Lose weight using intermittent fasting

Do you want to lose weight? I’m currently updating my page with the most important tips on How to lose weight. The page is structured so that you can start at the top with tip #1 and then keep going as long as you like – perhaps you only need one or two of them.

Today it’s time for a new piece of advice at number 14. First a quick recap of all the earlier tips:

Choose a low-carb diet, eat when hungryeat real foodeat only when hungrymeasure your progress wiselybe patientwomen: avoid fruitmen: avoid beer, avoid artificial sweetenersreview any medicationsstress less and sleep moreeat less of dairy products and nuts… and supplement vitamins and minerals.

So there are many things to consider before moving on to this thing, but don’t let that fool you. This is one of the most effective weapons available to lose weight. It’s perfect if you are stuck at a weight-loss plateau despite “doing everything right” – or to speed up your weight loss.

Use intermittent fasting

This super weapon is called intermittent fasting. It means exactly what it sounds like… not eating, during a specified time interval. Here’s how to do it:

Recommended first option – 16:8

Probably the most popular option is fasting for 16 hours (including sleep), which is usually easy to do on an LCHF diet. It only requires trading breakfast for a cup of coffee (or some other non-caloric fluid) and having lunch as the first meal of the day. Fasting from 8 pm to 12 noon – for example – equals 16 hours of fasting.

Of course there are many other variants of intermittent fasting, but this 16:8 method (16 hours of not eating, 8 hours of eating during a day) is the one I recommend as a first option. It’s effective, easy to do and does not require counting calories.

You can do a 16:8 fast as often as you like. For example twice a week, or on weekdays only… or every single day. The more often you do it, the more effective it is.

In fact on an LCHF diet some people spontaneously fall into this habit, as their appetite is reduced (see weight loss tip #4, eat only when hungry).

Other kinds of intermittent fasting

There are many other options. Basically the longer periods are harder to do but more effective. Here are two more common options:

  • Fasting for 24 hours (often dinner – dinner) once or twice a week. Effective and can be surprisingly easy to do, especially on an LCHF diet.
  • The 5:2 diet. Eat as much as you need to feel satisfied 5 days of the week and then eat calorie-restricted on two days (500 calories per day for women, 600 calories for men). I don’t recommend this as it requires calorie counting and extra planning, but some people still find they enjoy it.

What about eating when hungry?

Doesn’t advice on intermittent fasting contradict the advice to eat when hungry? Yes it does, somewhat.

I recommend eating when hungry as a first option, and I recommend always eating until you feel satisfied at meals. But if this is not effective enough then intermittent fasting is a very effective addition. Remember – and this is crucial – that between fasting periods you’re still supposed to eat until satisfied.

Intermittent fasting is not the same thing as obsessively counting calories and starving yourself 24-7, i.e. “caloric restriction as primary” (CRaP) diets. Starving yourself is a recipe for misery and failure.

Intermittent fasting is about eating all that your body needs… while still allowing it to sometimes briefly rest from constant feeding.

What’s acceptable to drink during fasts?

During a fast you can’t eat, but you should definitely drink. Water is the drink of choice, but coffee and tea are also great options. During longer fasts it can be wise to add a little salt too, or drink bouillon.

Anything you drink should ideally be zero calories. But it may be acceptable to cheat by adding a small amount of milk in your coffee or tea – if you absolutely need it to enjoy your drink.

What to eat between fasts

So what should you eat when you are not fasting? Well, if your goal is to lose weight I suggest following all the tips above, including eating an LCHF diet. Combining this with intermittent fasting is a great combination.

On a LCHF diet your hunger is reduced and it’s much easier to do a period of fasting. Also, your fat burning is already very good – so when fasting you’ll easily burn lots of fat.

So, while on an LCHF diet the fasting periods become both easier to do and more effective. 1 + 1 equals 3.

Who should not do intermittent fasting?

