8-Hour Diet: Fast 16 Hours to Lose

The 8 Hour Diet is a popular weight loss plan from David Zinczenko the author of the best-selling book Eat This Not That.

8 hour eating window

With this diet, David promises readers that they can lose 20-60 pounds or more and still eat whatever they want.

The key to the 8 Hour Diet is only consuming calories within an eight-hour window each day.

Zinczenko himself lost 7 pounds by eating according to this method.

His concept isn’t entirely new as there have been several diets over the years that promote intermittent fasting as a way to lose weight. Here’s how his version works.

8 Hour Diet Basics

This diet works on the theory that the human body is designed for periods of eating and then periods of fasting.

This involves consuming calories over an 8-hour period and then fasting for a 16-hour period each day. During the 16-hour period, the human body should be focused on repair and rest, rather than continually digesting food.

8 Hour Food Window

All of a dieter’s daily calories must be consumed only during his/her predetermined 8-hour eating window.

For example, if your calorie window is from 9 am to 5 pm, you must eat during that time period only.

The window can be adjusted depending on a person’s schedule and can be different during different days of the week. Dieters should eat this way at least 3 days a week at the beginning of the diet and gradually increase towards the ultimate goal of 7 days a week.

Eat Whatever You Want

8 hour diet explainedThere are no forbidden foods on The Eight Hour Diet, but Zinczenko does advise that this diet is not an excuse to overeat. Portion size must still be considered.

The only exception to this rule is sugary beverages since the 8 Hour Diet discourages drinking calories.

Delay Breakfast

Dieters should delay eating breakfast until the beginning of their food window. For example, If you can’t start eating until 10 am, Zinczenko recommends starting the day with a cup of tea, water, or coffee and doing some light exercise before any calories are consumed. (similar to 6 Weeks to OMG Diet)

Eat as Often as You Want

Snacks can be eaten as often as a dieter wants as long as all eating is within the 8 Hour Diet window.

Portion size should be considered when choosing snacks.

Supercharge the Diet

The 8 Hour Diet shows dieters how choosing 8 healthier power foods instead of processed and refined foods can dramatically increase the effectiveness of the diet and the dieter’s overall good health. The book gives suggestions on how to easily incorporate these foods into the diet.

Sample Meal Plan

Upon Rising

Water, coffee, or tea

Breakfast (10 am)

Oatmeal with blueberries and maple syrup
Coffee, tea, or water


1 granola bar


2 slices of pizza
1 8oz bag of potato chips
1 apple


1 fudge brownie

Dinner (5:30 pm)

Grilled Salmon Steak
Baked sweet potato w/butter
1 cup of broccoli
½ cup ice cream

Only 8 Minutes of Exercise

To be successful on the 8 Hour Diet just eight minutes of exercise is required to turbocharge the fat burning process.

Exercise suggestions for the most effective calorie burn are included in the book. 

The Cost of the Diet

The 8 Hour Diet: Watch the Pounds Disappear Without Watching What You Eat retails for $26.

Buy this book from Amazon.

Zinczenko Talks About His Diet

Why The 8 Hour Diet Works

  • It all comes down to calorie restriction. If you can find a way to keep the calories low enough to result in weight loss, you will be successful. By only having 8-hours to consume your food, you might be able to trick the body into taking in fewer calories.
  • This diet reminds me of a couple of years ago when Oprah talked about cutting off your eating at 6 pm as a way to lose weight. This became a popular diet trend for a while because it helped to prevent late night overeating and excess calorie consumption.
  • Intermittent fasting has shown health benefits.
  • Another benefit is that you don’t have to deprive yourself. Many of us have been through so many diets that we feel overwhelmingly deprived. This is bad for our long term success. We need to learn how to feel comfortable making choices that aren’t so healthy, but in exercising excellent moderation and portion control. 

The bottom line is: The body knows calories in and calories out for the entire day. So, if you can eat balanced, keep the metabolism going strong, feel healthy, then it doesn’t matter too much when you eat. It matters how much you eat.

