How to Eat: Fast and Break-Fast

//How to Eat: Fast and Break-Fast

Several interesting recent studies regarding meal timing that deserve some attention. The first study, part of the Adventist Health Study 2, looked at a large cohort of relatively healthy people. Adults (>30 years old) attending Seventh-Day Adventist Church completed health questionnaires every 2 years. Over 50,000 people participated, and this particular study looked at meal timing and its relationship to body weight.

There is a very widely held opinion that eating more frequently will help reduce weight over time. However, there is virtually no data to support this assumption, and it has gained reputability only through mindless repetition. At first glance, it sounds pretty stupid.

You should eat constantly to lose weight? How does that work? That’s like saying you should spray your clothes with water more often so that it dries faster. Eating more often generally results in more overall food intake. And increased food intake is not highly likely to make you lose weight. Nevertheless, frequent repetition by authority figures can convince us of anything.

So this study looked closer look at this relationship. Not surprisingly, the more frequently you ate, the heavier you are likely to be. Doesn’t really seem like rocket science. If you constantly eat meals and snacks, you will gain more weight. No sh**, Sherlock. The advice to eat constantly to lose weight sounds really stupid, because it is really stupid.

The study also noted that the longer you fast (18-24 hours) the more less you weigh. Again, not really hard to understand. If you give your body a good amount of time to digest your food and burn stored food (body fat) then you will likely weight less. This jives perfectly with much of the data on intermittent fasting and restricted eating windows.

But there is more interesting data here. Eating breakfast is considered a very important part of weight loss. Are they correct? Indeed, yes.

If you eat breakfast, you are more likely to weigh less. At first glance, it seems hard to reconcile the data. You want to eat less, have a long nightly fasting period, but still eat breakfast? How does that work?

Well, the answer lies in the circadian rhythm, which I’ve written about previously. Recall that insulin, not total calories is the main driver of obesity, although there is an overlap, to be sure. Different foods elicit different insulin responses, and therefore have different propensities to cause obesity. That is, 100 calories of cookies are more fattening than 100 calories of broccoli, despite what all the mindless calorie zombies tell you.

The same food will also elicit different insulin responses at different times of the day. Eating the same food at dinner (compared to breakfast) gives you almost 30% more insulin effect. In other words, food is more fattening when you eat it later at night. But the bad news for late eaters does not stop there. If you look at the circadian rhythm for hunger, you’ll find that hunger is lowest in the morning and greatest in the evening 8:00 pm or so.

Another study (Bo, S et al) found the same phenomenon. In this crossover study, they took 20 healthy people, gave them the same meal but either in the morning or evening. So both arms had exactly the same people, eating the exact same meal, but only differing by time of day. The evening meal stimulated significantly higher blood glucose and blood insulin response and insulin is the main driver of obesity. Even more interesting, the evening meal produced a much lower resting energy expenditure afterwards compared to the morning meal.

So, if you eat your largest meal in the evening, you suffer from 3 problems. You’ll be more likely to eat more (because you are more hungry – yikes), you’ll get more fattening effect for the food that you do eat (higher insulin – double yikes), and you’ll have lower energy expenditure (more calories will get turned to fat). TRIPLE YIKES!

So, to be clear. If you eat one meal a day, best make it breakfast. If you eat two meals a day, best make it breakfast and lunch. BUT eating 3 meals (breakfast/lunch/dinner) is not necessarily better than 2 (lunch/ dinner), which is often the message given out by the ‘Never skip breakfast’ mafioso. The best solution is to eat a large breakfast/ lunch and eat very little or no dinner. This gives you the benefits of both fewer meals and longer night time fast.

So why do I skip breakfast myself?

Because that schedule of eating does not fit my lifestyle. I tend to eat dinner with my family every night, and we rarely eat breakfast together as a family, because we’re rushing to school and work. So I skip breakfast, because it fits my lifestyle, and eat dinner. This is not optimal, but it is what works for me. I still get the fewer meals, and the longer night time fast, but I get the disadvantage of high insulin effect at night. However, it is precisely this knowledge of science and practical experience that allows us at the Intensive Dietary Management program to devise individualized schedules for people. Trying to shoehorn an eating schedule into an incompatible life schedule is weight loss suicide.