Intermittent fasting can be a great idea, but not everyone should do it:

  • If you are addicted to food or sugar then intermittent fasting will increase food cravings and increases the risk of a relapse… so be very careful. I recommend always eating when hungry.
  • If you are totally stressed out or sleep deprived then take care of that problem first (see weight loss tip #11) or fasting may be too stressful for your body.
  • If you are on any medication – especially insulin – the doses may need to be adjusted when fasting. Discuss it with your doctor first.
  • Growing children, pregnant women and breastfeeding women should not do longer fasting periods, as they have an increased need of nutrients. I recommend eating when hungry and using the 14 tips above if you need to lose weight.


For more on fasting check out our material with our top fasting expert, Dr. Jason Fung:

What is Fasting? – Dr. Jason Fung
How to Maximize Fat Burning – Dr. Jason Fung
How to Fast – The Different Options – Dr. Jason Fung
The 7 Benefits of Fasting – Dr. Jason Fung
The Top 5 Myths of Fasting – Dr. Jason Fung
Breakfast! Is It Really That Important? – Dr. Jason Fung
The Perfect Treatment for Weight Loss and Diabetes – Dr. Jason Fung
Ask Dr. Jason Fung

All 18 tips about weight loss on the page How to Lose Weight.
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  1. Michael Smith
    I assume that bullet proof coffee wouldn't be advised during the fasting period. Is that correct?
    Reply: #2
  2. Dr. Andreas Eenfeldt, MD Team Diet Doctor
    Yes, absolutely. That's way too much calories to be considered fasting. ;)

    Bullet proof coffee fits better under tip #16.

    Reply: #15
  3. Ffflux
    could you write some posts on lchf while breastfeeding ? :)
    Reply: #45
  4. Cornelia
    I have been doing Dr. Fung's 24 hr fast every other day for several months. I had been very low carb and did not lose weight but since starting the 24hr fast I have lost 25 lbs. Also all of my lipid #s have come down as well. I will continue as long as it takes to be a health weight and beyond to maintain.
  5. Karen
    I am a female and have found it best to do a 14:10 fast with bulletproof coffee breaking the fast.
  6. Vytas
    Does fasting at night make insomnia more likely? For example, having breakfast and lunch and then skipping dinner and making the next meal breakfast the following day.

    I eat very little fruit but enjoy a half of an apple and a few berries with herbal tea about twp hours before bed. I "seems" to help me sleep as opposed to not doing so. Of course, that's purely anecdotal.

    Reply: #16
  7. 1 comment removed
  8. palo
    Dr, Varady's every other day diet, you eat 500 calories on diet day and anything you want on alternating feast days, is supported by lots of scientific research and has proven to be highly effective, specially when combined with LCHF.

    Learn more here: https://www.facebook.com/TheEveryOtherDayDiet

  9. Lisa
    I am a type 2 diabetic. My question relates to the Dawn Phenomenon. My BSL's rise and rise until I eat. I noticed this when I was doing 16:8. Should I attempt a 24 hour fast?
  10. ron stone
    why is it that capitalistic folks like to co-opt a eating plan like Leangains by Martin Berkhan and pretend that this 16/8 plan is their creation???

    At least Jason Fung credits Berkhan but others(like the guy who runs this web site) conviently avoid giving credit,

    Replies: #12, #13, #14, #46
  11. Eric
    What are the consequences of every other day fasting versus five consecutive days done once a month.

    I think the answer is we do not know.

    The Valter Longo research indicates observable results like wbc count and stem cell growth from the give consecutive days that seem more than what is achieved with eod

    Either added to hflc seem to produce great results

  12. Murray
    Who cares who popularized something first? One can bet numerous cultures homed in on similar principles and embedded them in rituals. Many religions have fasting rituals. What matters is whether fasting works, different ways in which it works, and why it works.

    I don't understand the reference to capitalism. Are you suggesting the way intermittent fasting is being presented is breaching intellectual property in the idea? Isn't copyright (property in the expression of ideas) the epitome of capitalism?

  13. Caroline
    Why even bother writing that comment? Not remotely constructive. And to call someone 'that guy' when you know his name, just plain rude.
  14. Garry

    Right, of course. Leangains "invented" 16/8 intermittent fasting. /sarc

    Would it be copyright infringement to suggest 15/9 or 17/7 intermittent fasts? Does Leangains have copyright on those as well?

    And then there is the entire concept of "fasting." Does Bill Gates or Elon Musk own that one?

