Welcome to The Fast Diet › The official Fast forums › Body › Science of intermittent fasting › Ketosis (Teaching the body to burn fat)
This topic contains 14 replies, has 9 voices, and was last updated by etherial 1 year, 7 months ago.
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20 Nov 13
I have been on the 2:5 for about 6 months and lost about 10kg (over 20lbs) So thank you Dr Mosley!
A lot of the reviews of the fasting lifesyle seem to suggest that it is just a way to reduce average weekly calories, but I’m sure most of you think there is more going on than simple calorie reduction.
During the last 10 days I didn’t fast as I was on holiday traveling and found it difficult. Amazingly I did not gain any weight. This has happend on two occasions during the last 6 months.
I think the fasting days are forcing the body to relearn how to burn fat. I’m a bit confused about the correct scientific terms for this ‘lypolysis’ is I believe the breackdown of fats (into amino acids) and ketosis the burning of
fat as fuel.
What ever the terminology it seems like the fasting days teach the body a long forgotten trick of switching from available glucose derived from what we just ate, to reserves stored as fat.
I suggest that this trait applies to non fast days too, hence the lack of weigh gain during holidays.
I used to do a bit of distance running and am quite familiar with the concept of ‘hitting the wall’. This is when a runner runs out of glucose and has to switch to fat burning (around the 18mile mark). Often that process is difficult, I have had to sit on the ground for about 3 minutes until my legs felt like they would work again.
I’m not running now so I can’t try a quick marathon to see if the diet has helped with the switch.
I welcome your thoughts.
Perhaps Dr Mosely could weigh in on this with some scientific evidence.
I love science and this is why I love the 5.2 as it makes so much sense.
Your body will go into ketosis when fasting for a short time, this is probably why some people get headaches. It will also make you very thirsty and wee a lot as your body tries to flush out the by products from fat metabolism. This is a common symptom of type 1 diabetes but obviously they go into a severe more ketoacidosis due to prolonged lack of insulin and metabolism of glucose and start burning muscle for fuel.
It’s quite complicated stuff but if you google fasting ketosis there’s loads of interesting info online. Michaels book was lacking in any science stuff which is a shame as I think people are interested.
I know that athletes or very fit people are more efficient at burning fat as they are used to it so yes I think the 5.2 does reset the metabolism in a similar way.
I have managed to this this after years of cycling and find I can ride for a few hours on an empty stomach. Always need coffee though !!!
21 Nov 13
I’m also very interested in ketosis. I tried it out a few weeks ago and didn’t eat any carbs for 1,5 week. I lost quite some weight, but felt like I couldn’t sustain it – I started feeling really weak, dizzy, couldn’t walk straight some days and all in all didn’t get the energy boosts some people boast about.
So now I just cut carbs on my fast days and allow myself fruit and yoghurt on normal days – still prefer not to eat rice, noodles, bread and potatoes though. Sometimes a baked good or chocolate pudding as a treat, but not regularly. I do think this really contributes to my quicker than average weightloss (7kg in 3 weeks, of which most during that first 1,5 week).
I’ve also started working out fasted. I do this after work before my only meal of the day, so after fasting for over 20 hours. I do HIIT (Insanity), which combines cardio and strength through bodyweight exercises. So far my results have been worse than when I did the program before when eating regularly, but I’m waiting to see how it goes in two weeks when I do my second fit test. My body is most likely also learning how to switch to burning fat efficiently.
What you said about going on a holiday, this reminded me of the “carb loaders” I know. They basically cut carbs during the week, then they “carbload” on Saturday – eating everything from pizza to ribs to whatever they want. They say that it doesn’t cause them to gain weight, because the body is still in fat burning mode and the glucose from the carbs goes straight to the muscles, giving the muscles the strength to keep working out through the next week. Hence carb ‘loading’. These people are basically in ketosis 3 days a week (it usually takes the body about 3 days to go into full ketosis).
These are all bodybuilder types though, who do mostly strength training so it doesn’t really sound like a great idea for me. I wanna be lean, not buff.