The other recent study that was fascinating was the MATADOR study. In this randomized study, patients either received energy restriction either as a constant 8 week block, or in 2 week chunks alternating with 2 week blocks of no energy restriction (eventually totalling 8 weeks of energy restriction).

So both groups got identical calorie restriction and standardized diets, but one of them (Control) got 8 weeks straight of ‘dieting’ then 8 weeks of ‘no diet’. The other group (Intermittent) got 2 weeks of ‘dieting’ followed by 2 weeks of ‘non dieting’ for a total of 8 diet weeks.

Does the ‘intermittency’ of the diet make a difference? You bet the hell it did. Not only was far greater weight loss after 16 weeks, but at 6 months, the difference in weight was 8.1kg – 17.8 pounds! Jay-sus. There was weight regain in both groups at 1 year, but things looked a lot better in the intermittent diet.

What explains this huge difference? The answer is the change in resting energy expenditure (REE) also known as basal metabolic rate. The REE is how much energy is burnt by the body at rest (not at exercise). This is the energy (calories) used up in generating body heat, keeping the brain, lungs, liver, kidney, heart etc. working properly. This is not a static number but changes up to 30-40% depending upon the hormones. As you lose weight, the REE goes down (less body mass to heat, less energy needed) so you need to adjust the REE for Fat Free Mass (FFM) and Fat Mass (FM). Decreased REE is the main reason for the failure of The Biggest Loser contestants. 

Constant energy restriction steadily decreases REE. This is why the constant calorie restriction as the primary method of weight loss is a consistent loser. If you cut, say 500 calories from your diet every day, as many health authorities recommend, your body will simply adjust by burning less. This Caloric Restriction as Primary (CRaP) method is doomed to fail. As you eat less, you burn less. Eventually you plateau and then you start the weight regain. Tears follow the silent accusations of your doctor that you just didn’t have enough will power. But the fault was not your. It was physiology. It happens to everybody.

Instead, if you ‘diet’ intermittently, the body does not adjust and REE stays significantly higher. You have more energy, you don’t feel so cold, and weight stays off. It is the INTERMITTENCY of the diet that makes it successful. We talk constantly about the question of ‘What to Eat’ but almost never consider the equally important question of ‘When to Eat’. That is the reason, in my Intensive Dietary Management Program, we stress that you sometimes need to change things up.

One common question is whether eating one meal a day is acceptable. That is a daily 23 hour fast. Sounds pretty good. And it works well for a lot of people. But a lot of people will also plateau at a weight higher than they would like. At that point, we suggest that they do something to change the schedule. Sometimes we’ll suggest changing the diet, and other times we’ll suggest changing the fasting regimen. If you have plateaued, just do something different.

Lastly, I’d like to say a few derogatory words about the recent study about skipping breakfast and getting heart disease   – based on 4000 adults in Spain, breakfast skipping was associated with more heart disease. The media is having a field day proclaiming that skipping breakfast causes heart disease. Oh, My, God. You must always eat breakfast, even if it is a Krispy Kreme donut! Oh, My, God. I can’t believe you have been awake for almost 2 minutes and haven’t started cramming food into your mouth. Call 911! Oh, My, God. You need to sleep in the kitchen so you can shovel food into your mouth before your feet hit the floor. By the way – why can’t you lose weight?

Even the author is not so stupid as to suggest a causal relationship. He said ‘It’s not that you skip breakfast, you get plaques’. Of course not. People who skipped breakfast were also at higher risk of heart disease for other reasons, too. It’s kind of like saying that people with grey hair are at higher risk of dying (true – because they tend to be older). Therefore, to reduce the risk of dying, you simply need to dye your grey hair black. There’s a clear association with having an ‘A’ on top of your test and doing well in school. So, obviously, to do well in school, you should write ‘A’ on top of every test your write so you’ll do well. It’s absurd. But that doesn’t stop the media hype.