    Reply: #213
  15. Garry
    After 7 months LCHF I became interested in Jason Fung's approach to fasting, courtesy of previous posts on Dietdoctor.com.

    I'd had initial success on LCHF with a 50 pound loss over 3 months, but followed by a multi-month stall. Also some odd things such as fasting glucose inexplicably going from a normal 80-90 on LCHF to 100-110, and little improvement in resting BP of approx. 140/80.

    So I did a 6-day fast last week and am presently on the 3rd of 4 days this week. BP has reduced to ~125/80, fasting glucose back to ~85-95, and a loss of about 10 pounds (I think all fat loss since I'm longtime keto-adapted and there was zero weight regain on resuming LCHF for a couple days).

    I'm in experimental mode so I'll be trying different periodicities, and probably some longer fasts as I become adapted to this practice. The combination of LCHF and fasting seems very effective.

    Reply: #64
  16. Ctdsjsu92
    I have trouble sleeping when on a 24 hour fast. The solution is to fast from dinner to dinner. That way you don't go to bed hungry and the energy surge does not hit until the 2nd day.
  17. Chris D
    Great to see this article on dietdoctor. I have found that often when I skip breakfast or lunch, the hunger I experience and my meal size at dinner is usually not effected whether or not I had breakfast or lunch. A benefit often not discussed is that by consuming one big meal rather than spreading them out into smaller meals, you keep your leptin and thyroid levels elevated while consuming the same number of calories (sorry I used the c word). I usually use 16:8 during the week and eat 3 squares on the weekend. Good luck!
  18. LeeAnn
    Andreas, I have heard on several podcasts that IF is not as 'helpful' to women as once thought. Will you give your opinion on this?
  19. Rita
    Ha ha, does this mean, as a woman, I can drink all the beer I want?
  20. nancy
    Ha @ Rita, that's what I thought. IPA, here I come! I find I don't even get hungry til 1-3pm since I started HFLC.
    I started about 18 months ago. Somehow my good side effects, like decreased IBS problems and restless legs syndrome have started to come back, racking my brain wondering why?
    Weight is still good.
  21. Mary Titus
    Hi. I am a 58 years old. I have been doing IIF since I turned 50. I have been doing LCHF for 15 years. I can't imagine living a fasting lifestyle without a low carb high fat menu. IF works so well for weight loss that I consider it to be my weight loss diet. However , i just eat once a day normally. When I need to lose weight I just give my fasting a kick in the ass. This week I did a 3 day fast and I lost 4 lbs. I had intended to end the fast yesterday, but since i was not hungry, i decided to extend that another day. I will break the fast tonight. but I intend to fast again on Friday. I do halfassed burpees daily . when I eat I see to it that my meals are LCHF nutrient dense so that it can see me through another fast.
  22. Don in Arkansas
    I am beginning a regimen of IF. I am shooting for the 24-36 hour range to start. You mention that if you are addicted to food or sugar that fasting is not the best idea but wouldn't the best way to beat an addiction be to stop the addictive substance? I'm not addicted to sugar (thank God) but I am guilty of chronic overeating.
  23. Joanne
    I started LCHF in May of 2013, and 25 months later had lost only 20 pounds. LCHF suits me, and keeps my hunger low, so it's been easy to persevere, although with much frustration at not losing much weight. Last December, I got a Ketonix breathalyzer from Sweden. It tells me that most days I am in the red, top level of ketosis, some days in yellow, very few in green, and never in the blue. That is heartening, even though red-level ketosis does not mean weight loss. At the 1st of June (2015), I began Intermittent Fasting after watching and reading Dr. Fung. 1st week, did a 24h fast. It was like nothing, too easy. 2nd week, did a 48h fast, again like nothing, so I extended to 72h. Nice feeling of lightness and a calm energy. 3rd week, did another 3 day fast, but didn't take my supplements, and felt a bit queasy, so that became a 70h fast. 4th week, now actually, doing another midweek 72h fast, with supplements. Going well, very doable. Bottom line, I have lost a total of 9 pounds in the month of June. I'm way impressed and feel I've gained some control over my weight loss. I expect to drop below 200 lbs this week. So happy I could spit.
  24. Sandie
    Joanne, congrats on your success. Can you list which supplements and the dosages you're taking. My 64 yr old sister is big into supplements and she might consider doing this knowing that she can still take them. Thanks so much.
  25. Joanne
    Reply to Sandie: Cod liver oil, 2.0 mL; magnesium, 300 mg; potassium, 99 mg; berberine, 1,000 mg; grape seed extract, 300 mg; Life Extension Super K with K2 complex, 2200 mcg; Bob's Red Mill potato starch, 4 tablespoons in a large glass of cold water. All once a day. For the IF, I added a half-cup of chicken broth and added extra sea salt to the large glass of cold water. Note above, Adreas' suggestion to add salt to longer fasts. Interestingly, I've noticed for some time that the potato starch (resistant starch) does not affect Ketosis, and now it does not seem to affect IF weight loss.
  26. BobM
    I too am performing IF (intermittent fasting). I've been on a LCHF diet for about 18 months. I lost 20 pounds quickly, and felt great, but I stabilized at that weight. I was eating 5-6 times per day. I think I was slowly losing weight, as my pants were fitting better. However, I realized that I had a high fasting blood sugar level even though I'd been on low carb for 6+ months. I did some research and determined I was insulin resistant. I stumbled onto IF first, and then found Fung's website. I started skipping breakfast two days per week. Then I started skipping breakfast and lunch two days per week, then one day without eating and one day with skipping breakfast and lunch. Then a three day fast. I've been trying some longer day fasts with 16:8 (I usually don't eat breakfast any more) and partial or single day fasts. In about 5 months, I've lost almost 20 pounds. I also try not to snack, although if I'm really hungry, I will break that rule. If I do snack, I try to make the snack be high fat or low insulin-causing if possible. I also don't stress about things, and if I have breakfast one day, it's not a big deal. If I go on vacation, I may eat more.

