The FastDay Forum

http://onlinelibrary.wiley.com/doi/10.1 ... 873.x/full

Reviews studies available at the time (2011) to address the question "Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss?"

[Tracieknits]

Wow, that's very interesting - thank you for sharing! It's very interesting to note that while the daily CR diet makes one lose more weight, they are losing a lot more lean muscle than on the intermittent CR. I have few enough muscles and I don't want to lose them

It's an interesting read. I think people should note that these diet regimes have been studied in people who are overweight or obese so they had weight to lose. Not people of a healthy weight.

I haven't looked at the studies reviewed but it's not unusual for people who are obese to experience a reduction in lean mass. This isn't necessarily a bad thing. People who are obese tend to have a surprisingly high muscle mass as muscle develops in response to transporting their body mass. It follows that this muscle mass will decrease in line with their weight.

However, it's also possible that some lean mass is metabolised during a fast.

Either way, I don't think the reduction in lean mass will be compromising their health whereas the fat mass is.

worth noting that the loss of "Fat free mass" will include muscle etc but also water and the like. Practically all weight loss involves loss of fat free mass usually around 70:30 fat:fat-free.

Measuring weight loss is easy, deciding how much was fat is a lot more complex and also dependent on the methods used.

Here's a much more recent paper by her (and others) http://www.nutritionandmetabolism.com/content/pdf/1743-7075-9-98.pdf.

I confess I don't really understand it though, the paper seems to suggest that the biggest benefit may come from combining intermittent fasting (IF) with calorie-restriction on non-fasting days and 'liquid meals' (IFCR-L) - whatever they may be? Doesn't sound good anyway! Can someone can decode it and tell us whether it casts any light on 5:2 fast diet?

[carorees]

Actually, there are two even more recent papers by the same group:

http://www.ncbi.nlm.nih.gov/pubmed/22889512
and
http://www.ncbi.nlm.nih.gov/pubmed/23171320

As well as the one found by dominic
http://www.ncbi.nlm.nih.gov/pubmed/23113919

It is interesting to compare them all, which I will try to do below.

The first in the list above was published this month and shows that on the ADF regime, it made no difference whether the subjects had a high fat or a "healthy" diet on feed days...they lost a similar amount of weight, fat mass, and waist circumference. LDL cholesterol and triglyceride concentrations were reduced. HDL cholesterol, blood pressure, and heart rate remained unchanged. The study was only for 8 weeks so I don't know that we can read much into the lack of change in the blood pressure etc.

The good news for us though is that we may not have to worry too much about what we eat on the feed days (though of course that is assuming we can extrapolate the results from alternate day fasting to only fasting 2 days a week). (More on this below).

The second 2 papers published at the end of last year looked at using meal replacements vs food in an 8-week intermittent fasting regime where the subjects fasted for one day a week (only 120 cals allowed!) and for the other 6 days had a calorie-restricted (80% of energy needs) diet. One group had liquid meal replacements for breakfast and lunch and a food-based dinner on their 6 days while the other group had a food-based diet for all 3 meals on their 6 days. They aimed to have approximately 240 kcal for breakfast, 240 kcal for lunch, and 400–600 kcal for dinner. The diets were relatively high carbohydrate: (i.e. <35% of kcal as fat; 50-60% of kcal as carbohydrates; <200 mg/d of dietary cholesterol; and 20–30 g/d of fibre). One of the papers reported that weight decreased more with the meal replacements (3.9 kg compared with 2.5 kg)as did fat mass (2.8 kg loss compared with 1.9 kg in the food based diet). Reductions in total and LDL cholesterol levels were greater with the meal replacements, while heart rate, glucose, and insulin, decreased the meal replacement group only. The other paper is, I think, using the same group of subjects as the first but reports on changes in various hormones including leptin, and insulin-like growth factor-1 (IGF-1) which decreased in the meal replacement group only.

In the discussion, the authors say that they think the differences in their findings is due to the fact that the meal-replacement group lost more weight than the food-based diet group.

So, the bottom line here is that once a week fasting when combined with calorie restriction can bring improvements in many factors that are known to increase the risk of cardiovascular disease.

From our point of view, however, it seems that the regimens used in the meal-replacement study bring the worst of both worlds...the every day worrying about calories together with once a week severe fasting. However, they do show that if you fast once a week you will lose weight as long as you cut back for the other 6 days.

It is a shame that neither of the two intermittent fasting regimes studied involved 5:2! However, it is interesting to compare the weight loss achieved over the 8-weeks of the two studies:
In the ADF study, subjects lost about 4.5% of body weight and lost around 7 cm off their waists.
In the 6:1 study the food-based group lost only 2.6% of body weight and around 4 cm off their waists.
Although it is dangerous to extrapolate, we can guess that doing 5:2 with no calorie restriction on the feed days should give us changes somewhere in the middle.

