Intermittent fasting--questions for those who've tried it

[invest]

I am starting intermittent fasting with a low/medium carb diet. I'm four days in. I'm wondering if people who are doing it or tried it can relate their experiences:
1. how long have you been on it?
2. what is your fasting routine? (e.g. I am currently doing 20 hour fasts, eating 2 meals between 3 and 7 pm)
3. do you periodically do extended fasts (>24 hours)? If so, how often and for how long? It will be a mental hurdle for me to get past 24 hours.
4. starting vs. current BMI or weight, or % BMI or weight loss
5. how long did it take to get to your current steady state BMI
6. when you are fasting, are you able to get through the day seeing patients or operating with normal performance? I have noticed that for myself, I get anxious (hangry) around 1 pm. Then after I eat at 3 pm, I am drowsy for about an hour.

[8arclay]

Been doing it for a couple years now, eating from noon-6 pm, so 18 hrs. Did it without really realizing it was a "thing", more out of laziness as I never packed or had a breakfast. Keeps me out of trouble with all the goodies in the break room.

Sorry I'm not more help, I don't track anything. I'm a healthy weight, exercise 4-5 days a week, and IF keeps my diet in check. I find towards the end of my fast I actually have more energy, which seems counterintuitive. I need to do a better job of cutting out the refined sugars though

[treesrock]

I think we have passed the point of a fad.

https://www.nejm.org/doi/full/10.105...=featured_home

There was a thread about the book The Obesity Code that supported intermittent fasting, hopefully some of our forum members who had success will answer you question. Personally, I do a 16 hour fast, eating from Noon-8pm. I also don’t track anything as my only goal was “don’t get fat as a new attending”, and so far it’s worked. So has the exercise...

[Lordosis]

I intermittently fast between meals and snacks.

[wideopenspaces]

I don't intentionally do IF but haven't had time for breakfast since residency. So I tend to eat between noon-6. I have friends that do IF. One just eats dinner after work every night. She also does longer fasts, around 24-72 hours. She's able to work out and do her usual routine when she does this. I used to fast 24 hours for religious reasons and always felt like I was dying, so I don't get it. I have another friend with terminal brain cancer who has gone keto with IF to try to improve the success of radiation. He also does longer fasts with no issue but obviously has pretty good motivation to stick with it. He's lost about 20 lbs so far. Like anything, this will work well and be doable for some people and not for others. You might need to play around with your eating schedule and with what you eat. Good luck!

[Cubicle]

I don't have the data points OP requested, but I have done it, I do it when I need to drop weight, & I love it. It works for me. Its very brainless. I don't have to count, calculate, plan... nothing. The less I "cheat" the faster & more weight I lose. I'm usually over-worked during the work day now, so "not eating" is normal. Its even a time saver, I have charts to do, no time to stop & eat. I just roll the "fast" it into the work day from last night's last meal, & don't eat for ~16-18 hours.

My first stint with this was ~2009. I probably average 1-2 runs per year, as needed & wanted (family function, feeling "pudgy"). I'm kinda due so I should probably get serious about it again. I don't follow a specific eating regimen during my eating window; I don't exclude anything in particular, as long as I observe the start & end time, I don't have issues losing weight.

I have no interest or relationship with this guy, website, company, etc... but when I first started reading about intermittent fasting, this guy came up. I read a lot on his site at the time.

https://leangains.com/

During my first run, I went from ~230 pounds to ~150 pound in a little under a year. I did cut out all sugar & most carbs. I was really crash dieting, at least 1-2 days per week less than 500 calories, probably at least once every 2 weeks not eating at all, but I was in school so I was going through biochemistry, physiology etc... so I figured I wouldn't seriously harm myself. Never negatively affected my physically. Blood work was never abnormal. I may have been cranky at times, but commuting to school 2 hours each way, out the door at 5am, back home after 9pm, I was lost in studies anyways. I have been steadily gaining weight overall, but 150 was too low for me. I feel great now, I can climb 6 stories of stairs in the hospital still (like I could when I was a resident), but could stand to drop ~20 pounds to look better. "Next month..."

[pierre]

I've been doing it for close to two years. The only data point I have is that I'm down about 30 lbs from my heaviest weight. Subjectively, i have a lot more energy. I eat low carb, but not necessarily keto. I have have frequently done 48 hour fasts. The longest I've I've fasted I think is 4 days. I plan on participating in a 5 day fast, starting Jan 6th.

I am also a strong believer that quality of food matters. I recently finished reading the book Deep Nutrition by Cate Shanahan. I highly recommend it. Her main thing is that industrial vegetable/seed oils are terrible (and they are in just about every packaged food you can buy). And sugar is also bad.