    So, I'm LCHF + IF. I plan on trying a longer fast (a week) to see what happens.

    Side effects of IF for me: I run hot and cold during the day and at night; refeeding after a longer fast causes some bathroom issues. Otherwise, I'm fine.

    I find IF freeing. I no longer have to eat breakfast, and can get to work earlier. If I'm busy for lunch, I just don't eat it. I've learned to deal with "hunger" (meaning stomach rumbling). I actually prefer not eating breakfast after my morning workouts.

  27. BobM
    Oh yeah, another side effect is lower leg cramps. I have to take magnesium for that (potassium and salt don't seem to cure these, although I add these to a drink too). I drink coffee+cream, various teas, and bone broth (stock) on fasting days.
    Reply: #33
  28. Eric
    @ Garry no. 15
    I find by blood glucose drops to 65 within 36 hours of fast and on the 5th day drops to 55 which I use to indicate that 120 hours is enough to reset my glucose, insulin and ketones.

    How often? Once a month, once every 3 months, twice per year?
    I am not sure we have evidence to support and frequency or time period as THE optimal. Time may provide better markers.

  29. JoJ
    Dr E,
    I'm prediabetic, feel like a sugar addict and feel deprived when I go long on the HCLF diet. (I have four kids so plenty of fruit and peanut butter around.) Had some success last year, but now I just cannot string more than a few days together. And I cannot sleep on an empty stomach. What's wrong with me?
  30. Peter Burban
    I have been fasting for some time however my stomach is growing larger than ever why ?
  31. Eden
    I am on Dr. Fung's IDM program and we do bullet-proof drinks on his fasting program. I actually do bullet-proof Crio Bru (roasted cocoa bean drink) and it has helped a lot for me especially on longer fasting periods. I will be forever indebted to you Dr. Eenfeldt for introducing me to Dr. Fung's information on obesity and IF. I have been doing low carb too for a while and my blood sugar readings were getting lower but I have had insulin resistance for a long time and I could not seem to drop in the normal range as fast as I wanted. With IF, I am getting readings of 84! It makes me very hopeful and excited for healing the inflammation in my body and losing weight.