Understanding the science helps cut through the bull. There’s nothing wrong with eating breakfast. Eating more at breakfast and less at dinner makes physiologic sense for weight loss, because it reduces the insulin effect. But if you eat the same dinner but add breakfast, don’t expect that eating more food makes you lose weight.

2017-10-04T14:49:53+00:00 60 Comments

About the Author:

Dr. Fung is a Toronto based kidney specialist, having graduated from the University of Toronto and finishing his medical specialty at the University of California, Los Angeles in 2001. He is the author of the bestsellers ‘The Obesity Code’ and ‘The Complete Guide to Fasting’. He has pioneered the use of therapeutic fasting for weight loss and type 2 diabetes reversal in his IDM clinic.

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60 Comments on "How to Eat: Fast and Break-Fast"

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John C
Guest
This post is well timed for me. I had recently shifted my eating pattern to mostly eating only one meal a day in the evening. This was easy on LCHF because I didn’t get hungry during the day, but my weight started to creep up, probably due to the effect explained in this post. I had already started adding lunch on some days and eating less in the evenings which halted the weight gain and I will now eat breakfast some days and skip or reduce dinner and/or lunch. I constantly vary the size and timings of my LCHF meals… Read more »
John Brown
Guest

Love the post. However, this one has a lot more expletives compared to others. It undercuts the feel of authority that I’ve come to appreciate and is distracting. You can get the point across without using that. Please consider that one of the reasons why The Obesity Code is so compelling is the straight-forward approach. No chicken little alarmism. No fad diet hype.

TeeDee
Guest
I’m always interested in seeing new studies, but regardless of what they say, I’ve found what works best for me and it’s not eating breakfast. I feel like I’ve been pulled in every direction on things like meal timing, eggs being bad, then good, coffee being bad, then good, then bad again and on and on. I’m glad for it in a way because it forced me to do my own experiments with meal timing and food choices and now I can more clearly see what’s best for my health goals. I eat my main meal around noon and then… Read more »
Tamarah
Guest

Same for me,, I cannot sleep on an empty stomach,, I toss and turn all night . I am OMAD and its at dinner,, I am watching my weight it fluctuates normally as usual,, if I see it going off the rails,, at that time I may have to reevaluate ,, but for now I am good .

Tiffany
Guest

I love this so much! As a lifelong “dieter” I cannot get enough of the science behind weight loss, and I really appreciate the way Dr. Fung presents the data. It is enlightening to finally understand why my former approach (CRaP) never produced lasting results and why I always ultimately, eventually, fell off the wagon. I have lost about 25 lbs doing keto but have only dabbled here and there with IF. This article and the pilot episode of The Obesity Code Podcast have convinced me to do some more n=1 experimentation on myself with IF and longer fasts.

Ron Hunter
Guest

We need more doctors who will say things like “no shit, Sherlock” and drop an occasional F-bomb. Someone needs to start talking the straight shit. Keep it up Dr. Fung.

Kyle
Guest

This post is a bit confusing when compared to information given in THE OBESITY CODE where skipping breakfast seemed desirable for weight loss. ??

Sarina
Guest

I love the way you write Dr Fung. This information is priceless.

Christopher Simmons
Guest
I have been following the One-Meal-a-Day regime for several months now. I started with LCHF / Keto but I found all the heavy fat / coconut oil in coffee upset my stomach (usually have a ‘cast-iron’ stomach but keto made it really jittery). After reading Jason’s material I decided to try Intermittent Fasting. I went without breakfast (‘religious’ breakfast eater all my life), then missed lunch (not hungry) got hungry at dinnertime (probably because I cook most of our meals), then fasted overnight – it was so easy to just repeat this every day I just kept doing it. I… Read more »
Bucio
Guest
Dr. Fung, If I recall correctly you had another post identifying that drinking a cocktail of apple cider vinegar with water 30 minutes before a big meal or any meal would cause a reduction of insulin being released up to 30%. Do you think that would help with the other two issues as well or just the reduction of insulin? The reason I ask is that I also am a dinner eater for the same reason as yourself. I have plateaued a 166-170 and was also curious that if doing the apple cider vinegar before my dinner would help me… Read more »
Sheila
Guest

Crazy! I keep a jug of it in my shower to rinse my hair but I’ve never been able to tolerate the taste enough to drink it! The other day I was rinsing my hair and some went in my mouth and I thought, “That’s not so bad? I should drink some! It’s supposed to be so good for you and help you lose weight!” I didn’t know about the insulin!

