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

Snack

1 granola bar

Lunch

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

Snack

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.

17 Comments

  1. Rae

    During your 16 hour fast, can you drink water?

    Reply
    • Ted

      yes, you absolutely should.

      Reply
    • 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.

      Reply
  2. 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!

    Reply
  3. Danielle Felty

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

    Reply
    • Ted

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

      Reply
  4. 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!

    Reply
  5. Jack

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

    Reply
    • Ted

      Yes, you can eat fruit during your window.

      Reply
  6. 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

    Reply
    • Ted

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

      Reply
  7. 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!

    Reply
  8. 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.

    Reply
    • Michelle

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

      Reply
  9. 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.

    Reply
    • 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 🙂

      Reply
      • 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.

        Reply

References

  • 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