Where This Diet Could Fail

  • The authors claim that the types of food don’t matter too much. However, you can’t expect to eat 1200 calories of chocolate for your diet and feel amazing. We must continue to eat a balanced portion of fruits, vegetables, lean proteins, healthy fats, and a few healthy carbohydrates. The authors do support healthy eating with the 8 Hour Diet Power Foods, but they don’t want to restrict you.
    8 hour diet power foods

    Eight Hour Diet Power Foods

  • It can be tough to stave off hunger in the evenings. For example, if you start eating at 8 am, then you can’t eat anything past 4 pm. What are you supposed to do if you feel hungry again at 8 pm, and don’t go to sleep until midnight?
  • Many suggest waiting to have breakfast to help with this. But, research proves that breakfast is best for the metabolism if eaten within the first hour of waking.
  • Not suitable for those with unstable blood sugar.
  • The authors say that you only have to follow the diet 3 days per week. This seems odd to me. Why not follow it 6 days per week? 3 days is only about 43% of the time. This doesn’t seem too effective.
  • This is not a new diet idea. Intermittent fasting has been around for quite a few years now but has yet to gain popularity until now.

In the end, the positives and negatives seem to balance out. I have a feeling it will work for about half of the people who try it.

So, try the diet if you like, and let us know how it goes for you!

 By Mizpah Matus B.Hlth.Sc(Hons)
  • Mattson, M. P., & Wan, R. (2005). Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems. The Journal of nutritional biochemistry, 16(3), 129-137.link
  • BLOOM, W. L., & AZAR, G. J. (1963). Similarities of Carbohydrate Deficiency and Fasting: I. Weight Loss, Electrolyte Excretion, and Fatigue. Archives of internal medicine, 112(3), 333-337. Link
  • Brownell, K. D., Greenwood, M. R. C., Stellar, E., & Shrager, E. E. (1986). The effects of repeated cycles of weight loss and regain in rats. Physiology & Behavior, 38(4), 459-464. link

263 Comments or Reviews

Comments now closed
  1. Cynthia

    I have been on the plan for 6 days and have lost 5lbs. We are very active and are eating clean. However not depriving ourselves with a small treat. Love it cant wait to see how well we do.

  2. Dot

    I want to know if you can drink water after your 8 hours of eating or is there no drinking anything till breakfast

    • Ed

      Yes you can drink as much water as you like after your 8 hrs

  3. Neil

    Im swimming 98 lengths front crawl in an hour in a 25 metre pool a day so hoping fasting will work. im on 12 noon-8pm window

  4. Claire

    I’m definitely going to start this tmr I do find if I don’t eat after 7 it does work, but it’s just being consistent, I have no will power, but I’m determined this time, wish me luck🙄🙄💪💪

  5. Debbie

    I have lost 7 pounds in 2 months following this plan. I also limit wheat products and root vegetables. It’s been easy to follow. No counting. No measuring. No hunger.

  6. Ed

    Well all I can say is I’ve done this before it is not a diet it is a life change within two weeks u usaly feel your energy going up your muscles starting to form without doing excercise so I would not bother if your not losing weight for the first few weeks your body is starting to heal itself build up your muscles which can be heavier than the fat your losing it’s not hard to follow eat what you want for 8hrs drink only water after the 8hrs and for those who say they are not losing weight this might be true but I bet they still feel a lot stronger and healthier than they ever have

  7. Hi

    Can you have sweetener in black tea and coffee? I need to lose 1.5 stone

  8. Jen

    Bullshit. 2 slices of pizza, potato chips, and brownie? Are you really doing your body any favors with that? Where are the nutrients in this “example meal plan”. Total crap.

    • Jolene

      It’s laughable really!

    • Ellie

      I know – I was shocked. It includes crisps, ice-cream, pizza and a brownie in an ordinary day. I’d think I’d had a treat if I just had one of these in a day.

  9. Alfonso

    Can I start the eight-hour window after 1 pm? Or should it be conducted prior to noon? My goal is 1 pm to 9 pm; is this sustainable?

    • Jx31@

      Yeah I start at 12 I usually break my fast with some fruits, apples, bananas, then for dinner some chicken either baked or grilled and rice, after about a week the weight just starts falling off

    • Mandy

      I sometimes don’t start my window until 2pm. Once you’ve been on the diet for a while (I’ve been doing it five years now) your stomach naturally shrinks and you get used to not eating in the mornings. I will sometimes “forget” to start, look at my watch and it’s 3pm! But it works for me. I also regularly shift my window but I rarely start before noon and I do stick to the eight-hour window 7 days a week.

  10. Dr. Berg

    The only thing you should have while fasting is a cup of tea or coffee, water and nutritional yeast. NY is very low in calories and loaded with B vitamins your system needs. 30 calories breaks a fast. NY only has 20 in one tbsp.

  11. maya

    Can one drink cofee with milk at the fasting hours?

  12. Bruce

    Can i eat dime jello no sugar between this hours

  13. Catrina Martin

    I am going to start this tonight wish me luck I need to lose about 70 pounds

    • Connie Ijames

      Let us know how it is going Catrina, best of luck to you

    • Jen

      Make sure you’re actually eat food that is good for you. You cannot eat whatever you want and expect to have a wonderful result. Read labels and cut the crap out of your diet.