Stephen T
Guest

Isn’t not eating breakfast the easiest way to add hours to the overnight fast? I try to give my body a reasonable break from eating every day, although that may be only 14 – 16 hours. A lot shorter than some, but way longer than most of the population. The important thing for me is that it’s sustainable.

Liana
Guest
Yep, my ‘problem’ too. I’m never hungry in the morning. Never have been even when young and in school. I would get physically ill (puke) if I ate before several hours had elapsed from waking up. I work nights from 9 pm to 5 am and go to bed at 5:30 am and sleep until 1 pm. My first meal is at about 4 pm (small protein mainly), dinner with my husband is at 6 or 7 pm (regular full meal mainly protein, fat, and low carb) and a midnight snack of protein and a bit of fat while at… Read more »
Stephen T
Guest

Liana, I’ve worked night shifts and my approach was not to eat for a few hours before going to bed. I think your eating pattern makes complete sense.

Tan
Guest

How is your weight loss/blood sugars numbers going (if that is a goal)?

Steve Stephenson
Guest

Any 7th day Adventist study is suspect per Dr Gary Fettke’s research: see https://youtu.be/DWCQF-FFJYk/ And collecting data via questionnaires is highly unreliable.

Roger Bird
Guest

In order to establish peace, we need to bomb relentlessly.

CSue
Guest
There are a number of typos that could be cleaned up in this article that will give it more credibility. However, I am grateful to Dr Fung. I did 1-2 meals a day IF for several years and my metabolism definitely slowed. No matter how little I ate I couldn’t lose weight. After reading his book I started fasting, and then I lost the weight. Now I don’t have to constantly worry about every morsel I put in my mouth, I know if I can a few pounds on vacation or whatever, I can easily take it back off by… Read more »
Gus Karageorgos
Guest

I’m not convinced that cycling is useful if one is on a ketogenic diet. Note, in that study carbohydrates as % of total calories was > 50%!

“The planned macronutrient distribution in both ER and energy balance diets was 25–30% of energy as fat, 15–20% as protein and
50–60% as carbohydrate.”

And it’s known that a low-calorie non-ketogenic diet will lower resting metabolic rate eventually (more than that predicted from the lowering of body weight alone). Thus, on a such a higher carb diet, cycling may be useful. But on a ketogenic diet, I think the jury is still out.

corrie
Guest

I hope Dr Fung makes a reply to the points raised in your comment !

Tan
Guest

I do too!

michael king
Guest

Calories are not restricted if you are a walking run of lard as most are if you are in ketosis. Eating 70 percent of calories fat it is easy to go 20-40 hours between meals. And in ketosis the body just nibbled on the lard hanging off your internal organs anyway.

Cheryl
Guest

I have a question for Dr. Fung. Intuitively, is the 2 week interval for intermittent dieting better than a 1 week interval and when you say dieting and not dieting, are you saying keto diet as dieting and non-keto as not dieting?

Lois Pearson
Guest

This is informative AND your writing is amusing.

Ray G
Guest

perfect timing. my lose has plateaued with one meal a day in the evening and I questioned whether a morning meal would be better. I easily have 40lbs to my goal

Sonya
Guest

Would having your one meal at say 3:00 be of any benefit or is it too late in the day? I’d like to get in my exercise while fasting and then cook my meal (I only do one meal per day usually). Plus, the meal could probably be kept reasonably warm for the rest of my family when they got home.