    Your website has been invaluable. I joined the membership program because I found you offered such great information for free that I wanted to know more. I am especially intrigued to learn more from Bitten Jonsson and her work on sugar addiction. There is so much incredible information here that I do not feel so alone in my fight to gain my health back. I have refused weight loss surgery for several years hoping to figure out how my body works. I feel like I am finally getting a complete picture of how to eat. Intermittent Fasting has been a lifesaver to get my weight to budge and drop my blood sugar readings to normal range. I lost 15 pounds in just the last two weeks with it. Thank you!

  32. Nizam S.
    As a muslim,the idea of fasting really isnt new as we muslims fast for 1 whole month during ramadan (coincidently I am fasting today).Its just that over the years as I become overweight plus the standard HC and HF diet really took its toll.I always feel bloated and nausea after big meals thus making it very difficult to fast.But now as I am practicing LCHF,my stomach feels very calm and fasting is becoming very easy to me although muslim fasting is very strict where we dont eat and drink from sunrise to sunset.Surprisingly I would get away everyday with very little food without feeling very hungry.My thanks go to everyone who worked hard researching and promoting LCHF...kudos..
  33. Chris D
    BobM, I had those same issues; #1 cold hands/feet, #2 cramps and/or muscle spasms (+ brain fog), #3 bathroom "issues." #1 is from low thyroid and adrenal fatigue, eat more carbs from paleo safe sources such as fruit, sweet potatoes, etc. IF will increase your tolerance to carbs and in my opinion, requires more carbs than regular LCHF without the fasting. #2 you got it: mineral depletion. I take a calcium/magnesium/zinc (CMZ) and potassium supplements daily. Caffeine will exacerbate this problem so if you drink coffee or tea, keep these up. #3 is poor gut biomass. Eat more yogurt and fermented foods daily. Except for yogurt and keifer, we can't buy fermented foods in the USA that are not pasteurized i.e. dead. I make my own fermented vegetables that I keep in the fridge and eat them daily. Look up lacto fermented vegetables on the web. Once you get the technique down they taste great, kill your appetite, and your bottom will thank you. Good luck.
    Reply: #35
  34. Jaideep

    You mentioned that IF and an LCHF diet combined together is an excellent way to lose weight.

    I have been thinking of following The Keto Diet for losing fat which is a type of LCHF diet, as you well know. But I was advised NOT to do Intermittent Fasting while following the Keto diet as it could have an adverse impact on my health.

    What are your views on this?

  35. BobM
    ChrisD, thank you for the comments. I'm not sure I can do fruit quite yet (most fruit causes me spikes in blood sugar and cravings). I can do some sweet potatoes and the like, though. Oddly, sweet potatoes don't seem to affect me much, although I also don't eat much of them when I do eat them. I've been trying to up the minerals, and I'll keep doing so. On the days I don't fast, I've been trying to have yoghurt or sauerkraut (not heated, with probiotics) with each meal, but sometimes I forget. I'll try to be more cognizant of these, once I get back from vacation.
  36. Eric
    Who advised you.
    What is your Keaton's blood sugars how long and hat type of fast? Water only bone broth medical fast like Longo's?

    I s the intents to lose weight. Control glucose and insulin
    Refresh immune system and healthy life span?

    Answer these questions and you go a long way towards answering you own questions.

  37. Steve
    I've been eating LCHF for about 2 months now and I find that I just fast whenever I feel like it or when I'm busy. The thing that I find is my mental clarity with this way of eating is really great and when I go for a day or so without food that doesn't really change. Another interesting thing that I've found is that after going without food for an extended period I still end up eating the same size meal rather than a larger one when I have my next meal.

    I sometimes have breakfast on a Friday, work all day in my acupuncture clinic, go to our restaurant and work until 10pm, go home, sleep well, get up and drive to the markets to get supplies and then come home and cook something around 2pm in the afternoon....I guess that's about a 30hr fast, I don't think I could have done that with ease on a high carb diet I previously ate.

  38. Deborah
    "Doesn’t advice on intermittent fasting contradict the advice to eat when hungry? Yes it does, somewhat."

    I found that IFing (12, 18, 24, 36, 48-hour fasts and a 1-week fast) is a fantastic way of learning what true hunger feels like and how bone broth can stave it off. Once I make it past 25 hrs, my hunger is completely gone. If I ever get lost in the wilderness, rather than rationing food so as to spread tiny amounts over a long time period, I'll just eat meals until the food is gone and then just drink water!