      • Valerie

        Hi Jen have to agree with you, no point eating crap need to eat healthy nutritious food to get full benefit .

  14. Kev71

    I’m not sure why so many people have questions about when they can eat…. it’s relatively simple to understand:

    1. Only consume calories within an 8 hour window. This includes consuming any food or liquids with calories. If it is outside of the 8 hour window DO NOT consume calories.

    2. Eat a balanced diet.

    3. This will work better if you add some form of calorie burning activity.

  15. Judy

    I need to loose about 100 lbs !!!! Help !!!

    • Ryan

      Don’t think what you have to lose. Setup a written goal and attack it. Consistentcy is the key. Intermittent fasting works really well when stuck to. Good luck.

  16. john

    I have been on this lifestyle for the past four weeks. I eat only between 1pm and 7pm, I exercise for 15 minutes, morning and evening, mainly core training as my weight is around my middle, and I walk an average of 2.5km per day around work, between 7pm and 1pm I drink water or black tea. I dont restrict what I eat however I focus on fruit, veges, fresh meat & fish, herbs, spices, a little cheese, 2-4 slices bread per day, a little butter, plenty of nuts and dried fruit, no deliberate sugar, takeaways or manufactured food. For a treat, twice a week I enjoy a coffee and muffin to indulge my sweet tooth. In the first four weeks I have lost 10 kg. My blood pressure has dropped significantly, I feel better and I am sleeping longer. My goal is to lose a total of 20kg. I don’t experience moments of overwhelming hunger however I’m not fanatical either and if the urge to splurge becomes overwhelming I eat something, even if it is outside my eating window. Similarly if I am invited out to friends I eat what they eat, when they eat it.

    • Pamela

      I’m going to start this today. and I know that it works I’ve seen people that do do this as a lifestyle and they never have to fight with their weight. it’s only takes the first day the first jobs and you must want it more than you want for health

    • Greg

      Cut out the fruit and the bread and add in their place healthy fats like avacado’s and you will lose weight faster. Sugar and carbs spike insulin which tells your body to store fat.

    • Lafayette S.

      Hello John, How much did you weigh when you started the 16:8 hour eating plan? How much did you loose after the second month? Are you going to continue with the plan after achiving your goal weight? A collegue told me about the eating plan today. I’m going to try it for a week, and take it from there. Ultimately I need to drop oodles of pounds or lots of kilos. For now however a drop of 10 kilos over the coming six to eight weeks would be sufficient. I walk an average of seven km daily. I hope that’s enough exercise. Thanks.

  17. karen

    i have been doing this for over a month now and cant believe much weight ive lost without really trying , nearly a stone but it does help i walk around 4 miles a day four days a week for my job

  18. Cindy

    I read all these comments for answers and tips on the 18.8 life style. While the testimonials helped, the repetitive question… well let’s just say, Ted’s a Saint!!
    If you are interested in this diet, and you scroll down, most of your questions have been answered.
    Now that I have sounded off. I would like to add, think of it this way if you’re hungry on the 18, your pang can be ,,You’re losing weight !! Good luck to each of you that are just starting this new chapter, and clapping for the ones who have been on this awhile.

  19. maria

    I’ve tried this diet before and the weight just fell off. However, I am 48 years old now and just hit the peri menopause. I am on natural bio identical hormone creams and I am constantly hungry. I am also addicted to 100% chocolate bars. I’ve gained weight and would like to know how I can loose some weight by trying the fasting again. I’ve also tried the 16 hour fast recently and lost nothing!

    • Jay

      Don’t eat the chocolate, you’ve just hit menopause it’s time to start really taking care of your body if you want to live longer

      • Jen

        Should be taking care of your body way before menopause.

  20. Sam

    Can you drink tea that is mix of green tea and roasted rice in the 16 hour fasting?

  21. Sue

    I have been doing this diet for the last 3 years every day, but I haven’t yet lost any weight, sometimes I fast for 17 or 18 hours a day for some weeks , I still don’t lose any

    • Sandy

      So, why do you keep doing it?

