /table/T2/ lost less than 1 kg of FFM on average, with 20% protein on modified ADF with 20-30% of TDEE on fast days. This study had reductions in both systolic and diastolic BP. (Not sure I've seen this one before). Impedance analysis of body composition.

http://ajcn.nutrition.org/content/81/1/69.long is true ADF (zero calories hence zero protein alternate days) and showed a loss of FFM by DEXA of 0.6 kg.

"FFM decreased slightly in all diet groups, without differences between diets" according to the group which published the paper in the OP, in a separate paper at http://www.ncbi.nlm.nih.gov/pubmed/22935440. Isotope dilution used for body composition - FFM was calculated by dividing total body water by the hydrating factor 0.73.

A short period of true ADF with no significant weight loss or body composition change reported at http://jap.physiology.org/content/99/6/ ... nsion.html using DEXA showed a ~1 kg reduction in mean FFM

Varady's modified ADF uses <30g protein per day on "fast" days http://ajcn.nutrition.org/content/90/5/ ... nsion.html which resulted in " Fat mass decreased (P < 0.01) by 5.4 ± 0.8 kg after 8 wk of diet, whereas changes in fat-free mass were not significant (−0.1 ± 0.1 kg) " using impedance measurement.

Similarly Varady reports "fat mass decreased by (P<0.0001) 5.4±1.5 kg and 4.2±0.6 kg, while fat-free mass remained unchanged (ADF–HF: 1.1±1.3 kg; ADF–LF: 0.5±0.7 kg)." in modified ADF 25/125 % of TDEE at two fat levels. DEXA analysis. http://www.ncbi.nlm.nih.gov/pubmed/23612508

While I agree that high protein (up to 35% of dietary intake) is beneficial to fat loss in prolonged calorie reduction my opinion is that the ADF trials do not provide an evidence base for its use and I fall back to the Horizon documentary and "go go mode" and all that where eating less protein was a key part of the argument for better health outcomes.

Of the published trials of IF only Harvie's 2-day low carb diet uses more protein, around 50g per day on restricted days.