Anyway, long post – gonna head over to the next one 😉
25 Nov 13
Hi Nika and Z
Thanks for your input, we don’t seem to have many other followers, perhaps this stuff is a bit too deep!
I’ll do some more digging and see what I can find on the metabolic demands switching from glucose to fat burn.
I wonder if any in depth study has been done concering what realy happens in the body when we switch fuels?
I’ll post any results I find.
All the best
I found this topic really interesting Rcroix so keep the info coming. When I did the marathon I didn’t hit the wall I think because I’d done my long runs to educate the body in fat burning but that was a while ago!
Nika-I used to work out in the fasted state but don’t now,nothing worse than running out of steam in the middle of a power press!
congrats on ur 20lbs loss!!
we have supermany followers of ketosis on nonfastdays
deep stuff as u say we like deep thinking 😀
look @ the reverse site
or the vids & lectures & tools on this site
everything a newbie/poster might want 2 c, use & read
hope this helps ur journey in this the fdl (fastday lifestyle) w/ ketosis wish u continued success
when u watch the vids of these dr’s & researchers
they point that the reason a mediterranean diet the lowcarb 1 has been applauded is because they fast
happy & nonfastdays & fastdays & 5/2 & 4/3 & 6/1 & adf or 4/2/1 or 3/3/1 or 5/1/1 or adf w/1 & the fdl (fastday lifestyle) & lchf (lowcarbhighfat) 😀
26 Nov 13
Hey Sonunda, I do HIIT with just bodyweight exercises so luckily I don’t have the risk of being crushed by weights should I suddenly slam into that energy wall 😉 Yesterday I found that it’s not really my breathing that’s forcing me to stop, but rather my muscles turning into porridge… From what I’ve read about working out fasted, that’s just the opposite of what other people tend to experience.
It’s a bit frustrating but I guess interesting as well… I’m planning on cutting carbs this week again, totally, and keeping up with the workouts. I really want to give it at least a week because I understand it takes your body about 3 days to go into full ketosis and I’ll just have to push through those days… Not really looking forward to that, but my biggest weightloss so far has been without carbs so I’ll just focus on that!
I read the book “The Paleo Solution” and I liked the ideas, however I did feel like he was doing some major propaganda for his own method rather than having a scientific approach to it. It does explain a lot more about the biological aspects of eating low carb and it basically follows a meal through the digestive track and the rest of the body step by step. Maybe it’s an interesting read for you?
Hi Everyone Martin again.
I have been doing a bit more digging on the fat burn subject. I am getting conflicting information about ‘Leptin’ the enzyme that is influenced by fat levels. One site says that increases in leptin cause the switch from glucose to fat burn but another says that calorie restriction causes leptin levels to decrease, which would contradict our thoughts that the fast days force fat burning.
Whatever the reality it seems like leptin is a key player. Perhaps Michael could chip in with some ideas?
All the best
Hi again. I don’t believe in cutting things out-I don’t especially want my body to go into ketosis. I’ve been following the 5-2 since July,have now lost 10.5Kgs dipping below 70 for the first time for ages. I’ve had no trouble fasting,no trouble eating sensibly on the no fast days and no trouble keeping up my schedule of 9 fitness classes a week. The good thing about this diet is that you don’t have to cut out major food groups like carbs,that would be the Atkins or the dukan diets,neither of which worked for me.This works,so if it ain’t broke don’t fix it.
27 Nov 13
I’ve consistently kept fat intake down on all days. I was talking to a couple of scientist on the weekend and they were skeptical about the fasting days. They had a rethink when I said these days were not consecutive.
This is my 4th week on 5:2 and my clothes are loose fitting.
I will refrain from saying anything to others until I’ve gotten past Christmas.