      • Sam

        Yeah that doesn’t make any sense also you may need to go to a doctor if you don’t see a weight change it might be a health problem

        • Some Legend

          It might be the fact that you don’t have enough exercise? Maybe sign up for the gym or go jogging (not sure if this might be obliged to you but you could get a dog for company on your jogs if you don’t already have one) because somewhere on this page or another I read it claims that you have to exercise to get the real deal. (:

    • Kate

      Hey, one of the dietician recommended that few people follow intermittent fasting unknowingly and thus, their body becomes accustomed to such eating style. She recommended that we change this eating style completely for a week or two and consume clean foods (whole foods, fresh, mostly fruits and veggies) without fasting at all. This way you will throw your body a surprise and might lose weight. Once your body gets accustomed to this new routine, go back to IF and add daily exercise.
      Hope that helps 🙂

    • Jen

      Well what are you eating?
      If you’re actually eating healthy, wholesome, nutritious foods then you’d be losing weight. If you’re eating pizza, brownies, and potato chips even if you’re in a caloric deficit then yes you won’t see results.

  22. Lee

    If I follow and watch my calories, eat healthy, fast from 11pm-3pm, and eat from 3pm-11pm; would it still work if I had my coffee when I get up that I use sugar free cream in?

    • NS

      The idea is to not consume any calories outside of the 8 hour window. So you can have black coffee, but would have to cut the cream since the cream has some caloric value.

  23. JJ

    Can I eat vitamins beyond this 8 hours? Does this affect weight loss?

  24. Sally

    I’ve been on this diet for a week now all 7 days eating from 1-7 it works well but I still tend to eat too much.saying that,I’ve lost a bit of weight so I will carry on.

  25. Sue

    I have been eating like this for the last three years and I haven’t lost any weight, I am still doing because there might be other health benefits but definitely losing weight is not one of them

  26. Anne

    In the “Where this diet could fail” section of the article above Mizpah observes it seems odd that the 8 hour diet only has to be followed 3 days a week, but she had already pointed out that the diet should gradually be implemented by starting with 3 days and working towards 7 days. Interestingly my PT was talking to me about this diet recently and I commented I would have to gradually introduce it both in terms of days and also the number of eating hours per day.

  27. Robyn

    Just started today
    Wondering what happens if I eat under the recommendation of 1200 cal in the 8 hrs , will that slow down weight loss?

    • NS

      The fewer calories you take in the more weight you will lose. The minimum 1200 calorie recommendation is because if you are eating less than this, you are very likely depriving your body of essential nutrients that it needs to remain happy and healthy. Eat a healthy amount of food and exercise. An estimation of your daily calorie intake for weight maintenance can be found by multiplying your body weight in pounds by 15. If you eat 1000 calories less than this per day, without exercise, you will lose weight at a rate of approximately 2 lbs per week. It is not recommended to try and lose weight any faster than this, as that only makes it more likely you will gain the weight back when you stop dieting.

  28. Deb


    Just a quick question. I know they say that eating breakfast is the best way to kick start your metabolism (and it even says in the abve article as issue with the 18:8 is not having breakfast within the first hour of waking) so how does this work/impact/affect people?
    I get up at 6am and gym until 7:30am. I then go to work and usually eat my breakfast on arrival 9am. If I was to start the 16:8 I would use a 12-8pm window as I exercise again 5-7pm so need time for food afterwards.

    This means that after exercise Im not eating for a few hours and quite a few more after waking.
    Does anyone else have a similar routine and has it been efective?

  29. Chuck

    It’s called 16/8 Intermittent Fast..The above program isn’t it..It’s about reducing insulin levels..has nothing to do with calories..True you only eat during 8 hr window..but only water and black coffee no sweateners even sugar free..There is alot on this subject..I think the author just reconfigured the fast and calls it a diet..If your interested in doing this right and loose weight listen to Dr Fung on YouTube..then you will get this. Make sure your 16 hrs fast includes sleep time..You will be less hungry..I stop at around 5 30 pm then sleep and fast till 9 30 am next morning and Breakfast time..easy life style..not really a diet.

    • Sue

      Not everyone can wake up at 9.30. Some of us has to wake up at 6.30 or different time

      • NS

        He never stated he woke up at 9.30. He said he fasted till 9 30 am. All we can really assume is that he wakes up at some point in time between 5:30pm and 9:30am the next morning, including the possibilities of waking up at 6:30pm, 6:30am or 6:30pm and 6:30am.

        If you’re only going to comment negatively on various posts, please at least have the decency to try to sound mildly intelligent and literate.

      • karen

        Negative reading for others !

    • john

      I agree with this, i’ve never referred to it as a diet, its a lifestyle and when we cease using the term diet we cease trying to find ways to avoid dieting. I also use sleep time as part of my 16 hour window, as a result if go to bed earlier, sleep longer and that is 8-9 hours where I’m not even thinking about food. Then the morning slips away at work, before my 1pm – 7pm eating window opens. The biggest challenge can be weekends when work isn’t available to act as a distraction – so I have lots of hobbies and I keep busy Saturday and Sunday morning.