All these regimens resulted in other health improvements though most of them were due to weight loss. Of course the potential benefits in protecting against cancer and Alzheimer's could not possibly be known with only 8 weeks of dieting. The 6:1 regime with the liquid meals did show drops in IGF-1 though so it seems likely that our 5:2 regimen would also do so.

Please note that the interpretations of the findings are largely my own and (apart from the comment about the relationship with weight loss) are not those of the study authors.

Hmm, strange choice of nomenclature.

more recent paper describes a single trial (rather than a review of published work) and compared two groups.

IFCR-L participants had two 240 kcal meals a day of liquid meal replacement shakes etc, and one of food, for 6 days. On the 7th day they had a "fast" of (water consumption + 120 kcal of juice powder only, for 24 h ). The regular evening food meal was "400–600 kcal <35% of kcal as fat; 50-60% of kcal as carbohydrates"

IFCR-F Subjects were instructed to eat approximately 240kcal for breakfast, 240 kcal for lunch, and 400–600 kcalfor dinner using the above food guidelines for 6 days, then on the 7th day to do the same 120 kcal "fast".

Both groups had a 30% calorie reduction overall, compared to their maintenance needs. The statistically significant improvements were seen in the liquid diet group compared to baseline, and in some cases compared to the foods group.

The 240 kcal shakes used are 24g protein, 24g carbs (of which 8g are fiber, US labelling) and 6g of fat. The shake maker's take on the results are here

Thank you Caroline and Phil for your prompt and thorough responses. How very interesting to see the shake-maker's page. They actually funded some of the research - so now I see why liquid food was on the researchers' menu! And (call me a cynic but) it seems a little less surprising that it appeared to give the best results.

Anyway the more info the better!

Dominic

[carorees]

Can you imagine having to follow that diet though? Ugh! The control group who had proper food still lost weight and the discussion implies that had the diet gone on longer the metabolic improvements would have come to the control group too.

Two meal replacements and a proper meal wouldn't bother me, have done that before. On the TV a couple of nights ago was a woman who lost half her 22 stone bodyweight entirely on meal replacements.

The liquid diet folks saw statistically significant reductions in IGF-1 and cholesterol parameters, with a weight loss of 4 kg vs 3 kg loss in the food diet group. I'm not sure there's a strong case for assuming that the food diet group would catch up eventually.

I think it follows that the more strictly you restrict calorie intake the quicker the weight will come off. I also find it interesting that metabolic parameters seem to be proportionate to weight loss. So this says to me that it's the level of adiposity that is causing the metabolic disorder. So essentially you should see improvement in metabolic parameter whatever weight loss regime you embark on (assuming you drop weight).

I think intermittent fasting works but it does so by ensuring calorie reduction, which results in reduced levels of body fat.

[carorees]

Yes, Echo, I think you are broadly right but it does seem from the studies comparing intermittent fasting with daily calorie restriction that the IF regimens favour loss of fat mass and preservation of fat-free mass...which is a good thing of course!

Yeah, IF does seem to show greater proportional fat loss. This does seem good however people who are obese tend to show a reduction in lean mass as their body mass decreases. Due to having less of a load to transport about the work load on the muscles is less. So in a sense they are detraining! So you would expect to see some lean mass reduction in any weight loss regime. I don't think this is necessarily a bad thing.

I do think there is something in IF that is beneficial for health, or else I wouldn't be doing it. I just think it is encouraging that the research seems to indicate that if you are a healthy weight your metabolic parameters will be normal. Therefore you can use weight (or BMI) as a gauge, rather than worrying about fancy, expensive blood tests.

I know Mosley went on about people being thin on the outside but fat on the inside but the research doesn't support this. The research says that your metabolic parameters improve with reduced levels of body fat.

We are focusing here on the dieting side of IF, and that is a valid discussion. But let's not lose sight of the separate (supposed) benefit of IF from the 'repair mode' - this comes not from Dr Varady's research but from Valter Longo and Mark P Mattson. This is the 'big win', otherwise as you say 5:2 is really just another diet, albeit one that is easier for most of us to follow.

See http://crabsalloverhealth.blogspot.co.uk/2012/09/mark-butcher-emails-michael-mosleys.html for some reported comments made afterwards by all the experts on the original Horizon programme - especially Dr Mattson's comments about giving the brain a workout by fasting. This wouldn't apply to a regular diet.

These comments also give a pretty unequivocal answer to the question for 5:2ers of whether it is better on a fast day to eat all the calories in one go or to spread them over the day (sorry, off topic I know).

Dominic

Intermittent fasting has been studied as a weight loss strategy so it is primarily a diet. The effects of IF on people of a normal weight hasn't been studied so we can't assume that IF will afford them the same benefits as obese people.

I think that IF probably is a healthier way to eat in the long run as long as you can maintain an energy balance when you are a healthy weight.