8-Hour Diet: Fast 16 Hours to Lose

By Nicole German (RD, LD)

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.

Click here to purchase this book for a discounted price (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!

The 8 Hour Diet can be purchased for a discount here as a hardcover book or as a Kindle book.


  1. Sam

    Can women follow “The 8 Hour Diet” book or is it for only men? And can you drink water anytime?

    • Ted

      It’s is for both genders and yes, you can have water anytime.

  2. Michael

    Can you drink bovril during the 16 hour fasting period?

    • Ted

      I’m not sure what that is, but you can drink any beverage that is zero calorie.

      • Michael Doherty

        It’s a beef flavoured drink.

  3. Jake F

    Hi I’m 19 year old and am in college I’m just wondering if you can adjust your window during the week , and also I’m 270 lbs I wanna lose atound 20-30 lbs what calorie intake woul you suggest to make this happen I also workout for 2 hours a day.

  4. Tina G.

    I lost 35 lbs over a 4 month period

  5. G Baker

    What about if you have to take medication twice a day that states must be taken after food?
    I have Chronic Rheumatoid arthritis and have to take Dicofenic sodium tablets and steroids both of which must not be taken on an empty stomach, risk of bleeding:
    Taking these tablets over an 8 hour day rather than the twice daily 12 hour I currently do would leave me in more pain and morning stiffness if I have to delay my breakfast to lunchtime.
    I could do my 8 hours earlier say from 7 to 3pm, but then I get the same problem at the end of the day instead?

    • Ted

      It doesn’t seem like the 8-hour diet would be a good fit, since you have medication issues. Check into Flexible Dieting instead.

  6. Noelie

    I measured my self last week around the middle and i put on a inch i have been on the 8 hour window diet for a month now last 4 inchs around the middle eating less only eat fish chicken brown rice all good foods and i walk 8 miles a day and i put on a inch dos any one know why u do this

  7. Hayley

    I’ve recently started the 16:8 diet.. well been on it a week now.. I exercise alot & on my feet at work all day.. I also eat between 1pm & 8pm is this to late.? But no later than 9pm..!!! I drink alot of tea with sweetner & milk is this okay on the diet.?

    • Ted

      It’s my understanding that whichever 8-hour window that works for you is fine. Also, tea with sweetener would be fine outside your window but tea with milk would not be allowed.

      • Hayley

        Ahh I see.. well that will now change.. is fruit tea allowed.? Thank you.

        • Ted

          Any zero calorie beverage is allowed during your fasting window

      • Sarah

        I don’t think a sweetener should EVER be allowed. They are terrible for you. Try honey instead.

        • Ted

          Stevia is horrible for you? Even with the artificial sweeteners, there is little data to support that notion.

      • Cecelia

        Can we take lemonade during 16 hour fasting period without sugar

        • Ted

          yes, lemon water is fine.

  8. Noelie

    Ok thanks ted no more tea for me then only had a tea this morning so wate any more

  9. Noelie

    Can u have tea with milk and sugar when i get up in the morning?

    • Ted

      If it has milk and sugar it has to fall within your 8 hour window.

  10. Liz greene

    This diet is the best I have ever tried. I lost 6lbs in the first week
    I dont feel hungry
    I easily stop eating at 7pm
    Drink and am still losing weight
    i exercise a lot in morning burns calories love this regime so easy cos i an eat cheese loads of veg and feel great

  11. Tiffany

    Apparently i have been doing this for years.
    I work swing shift 7 days a week i only eat at work and I work 8 hour days.
    My body must be used to this because it doesnt work for me.

    • Mike

      I thought the same thing when I started this diet a fortnight ago. Turns out I’d been only eating in more or less an 8 hour window for years, true enough, but was starting the day with several sugary milky cups of tea in the early morning (and occasionally during the night), and also drinking a few beers every evening, stretching the hours I was taking calories in to between 7am and 10pm every day. Once I restricted my *entire* calorie intake to within an 8 hour period (whilst still eating and drinking more or less the same stuff), seven days a week, I saw rapid results and have shed 10lb , without any massive increase in exercise. No idea if the weight will stay off, I guess time will tell.