    • Nick

      Thanks chuck

  30. Eden dalton

    Do you think it will be better if i just eat healthier meals/snacks instead and can i do it 7 days a week instead of 3 so i can see faster results?

  31. Bijal

    I am following this pattern since over 1.5 months, eating strictly between 9-5. But I don’t see my self loosing weight at all.

    • NS

      It’s all about calories in vs calories out. Timing isn’t crucial as long as you’re consuming fewer calories than you burn.

  32. Len

    Can you take vitamins and supplements before starting breakfast?

  33. Ashvin

    Can a person consume water and vitamins outside the 8 hours of eating window? I am a vegetarian and consume fruit and Beggie smoothies but drink 4 glasses of water first thing in morning after waking up. Will that be an issue or alternative suggestion. I consume about 12 glasses of water on daily basis between 9 am to 9 pm

  34. Claire

    How many calories lost within 16 hours?

    • NS

      It depends how active you are during this time. If you’re sendentary and don’t consume any calories for 16 hours you would burn 2/3 of your Basal Metabolic Rate (BMR), which is the amount of calories your body burns at rest each day.

  35. Lashay Fairley

    Hello I been fasting for week and half lost 7lbs so far yeah I’ll keep posting

  36. Pauline

    Do you have success stories

  37. Henry

    I did this and in 6 weeks I lost 6 kilos, and my BMI staretd at 30 so I was not that overweight. I love food and have never succeeded at diets where you need to watch what types of food you eat. This diet fits so easily into my life – if I have dinner with friends I fast until lunch the next day. If I have breakfast with my kids and lunch at work then I skip dinner. Its really not that tough once you get into it, and is long term manageable. I also donated £5 to a homeless person every day of lent instead of buying the meal I missed that day. It felt great and motivating. I see no reason why you cant do this 7 days a week. Good luck people, I’m aiming to drop another 6 kilos in the coming weeks 🙂

    • Pauline

      That sounds so easy I have about 10 kilos to loose but just can’t seem to get into any diet at the moment hopefully this will be the one. Thanks

    • Sue

      I am doing it every single day for the last 3 years, I eat from 12 to 8 and fast the rest and I still haven’t lost any weight, I even fast for 18 hours sometimes and still not lose any weight

      • taniya

        You keep saying this but don’t explain why you are still on it then? what is the purpose of reposting the same comment?!

      • Nick

        Hello is it not what you eat Sue

  38. George

    Should the period of the fasting be consecuative ?

  39. Michelle

    Is it okay to exercise in the morning before your food window opens up on an empty stomach? I like to run or work out daily before work? medium to high intensity type workouts

  40. Emma

    I fast from 8pm until 12pm noon the next day, but exercise 6-7am every day fasted with no food until noon. Is this safe?

  41. Russell Shapiro

    I started 11 days ago. No sugar. Fasting from 8pm till 2pm. Lost 2.5cm around my waist in first week! No mood swings. No stress. Feeling great!

  42. Michelle

    I am new at this so any tips would help thanks

  43. Nikkole

    Hi I’m just reading about this never heard of it before just wondering so I stop eating at like 8 then don’t eat til 10 am !! Thanks

  44. Sarah-Eliza

    Hello. Does taking omeprasole/losec first thing in the morning (to put a lining on the stomach to protect the lining against anti- inflammatory damage) during the fasting period affect the success of the fasting? Thanks 🙂

  45. Doxa

    So what is the right amount of calories to eat and how many kilos are we expected to loose as a guideline in a week ?

  46. Fran Radomski

    So far this is working great. I started 2weeks ago and have lost 4pounds already with very limited exercise. For me this is a wonderful idea and I think I can keep it up as a life style.

  47. Deb

    Why would your blood sugar levels go up with this diet?

  48. Deb

    I’m a 63 year old female. I have been following the 8 hour diet for 8 days. I have lost 7 lbs. I had to have a blood test and my sugar went up 25 pts. Any idea why?

  49. Deb

    I have been following the 8 hour diet for 8 days. I am a 63 year old female. I have lost 7 lbs. But, had to have a blood test. Sugar went up 25 pts. Any ideas why?

    • Debbie

      If you have metabolic syndrome or diabetes you still have to count your carbs.

  50. Harika

    Hi Ted
    I want to make sure 8 hours eating time , for example can I eat cookie , cake ,ice cream what I want 🙂

Last Reviewed: January 25, 2018