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. Richard
    You can fight nutritional science and lose weight with the LCHF fad but my goal is long term health so I consume whole plant-based products as the long-living population in the Blue Zones and my weight has stabilized in the correct place.
  2. gbl
    What are the "Blue Zones?"
    Reply: #53
  3. Peter Biörck Team Diet Doctor
    Blue Zones is a concept used to identify a demographic and/or geographic area of the world where people live measurably longer lives.


    What are the "Blue Zones?"

  4. gbl
    Cool. I see one area is religion defined, two some value of Mediterranean, one Norsk (or Sami?) and one other a rice culture.


    Thanks Peter!

  5. 1 comment removed
  6. gbl
    Looking at a map I'm going to guess all those peoples were primarily fishers. What do you think?
  7. Happy!!
    I accidentally thought I created this diet... In embarrassment when people asked me how I lost 60lbs in 3 months (lower than I was in high school- at 150lbs 5'10"!) I thought I should google how it happened and came across this page. I get a lot of evil looks being a nurse in an ER breaking all of the diet rules but this just seemed so much easier to me than Atkins, weight watchers, etc... I have to say I splurge on Creamer and milk with my coffee and it has never made a difference. On my best highest metabolism days I felt like I ate so so much for dinner and would step on the scale and continue to notice weight loss rather than gain and be in shock!!! But I do have one question, a doc looked at me and said "wow you are really doing everything they say not in, in fact they say that's how sumo wrestlers gain weight". Any thoughts?? She is right but obviously their caloric intake is super high but otherwise kind of mimics when this diet suggests eating???
  8. Neh
    I generally workout in morning and take MCT oil and coffee pre workout and whey post workout. I cannot follow the 16:8 if I eat in the morning have to finish by 5 pm. So 3 weeks I stop eating at 10 am, fast ill 6 pm and complete the remaining macros after 6 pm. like 8:16. Does this cycle work? The last week workout in the morning without whey and MCT oil and follow 16:8 completing my macros from 2 pm to 10 pm. Any recommendations...
  9. Håkan
    Hello everyone!

    I have a question regarding intermittent fasting and LCHF.

    Currently doing dinner to dinner fasting and it feels great! So great infact that im doing it every single day.

    Im worried that only eating dinner once a day is going to lower my daily energy needs, similar to how low calorie diets can.. slowly putting my body into starvation mode.

    Is it better to do it only twice a week and then eat regularly (LCHF) ?

    Kind regards,


  10. Chris M
    Most important thing to remember is when the body thinks it's "starving" it WILL slow your metabolism down and seek energy from muscles first as opposed to fat as the body is in defense mode and is thinking it's in trouble. Weight will come off but especially without exercise it will be mostly muscle and then eventually it will use fat as energy. Another non calorie counting way is to eat 6x a day, big breakfast, snack, medium lunch, snack, dinner and a snack preferably 3 hours apart and no carbs after 6 pm.
    Reply: #61
  11. Adam
    Studies show that you don't lose muscle when fasting. What you are stating is a common misconception. When fasting growth hormone goes up and you preserve muscle.
  12. 1 comment removed
  13. Michael D
    Why are Doctors always giving nutrition & diet advice? They have a medical degree not a dietitian degree. They take one class if that in medical school know they feel they are certified to give nutrition advice. It just does not make sense.
    Reply: #72
  14. Liza
    Dr Fung says that the body will find 'homeostasis on any regime eventually, so its best to shake it up and do something different if you stall again. Longer fasts, or maintaining for a while before starting fasting again
  15. Akshay Gohil
    I want to try the 16:8 diet but I can't really understand the whole concept

    I mean how shall I go about with it. I understand that I need to keep an 8 hour window to eat, but I need to ask what can I have in this 8 hour window

    I start with tea/ coffee. Is it supposed to be only black or green ?
    At eleven do I have anything mentioned in the list ?

    If I can be explained I would understand​ it much better

    Replies: #66, #68, #69
  16. Wiki_God
    Eat 1-9 pm macros should be per your weight and before or after that only drink water but if you are super in need of something to much on you can eat a cucumber or pickle. The calorie count shouldn't be more than 10-30 every hour or so. This way you don't break your fast.
  17. Christina
    I try to have dinner at 5:00 but occasionally I have a small snack at 9:00 like a couple rice cakes and a piece of cheese. Does this mean I can't eat till 1:00 the next day or does a small snack count?
  18. Rebecca
    I’m having the same questions. What can I eat during the 1-9 hours?
  19. Peter Biörck Team Diet Doctor
    Hi Rebecca and Akshay Gohil!

    We have tons of recipes on this site all that should be OK to eat.

    Tea (black and green) and Coffee is OK.

    I’m having the same questions. What can I eat during the 1-9 hours?

    I want to try the 16:8 diet but I can't really understand the whole concept
    I mean how shall I go about with it. I understand that I need to keep an 8 hour window to eat, but I need to ask what can I have in this 8 hour window
    I start with tea/ coffee. Is it supposed to be only black or green ?
    At eleven do I have anything mentioned in the list ?
    If I can be explained I would understand​ it much better

  20. Russ
    interesting - for some I sleep from 10pm till 7.30am so fasting from 6pm isn't overly hard and should be fairly easy. evenings sugar cravings eg biscuit tin might be tempting
  21. Russ
    5pm till 9am or 6pm till 10am trial - missed that off
  22. Peter Phelps
    Michael D
    Maybe because the bulk of nutritionists give sub standard information that is not supported by science.
  23. 15 comments removed
  24. Peter Phelps
    Michael D
    Maybe because the bulk of nutritionists give crystal clear information that is supported by science
  25. 5 comments removed
  26. Suicide diet
    Dietdoctor quit taking down my posts and only leaving up positive ones. I'm just trying to keep people from getting very sick or dying,

    Starvation ketosis

    when hepatic glycogen stores are exhausted (eg after 12-24 hours of total fasting), the liver produces ketones to provide an energy substrate for peripheral tissues.ketoacidosis can appear overnight


    Ketoacidosis is what happens when ketosis goes too far. Ketones build up in your blood, and it becomes acidic. Ketoacidosis can cause a coma or death.

    Starvation mode


    Please read this:


    Reply: #96
  27. 1 comment removed
  28. Dr. Andreas Eenfeldt, MD Team Diet Doctor
    Suicide diet,
    That's simply incorrect. Ketoacidosis hardly appear overnight, and shorter fasts (e.g. 16 hours or even 1-2 days) are very safe for people of normal weight or higher, and without certain pre-existing conditions (see guide above).

    If it was not so safe major religions would not have been able to recommend intermittent fasting for thousands of years to hundreds of millions of people (perhaps billions) without any apparent major harm.

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