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.


Top comments

  1. Caroline
    Why even bother writing that comment? Not remotely constructive. And to call someone 'that guy' when you know his name, just plain rude.
    Read more →
  2. 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?

    Read more →
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All comments

  1. Suzie
    Can I mix this up? I’d like to
    Sunday 7pm - 24 hour fast til 7pm Monday
    Eat dinner 7pm Monday
    Monday 8pm start 16:8
    Continue to Saturday
    Saturday 12noon - Sunday 7pm no fasting

    That would mean 1x24 hour fast a week and 5x16 hour fasts with 1 period of 31 hour period of no fasting

    What do you think?

  2. Anneleen
    Can I drink water with apple cider vinagre and/or fresh lemon juice in it while fasting?
    Reply: #203
  3. Peter Biörck Team Diet Doctor
    Hi Anneleen!

    if you use small amounts it shouldn't affect that much. But why take this while fasting?

  4. rachel
    I usually have dinner around 5.00pm I work early so I dont eat till 8.20am what should I eat to break the fast
    Reply: #205
  5. Kristin Parker Team Diet Doctor

    I usually have dinner around 5.00pm I work early so I dont eat till 8.20am what should I eat to break the fast

    You can eat any meal that you prefer that is low carb and high fat for best results.

  6. Roma
    Would like to know if I fast for 16 hours ,what food do I eat later ? M I supposed to follow a diet ,can I do it regularly?
    When will I know I need to stop?
    Reply: #207
  7. Kristin Parker Team Diet Doctor

    Would like to know if I fast for 16 hours ,what food do I eat later ? M I supposed to follow a diet ,can I do it regularly?
    When will I know I need to stop?

    In general, fasting works best when used in conjunction with a keto/lchf way of eating. You can break a fast with any lchf meal.

  8. Evil Fluffy
    8:00 p.m. to noon is not four hours. What are you talking about?

    8:00 p.m. to midnight is four hours.


  9. Nancy Bauer
    I started the 8/16 fast 3 days ago I can feel it already I had weight loss surgery 3 and 1/2 years ago lost 115 lbs from 286 to 180 today I saw 177 so 2 lbs in 3 days I love this I can't eat big meals anyway and I eat low carbs high protein so meals are small but I have my snacks to .this will work for me ty so much .
  10. 1 comment removed
  11. Nicholas
    I read drink bouillon in water. The one I have has some carbs in it is that ok? Also would pickle juice be ok and not break the fast?
    Reply: #212
  12. Kristin Parker Team Diet Doctor

    I read drink bouillon in water. The one I have has some carbs in it is that ok? Also would pickle juice be ok and not break the fast?

    Boullion should not have carbs; you may want to check and make sure there's no sugar or starch in there. Dr Fung recommends coffee, tea or bone broth aside from water. I do not know if pickle juice would break a fast.

  13. Jno
    7 minute abs? How about 6 minute abs? Yeah that’s the ticket that’s the number.
  14. Purity
    I have started my fasting 2 days back... Now i dnt know which foods to eat and which ones to avoid.
    Reply: #215
  15. Kristin Parker Team Diet Doctor

    I have started my fasting 2 days back... Now i dnt know which foods to eat and which ones to avoid.

    You can see our keto recipes here to give you an idea of what to eat.

  16. Raishi
    I have dinner at 7 and my next meal is at 1 noon which lchf meal brrakfast is a cuo of coffee with little cream than i in between i have water and green tea it's my 3rd day
  17. Daniel
    I used the 16:8 diet to lose 5 kilos in no time, i eat whatever i want during the eating period and i'm still losing weight (yes even a burger and french fries once in a while).
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