  12. Victoria

    During the 16 hour fast can I drink tea or coffee with milk?

    • Ted

      You could have black coffee or plain tea. Sugar and milk would add calories which would break the fast.

  13. Morgan

    Is it OK to drink wine or beer to the dinner?

    • Ted

      Yes, as long as it’s in your 8 hour window.

  14. Janet

    Do you have to stick to the same 8 hour window of time every day or can you change it regularly? Thanks!

    • Ted

      It’s fine to change, but you always want to have a 16-hour fasting window in between eating.

  15. Elsa Kleynhans

    I have been on the 16:8 diet for four months and I do not loose weight. As a matter of fact I am gaining slowly.
    I am Female 69 years of age no exercise except for 10 000 steps per day.
    Somebody said I now messed up my metabolism following this diet because of my age that is why I do not loose weight. My sugar levels are 5.6.
    Not once in the four months did I cheat to eat in the 16 hours time frame.
    At 10 o’clock I eat 70g of wheat free breakfast cereal and 70g yogurt. Most of the times I then don’t eat until 4 o’clock I then eat a meal with something sweet but sugar free and wheat free. The last couple of weeks I added soup over lunch time to try to speed up my metabolism.
    I do not drink alcohol or eat red meat only fish and chicken.
    I eat a lot of cheese think to much.
    I eat no starch but do eat gluten free pasta once in two weeks.
    I eat no bread what so ever except gluten free pizza once in two weeks.
    I see no reason why I am overweight with the amount of food I consume. All treats are made by myself with almond flour and Xilatol or Truvia sweeteners.
    I am 1.56 cm in height and I weigh more than 54kg that is to much I want to weigh 50kg.
    Could you please give my some advise.

    • Ted

      Hi Elsa, It’s also about making sure you are eating the right amount of calories. Too few calories can even slow your metabolism. read here: https://healthyeater.com/eat-to-lose-weight

    • Elsa Kleynhans

      Thank you Ted. I am going to ask my son to bring me the book from America, I live in South Africa.
      I saw the sample diet and I am going to try that, a lot of food I must say for one day. It is unthinkable to eat a slice of pizza and a bag of potato chips. I forgot what a potato chip tastes like. Let alone the heavenly taste of a chocolate brownie.
      Please can I find a week of sample meals until I can get the book.
      Thank you. Elsa

    • a

      Try cutting out all dairy and nuts…give it 30 days and see if it drops then…

  16. Rae

    During your 16 hour fast, can you drink water?

    • Ted

      yes, you absolutely should.

    • Joe

      Yes. You can drink water. You can also drink non calorie drinks, like coffee and tea. I’ve been back on this diet since May of this year. And I’ve already lost 30 lbs. I get up at 6:30am and have four cups of coffee. My first meal is around 1:30-2:00pm. Then supper around 6pm. And if I’m still hungry, a snack around 8pm or so. I also do bodyweight exercises six mornings a week. I’ve never felt better. I highly recommend this way of eating. I went on it the first time one year ago and lost 20 lbs. Then as soon as I went off of it, gained the weight back in no time. Sticking to for good this time around.

  17. Leandro Santos

    Congratulations for your nice job in your book. I’m from Brazil and I have some doubts. What’s the diference between intermittent fasting and 8 hours diet? I think it’s more simple to undertand 8 hours then 16 hours of fasting, and I know I’ts basicly the same, but the problem is when you do this 3 days a week. It’s correct eat 8am to 8pm in a normal day and after do the 16 hours of fasting? When you do daily it’s more clearly that we only eat 8 hours and for consequence you always will do the 16 hours of interval, but whey you do this 3 days a week i’ts not so clear. If I eat 11am to 7pm and the next day I don’t do the diet I’ts necessary that I will eat only 11 am? Many Thanks!

  18. Danielle Felty

    can you have low sugar protein drinks in the fasting period?

    • Ted

      No, If you are eating protein, you are not fasting.

      • Laura

        So after a workout you can’t have a protein shake? Or can you if it falls into your eating window ??

        • Ted

          You can as long as it’s in your 8-hour window.