29 Nov 13
different people try different things. And yeah, you don’t HAVE to cut carbs, but some people just prefer it and are interested in it. You say the good thing about this diet is that you don’t have to cut out major food groups? I think the good thing about this diet is that it’s all up to you how you follow it / plan it. So if you don’t believe in cutting carbs fine, and I won’t lecture you on how bad some carbs are for the human body – just let us discuss our theories here 😉
Martin, I’ve looked up what the Paleo Solution book says about Leptin:
“Leptin regulates both appetite and metabolism. Leptin enters the central nervous system where it acts on receptors in the brain that control energy intake and expenditure. Leptin is produced by white adipose tissue (fat cells), as well as the cells lining the wall of the stomach. The leptin produced by the cells in the stomach is responsible for controlling appetite. When Leptin is working correctly, it’s very effective at telling us we are “full” after eating a meal. As we will see, when leptin signaling (how a hormone “talks to a receptor”) breaks, it is the beginning of problems ranging from cancer to accelerated aging to neurological degeneration.”
“The stomach is an acid environment that plays host to a small amount of protein digestion by the action of acid and the enzyme pepsin. The stomach is really just staging the food for the serious digestion a few stops down the line. Cells that line the stomach sense food and release leptin into the circulation. Leptin passes into the brain, signaling the appetite centers that we are “fed,” thus decreasing appetite, while increasing our metabolic rate in response to food.”
“It should not come as a surprise that our bodies have complex sensors that tell us not only if our blood glucose is high or low, but also how much total energy we have in storage. Leptin, which tells the brain we are “full,” is not only released in response to food, but it is also released from our body fat. This should make sense on a mechanistic level: A relatively large amount of fat will release a relatively large amount of leptin, which sends the signal “I’m full, no need for more food.” Conversely, if we are getting very lean and our energy reserves become low, our leptin signal will be low and we experience hunger.”
“It is also important to note that excessive carbohydrate intake leads to palmitic acid production. If you recall from the insulin chapter, when liver glycogen is full, additional carbohydrate is converted to palmitic acid. This process appears to blunt our sensitivity to leptin, which then inhibits our satiety to a normal meal. This is the beginning of insulin resistance and is at the heart of the mechanism of how we cease to respond to food by feeling “full.””
Okay, that’s all the book said about Leptin. Basically Leptin does not increase fat burning, it’s just something that tells us we are full. It is released by fat stores in our body, as well by our stomach lining when we eat. Anyway, I won’t repeat what has been said above, you’ve read it so I guess it’s clear what the book thinks 😉
14 Jan 14
I applaud everyone here. You are really dedicated and the pounds seems to be coming off in large numbers, too. I’ve lost 14 lbs., but haven’t stepped on the scaled for 2 weeks. I’m scared that I’ve gained since I’m not very consistent right now with my workouts, but then again, I always go through that inconsistency when I either get sick and need to convalesce. It’s a little hard getting back into my routine, but eventually, I get there.
I’m curious about your large weight loss by cutting out carbs on fast days. I’ve also noticed that Dr. Moseley did not have carbs for breakfast in his film. He only had ham & eggs. Hummmm…
I forgot, but in the film, was that his only meal of the day or did he have dinner that evening? I’ve changed my fasting routine a little to just having the one meal in the evening and staying busy during the day and drinking water and black coffee. Mimi (the co-author) ate 6 small meals during the day and you can see how slim she is.
I’ve been on the plan since March 2013, and was hoping to see more weight loss by March 2014. I’m not sure what to do. Any suggestions?
@ethereal, when you cut out bread, pasta, rice etc you haven’t cut out all carbs from your diet, you have just cut out the processed crap. As Nika points out in Paleo/primal eating you are still encouraged to eat plenty of fresh seasonal fruit and veg. These are carbs!
You may have to play around with your diet and see what works for you. When you do cut the processed foods from your diet you will notice some withdrawal symptoms because of their high sugar content. Stick with it, your body is so much better off without that crap.
For what is worth, my recent reading seems to state that the body doesn’t burn stored fat when there is insulin in the blood stream, so on the fasting days, having fewer of those spikes, gives the body a chance to burn fat – weight. With that and the reduced calorie intake over each 7 day week it explains the weight loss. And it sounds good for the body.
15 Jan 14
Thanks. I needed that!
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