I am about 3 weeks into a ketogenic diet, following the framework outlined by Volek and Phinney in their books. They recommend that protein is a set amount based on your height and ideal body weight. For me this is around 90g per day minimum. Carb intake is minimized, and for me its less than 20g net carbs (Atkins calculation) per day. Based on this approach, the rest of my energy needs come from fat. If I am active, I eat more fat. The protein and carbs remain consistent as total amounts, not % based.
I have been monitoring blood ketones twice daily and have been in the recommended range for some time now. I may not be fully keto-adapted yet (as they say it can take 4-6 weeks), but I am definitely generating enough ketones to provide adequate fuel for my brain and other organs once my body does largely adapt.
On the 'Ask the Low Carb Experts' podcast a few months ago, Jimmy Moore had Dr. Phinney on the show. It was a long show with a ton of great info, but there was one thing that Phinney said that didn't make sense to me and he didn't really explain.
What he said was that fasting is a bad idea because one will lose lean mass when not eating for an extended period of time. He said skipping lunch might be OK, but he wouldn't recommend going longer than that. There was no real further explanation or discussion on the topic.
Since the context of this show was ketogenic diets, I am under the impression he was speaking of fasting while in ketosis. Alas, I could not tell if his statement was general or specific.
Many people here are familiar with the Lean Gains (18/6) and the Eat Stop Eat approaches, in which you have fasting windows of 18-24 hours, but never actually have an entire day where you do not eat (well for most people most of the time). There are many supposed benefits to this type of fasting, and working out while in the fasted state has proven to conserve and even increase lean muscle mass, not break it down for body fuel.
So what I am wondering is if there is any scientific literature/studies/evidence regarding intermittent fasting while also being in ketosis. Does being in ketosis somehow negate the positive benefits associated with IF, or was Dr. Phinney perhaps making statements unaware of these types of routines?
My thoughts are that if I eat the minimum amount of protein every day, even if I fast for a 24 hour window in between, I will still incur the same benefits as anyone else and will not suffer the loss of any LBM. Additionally, I think the risk of me losing LBM is actually less by being in ketosis, since my body now requires less glucose to function optimally.
If anyone is aware of any studies or research out that proves me right or wrong, I'd really appreciate you sharing. And if you agree or disagree, please let me know what you think and why.
asked byVossman (435)
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on December 14, 2012
at 08:41 PM
I have been IFing for about 3 years...on and off. I train on an empty stomach at 5am. Both bodybuilding and powerlifting schemes. I don't eat a single thing until 1pm. By which usually a double tortilla wrapped extra beans and rice burrito finds its way into me for 1500 calories. then i basically just snack all the way until dinner..which is at 9pm..for another big meal. Then bed. So I pretty much break every rule in the book and still somehow get in shape for contests. Which can only mean one thing...: the rules are garbage.
There are no studies investigating IF on keto that I know of. But if you're worried about LBM breakdown on a fasted regimen, dont. Overall macronutrient intake will rule your goals. Outside of eating just one ridiculously large meal (which I dont recommend) any other kind of eating schedule doesnt make any difference. 6 times vs 2 times vs 5 times vs 8 hours vs 16 hours. Whatever. I do IF because it's immensely convenient. I did it also because i was eating 6-8 small meals every day for 6 years before I discovered two important things.
- I could eat just KFC and still get down to 7% and ready for a show. That's keto...for 22 weeks straight.
- I could eat nothing but low fat ice cream sandwiches, pop tarts, and rice cake, and whey protein and come in just a little above 7% (probably because of the water, but close enough).
Whatever the claims are on IF, I know for a fact that I feel mentally and emotionally better and have better energy for my AM workout on an empty stomach. Rather than stuff myself at 430, then stuff myself again at 7Am then again at 11, 2, 5, 8....etc. Longevity is an absurd claim, as those studies would take 50+ years to confirm, and IF as a theory has only been around for a few. Energy levels? maybe. I dont see much of a change between 16 hours of feeding and 8 as long as I'm eating the same exact amount. I have read all the relevant human research and even some of the animal--although the latter is questionable in its efficacy. I would suggest, treating IF as more of a tool of convenience and freedom, instead of letting it restrict your food protocols EVEN MORE?! How is it that things that are intended to be simple become so complex in their use? Why is it that when we talk about weight loss these days, insulin must be brought up? Sigh. Don't go ranting....must stop myself.
Take it from a veteran of continued weight gain and loss as I do this on purpose every year..somtimes twice a year.