  19. Amber

    About 6 years ago I was 26 years and I weight 300 pounds. I hated life, I couldn’t do most things comfortably.
    I made a choice not to undergo weight loss surgery, I wanted to give my will power a chance. I did something similar to this and I went from 300 pounds to 150 pounds in 9 months! Yes I did! I went from a size 28 in plus size women’s to 6/8s in misses. I have kept most of the weight of in the last 6 years. I have put on a few pounds but I have made plans to going back to this way of eating.
    I work evenings so I eat about 2pm and I eat a good meal and then I eat I might have a light snack , but nothing else until 2 pm the next day! The key I think is a lot of protein and light cards. I hope my story helps!

    • Dee

      I like your story Amber. That took a lot of will power! Working evenings plays havoc with one’s body, so I admire how you got to slim down. Keep up the good work!

    • G

      Amber what an amazing story, well done! 😊

  20. Jack

    Hello, during the 8hrs can u eat, watermelon, spples and like fruits or no

    • Ted

      Yes, you can eat fruit during your window.

  21. Ann ferris

    Well l have been doing two weeks 8hour diet I start about 12. To 8 my skin feels lovely but not shifting any weight my tummy feels flat I do excise so l don’t know why can’t shift the weight can you help

    • Ted

      What do you mean when you say “shift the weight” Where are you wishing to move it to?

      • Dee

        Haha, sharp wit!

  22. Joan

    This diet works and is useful in maintaning your ideal weight once you’ve reached your goal. Easily lost the 65 lbs I gained while pregnant within in the first year of having baby 3 with out stepping foot in the gym!

  23. Constance

    This diet does work well for fat people. You can’t figure out how to get fat people to lose weight by studying thin people or lab rats. Anyone who is headed towards metabolic syndrome or type 2 diabetes (where people have high insulin levels and high glucose levels) will likely benefit from this diet as it keeps your insulin and related metabolism hormones stable most of the day. As soon as I eat I start getting hungry and I never get full. Now I don’t eat until noon, I am much less hungry and I eat a whole wheat piece of toast with peanut butter at 8pm which holds me over until noon the next day. I park my car a mile from work and walk in as fast as I can. I lose at least a pound a week and have lost as much as 3 pounds in a week and I am far less hungry.

    • Michelle

      So you start eating at 8:00am ? Am i right?

      • Candy

        You can start at anytime that suits you and finish when suits you as long as the window from start to finish is 8 hrs. Eg 8am -4pm, 10am-6pm, 12pm-8pm or 2pm-10pm. Tailor it to suit you

  24. Spectra

    I do intermittent fasting as my normal way of eating. I’ve heard it called eating “warrior style” a few times–I eat most of my calories within a 4-6 hour window and then fast until the next window. I don’t ever feel hungry in between, probably because I eat mostly a plant-based diet that keeps my blood sugar very stable. I suppose you’d run into more problems if you ate 1200 calories’ worth of processed garbage, but I don’t, so it works for me. It really does help you stick to your calorie intake for the day because you get pretty full during the period you’re eating and don’t want to overeat. I don’t know, maybe our bodies are actually designed to eat that way–after all, it could have been almost a whole day in between kills/meals when our ancestors were hunting and gathering.

    • marita tirado

      Hi Spectra , can i ask you a question ? If i fast for 4 or 6 hours ….. it has to be 1,200 calories . ? THANK YOU 🙂

      • Catherine Swann

        OK, here I am, former PE teacher and ex-very competitive long
        distance athlete. I was great until I turned 62, then I gave up,
        and now am 50 lbs. over weight , completely out of shape. I’m
        a little concerned about this diet, although it sounds logical…
        a lot better for me than ATKINS which I absolutely can’t do; makes me sick. On a general guess, what amount of people
        cheat on this eating program and fail to lose. I’ve been doing
        diets since I was 12 yrs old, so just as long as I’m not thrown
        into ketosis (Atkins) I should do well. Just went to my doc,
        who says I’m generally in good shape. Thanks.

        • Linda Sandoval

          I’m losing more inches then seeing the scale move. However, I am overeating during my 8 hour window. I am an emotinal eater, I hear that you can still lose just at a slower pace, are there any People that you know have lost weight overeating but just losing at a slower rate? Please advise and thank you in advance



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