  39. Caroline
    I have been doing 16:8 for about 6 weeks and it has been really easy to do. I give credit to DietDoctor.com for letting me know about it as I would never have known otherwise, this was the first time I considered doing a fast as I thought it would be a nightmare for me, I thought it was one of those crazy things people do when they are trying to lose weight, but with all the information I have been reading and watching I know it's healthy and not crazy! I love the fact that my clothes are so loose and I don't feel I am missing out on anything by not having breakfast. Being in New Zealand it's fantastic that you have this website for people all over the world, Thanks again!
  40. Tamara
    is canned veg okay also lunch meat spam turkey deli or ham
    Reply: #41
  41. Chris the Barbarian
    Okay, maybe. But LCHF is all about real food! Get fresh local vegetables, fresh fish, poultry, meat from local Butchers/Fishermen, look out for a farmer's Market in your Area.

    This is so much better than canned food, and the difference in taste is huge!

    And cured/processed Meat is really not the healthiest way of eating ;) (Discussed here: http://www.dietdoctor.com/why-meat-eaters-get-colorectal-cancer-more-...) Don't cut yourself short of the main benefits of LCHF with "easy" convenience food.

  42. Eric
    Why not five day fasting once a month.

    Most doctors recommend medical supervision.

    I have read a range of protocols from water fasting, broth, too prepared foods like Walter Longos l nutra vegan five day package.

    I do bone broth with one or two fried eggs
    Two on day one 27 grams protein and one on days 2 to 5
    With less broth 17 grams protein days 2 to 5
    Small carbs from egg and added seaweed
    Days 6 to 30
    I ai. For 200 grams fat, 90 grams protein and 18 grams carbs
    Sometimes high sometimes low but average aim is 2400 calories for 25 days and 400 calories for each of the other five days
    60,000( 25 times 2400) and (5 times 400 is 2'ooo) so less than 63,000 is under 2100 per day average to aim for 175 pound weight. 6 ft tall
    Not bad for starting over 360 pounds

  43. Eric
    Weight at end of last five day fast was 177
  44. 1 comment removed
  45. Kdream34
    Why would he write an article while he breast feeds? ?
  46. Suzanne

    My cousin began to gain weight during his freshman year of college. A professor recommended he eat within a window of five hours a day, then widen the window after goal weight is achieved. He's 64 years old now and has maintained a Noon to 8:00 p.m., three meals, eating schedule ever since.
    He's healthy, sharp and active and a bit too thin to my liking. So IF is not a new concept. Also, my great-grandmothers knew 'starches' made you fat.

  47. Randy
    Is one beer a day ok during the intermittent fast? I work. 230-11pm. I plan on trying the fast from 7pm-1pm. When I get home from work i like to have one to mellow out a bit. Thank you.
  48. amir jalal
    Is one beer a day ok during the intermittent fast? I work. 230-11pm. I plan on trying the fast from 7pm-1pm. When I get home from work i like to have one to mellow out a bit. Thank you.
  49. Pawa
    Hello and thanks for the informative article. Is this method also recommended for people who have a rather sluggish metabolism? Because I was advised to rather eat 5 small meals a day so my metabolism always has something to do and doesn't go down. Online I read it is advised to only have 3 meals/ day with no snacks so the blood sugar doesn't spike all the time. Both make sense and fasting sure makes sense too because the body needs to keep running on some energy, right? So I'm a little confused, could you help me on this? :)
  50. Kathy
    I'm still having trouble getting past a plateau. I'm around 20 carbs, eat moderate protein and fat, fast 23:1 about 3 times a week and a 48 hour fast 2-3 times a month. I never lose weight on the 23:1 fast, and maybe 1-2 pounds on a 48 hour fast, but it all comes back the next day. I eat lightly coming back from the fast, and am following all the protocols mentioned here. I think I can do a longer fast, but I'm seriously worried that my body will keep adjusting its metabolism lower (I know there is evidence that says that doesn't happen, but obviously something isn't working for me). Can your body keep adjusting to longer and longer fasts?
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