No. fasting and keto are not at all the same thing. I never want to be in keto again..as I think it's one of the most absurd things you could do to lose weight if your'e grossly overweight. It's even pretty absurd for competitive bodybuilders under 10% bodyfat as we tend to get really "flat" on it. So..honestly..maybe for the diabetics. But I know how you feel. When i can only eat 200g carbs a day, I feel like im on keto too.
on December 13, 2012
at 11:12 PM
This is in response to nursling since it would span several comment boxes:
I don't agree with some of your points here. Specifically that LBM is not interchangeable with glucose. The liver and most muscles store glycogen, which can be converted into glucose if your body needs it. If you are glucose dependent and not getting enough carbs (and protein), your liver depletes and then if necessary your body goes after your muscles. This does not happen in one day though.
However if you are keto-adapted your liver glycogen stores have little to nil. In this state your brain and other organs are using ketones for the majority of their fuel, which means that they require much less glucose. So if you are keto-adapted and you do not get enough protein/glucose that day, your body would look to glycogen stores for fuel but it wouldn't need as much as if you were fully glucose dependent.
Next, you say that ketosis mimics fasting. This is not true. Full ketogenic adaptation takes week of restricted carbohydrate intake, at least on initial attempts to switch the body's primarily energy source to ketones and away from glucose. Yes you may generate some ketones if you fast, but that does not make you keto-adapted nor does it mean your body is using those ketones efficiently or at all.
Last, this would not be a PSMF. That type of diet is extremely low in fat and carbs and very high in protein. A well formulated ketogenic diet is very low carb, adequate protein, and moderate to high fat. Too much protein will result in increased glucose levels due to gluconeogenesis. Additionally a PSMF diet does not actually involve fasting, but it does require extremely limited calories.
Additionally I think you missed the fact that I said I would be eating the recommended amount of protein per day. Here is an example
Monday, I wake up and have breakfast at 8 AM. My breakfast has 45g protein and 50g fat and 5g carbs. I have lunch at 1 PM which has the same macros. I do not eat until 1 PM the next day, where I then have 50g protein, 40g fat, 3g carbs. Then I have dinner with roughly similar macros again. So on both days I got the required minimum of 90g protein and ate enough to be completely satisfied. But, I did not eat anything for a 24 hour window between 1 PM Monday and 1 PM Tuesday.
I appreciate you taking the time to respond but I think your understanding of ketosis and fasting is incomplete.
on December 13, 2012
at 09:12 PM
It seems unlikely that this kind of study has been done. So I would recommend testing it out yourself!
I agree with you. Choose the fasting window that gives you the most convenience, least hunger, and best total weight loss. Also you might try "extending" a shorter fast by making the first meal or two fat-only. If this has the effect of bunching your protein up into one or two late-day meals (ideally PWO) then this may be even better.
Personally I spent a lot of time worrying about maintaining LBM and I think it mostly impeded my ability to lose weight. After finally getting some respectable body composition testing, I realized that I didn't even have enough LBM to be worried about it anyways.
Edit: I am skimming Lyle McDonald's "The Ketogenic Diet" now. He does say the goal of Ketosis is to mimic fasting, which you and nursling have debated.
He also says at least some of the glucose your body generates is generated by breaking down protein - dietary protein if it exists else muscle protein. The most important aspect of eating the protein is to prevent muscle breakdown.
Regarding timing, he suggests 30-40 grams post workout. Also he says too much protein at one meal might disrupt Ketosis.
He also suggests much higher protein per day than Phinney, 180g/day for a 200lbs man.
Otherwise, not much here to answer your question so far.
on December 13, 2012
at 10:45 PM
You will lose some lean body mass if you do a full fast without any protein intake, even while in ketosis. It is just because the amino acids your body always needs have to come from somewhere, and if you don't supply them exogeneously via protein intake, your body will break down LBM to get them. I don't see how being in ketosis would make you less likely to lose LBM when fasting, since LBM is not interchangeable with glucose.
Fasting is beneficial for a number of reasons, many of which are achieved by being in ketosis, since it mimics fasting. One benefit you will achieve from full fasting is the rest it allows your digestive system. Obviously if you are in ketosis or doing a protein-sparing modified fast (wherein you only consume the minimum protein requirements and nothing else), then your digestive system is still at work to a degree.
What it sounds like you are proposing is a protein-sparing modified fast. Eating once or twice a day with long stretches in between after keto-adapting is a great way to give your body a long time to rest, reap the benefits of fasting, and put less stress on your body by remaining in ketosis.
but that's all just my opinion