[Tim]

No science here. Eat 3 times per day.
Something for breakfast- even toast with juice or milk.
Something for lunch - even a ham sandwich
Something for dinner - salad, vegetables and some meat,chicken or fish.
Fresh is best, frozen is next.
No meal needs to be large and if you miss one, snack on an apple or banana.

Treats are treats whether it’s snacks or deserts or sauces.
Eat within 30 minutes of exercise.
Dieting is “easy”, sweat it off. All that is water weight but I guarantee you burned a ton of calories sweating off 10-15 pounds of water weight. To do this means you have to have maintained a modest level of fitness.
No science, just Mom was a dietician and coaches growing up.
Never understood the weight loss/food programs/diet fads.
I do believe in supplements/tilting/vitamins for deficiencies.
What am I missing? Eat right in small portions seems to be logical and works.
Full disclosure: I have no financial interest in Nutrisystem or JennyCraig.

[abds]

1. 1 year
2. skipping breakfast (so eating between noon and 6ish). Keto.
3. no
4. Not sure, probably 10 pounds, but never really kept track as I've always been a good weight and simply did this to cut out refined carbs for a few months and I ended up liking it. My body fat percentage is definitely down but I haven't measured it.
5. 2 months
6. full energy including working out in the AM and surgery all day. The keto aspect may have something to do with this, or maybe not, but that's my assumption since before keto I felt horrible if I skipped breakfast and I also got tired after lunch, which also no longer happens

[Lordosis]

I have actually been thinking about IF for real. However in my mind it just seems like a way to decrease calories just like most other diets. It might be a good way to do it because it has some black and white rules that are easy to follow but it seems that way all the same. I rarely eat before noon already. But I can tell you anything I eat after dinner is probably garbage. So basically this would just force me to eliminate that garbage.
The thing that has held me back is there are several days of the week where it is just impossible for me and my wife to eat before the kids get to bed. So we end up eating at 9 pm or so. That will get better as my kids get older but dinner time for them right now is more of a wrestling/wrangling match.

[DavidGlennCPA]

My wife lost 65 pounds over a year doing IF and she still does about 20 hours a day. She's solidly maintained her new weight.

She read the Obesity Code, as well as Delay Don't Deny.

She would periodically do longer fasts like 36 hours in the beginning. After a few weeks the "appetite correction" kicked in and it became easier to fast.

She has more energy when she fasts rather than less.

[White.Beard.Doc]

I have been able to easily maintain a BMI of 22 with low carb and IF for 19 months. The low carbs put me into ketosis, which makes fasting painless. When I am eating lots of carbs, my appetite is much greater, the ketosis/low carbs simply blunt my appetite.

When my weight gets a bit too low, I try to eat 3 meals a day and allow higher carbs like pineapple, grapes, and occasional ice cream. Now, after a holiday period with no restrictions and lots of goodies, I am up a few pounds above my ideal body weight. Next week I will go back to lower carbs for 48 hours and then do 16 or 17 hours of fasting a day, eating only between noon and 7 pm. Within a week or so I will be back to my ideal body weight.

This regimen has been working very well for me.

[xraygoggles]

I don't follow keto diet, seems too restrictive and I can't do it long term, personally.

But IF is a great way to lose weight while still enjoying life. Most people fast breakfast and eat within a 4-8 hour window after noon. I try to IF during the weekdays and not as much on the weekends for social reasons.

IF + consistent exercise/cardio/yoga/anything active means you can maintain a lean body mass without much effort.

[uptoolate]

I was one of those typical people who inadvertently did IF for many years. Especially once i was an attending. No breakfast or lunch. Simple, no food type restriction and if I had to judge the diet I would have said it was largely 'low-fat' as per AHA/USDA recommendations - not! After I retired I started to eat earlier in the day (of course I was walking much less too) and put on a few pounds but have never been particularly overweight. Lowest mature BMI was 19.2 after a 3 month stint in Africa and post retirement got up to 26.4 now two months after consciously doing IF 5 days a week (eating anything 6 - midnight) I am back at 23.7. I would be happy with 22.1 because that would make me the 'ideal 70 kg man'!

What I need to get busy with is more light weights to maintain strength heading into my 60s. Personally, I think that Dr. Fung and other advocates of IF and low simple sugar/fructose diets are onto something but of course time will tell.

[xraygoggles]

low simple sugar/fructose diets are onto something but of course time will tell.

I don't think we need any more time to tell whether this is a wise move or not.

Sugar is the worst thing you can eat for your body strictly from a health standpoint (maybe a close second to alcohol, but prolly not by much)... any diet that limits simple sugars is a win in the long run.