Stephen T
Guest

Sonya, I eat my second and final meal of the day at about 5.00 – 6.00 p.m. There are no hardset rules for me, except avoiding junk. So, if 3.00 p.m. works for you, then it’s fine and Dr Fung clearly eats later than that. We don’t need to be perfect to be good.

Sonya
Guest

Thank you Stephen! Love the phrase “we don’t need to be perfect to be good “👍

Ashley
Guest

How does working night shift effect insulin levels? Would it be better to eat your one meal after work in the morning before going to bed or at night when you wake up for work?

Wow
Guest

This man is a genius – I needed this information!

corrie
Guest

I hope Dr Fung and/or his staff read the comments section here… I would like to alert them that the older blog posts that have been transferred over to this newer platform have not fully loaded. The blog posts regarding calories, aetiology of obesity etc. all have error messages where infographics should be. I often pass on the links to interested people, but now cannot. How can anyone read the posts and be convinced of the information if the supporting infographics are not there?

Lisa Rogowski
Guest

Excellent article and I love the writing style. This came at the perfect time for me regarding breakfast or no breakfast. I am choosing a high fat breakfast and no dinner. That is what works for me. Thank you for this article!!

Jessica
Guest

Thank you for being so informative AND funny. I mean, really, how many people read health articles and laugh???

Northus
Guest
“If you cut, say 500 calories from your diet every day, as many health authorities recommend, your body will simply adjust by burning less.” I get why that would be the case if you cut the calories but otherwise ate “normally” (eg high carb and many meals per day, ensuring high insulin), but is it really true if you combine it with IF? In the first case the high insulin will prevent weight loss and so the deficiency in calorie intake has to be compensated somehow, so the body burns less, which is bad. But in the second case you… Read more »
Carl Juneau, PhD
Guest

Great post! Loved the MATADOR study. Reminds of intermittent fasting. It’s like intermittent dieting. Love it.

Keep up the good work!

Roger
Guest

I always find your information logical, scientifically sound and easy to follow. Accordingly, I refer many of my patients to your information.

Forest Simmons
Guest
Just because eating more in the morning and less at night tends to reduce body weight does not necessarily mean it is better. For our ancestors, more stored fat was a good thing, because (1) they needed that stored energy, and (2) it did not give rise to insulin resistance, since they were burning that stored fat. Similarly, I like to store my calories at night when it will be stored as fat so that I will have lots of fat to burn during the day. I would rather be a fat burner than a sugar burner because fat burns… Read more »
Sveinung
Guest

Great stuff as always. I also tend to skip breakf(e)ast – just because it fits my schedule – and I like to cook dinner. But might use this as a tool in the future if I want to push through.

Alan S
Guest

Can someone please clarify if for example the following situation:
If I eat LCHF (and positively in ketosis) and eating OMAD should I eat all the daily calorific needs in that one meal (without restriction) to minimise the insulin response from my food?

If so, that’s a hell of a lot of calories to eat in one meal. I would have thought if I’m already in ketosis then any calorific restriction my body needs would be supplemented from my body fat?

Stephen T
Guest
Alan, one meal might work for some people, but not for me. An insulin response is natural and not the enemy. The problem is the level of insulin generated by sugar and refined carb junk and the length of the insulin response caused by endless eating. I usually eat withing an eight-hour time window (11×7). I have no idea if I’m in ketosis, but I think I probably am at least some of the time. I’m not overweight and one of the benefits of LCHF for me is having control of my appetite, whilst still enjoying food. I don’t think… Read more »
Alan S
Guest
Thanks Stephen. I agree ive seen people eat LCHF with all kind of processed garbage. Im usually about 80% clean keto. Ive been IF fasting too but ultimately that means im always in a deficit so I was under the impression the extra calories my body needs would come from my body fat (but only if im in keto). I really only have 10Ilbs to lose now but its the last few pounds that are not shifting that easily. When I read this article that calorie deficit doesn’t help and the mention of hormones it always creates doubt in my… Read more »
Stephen T
Guest
Alan, I wouldn’t eat more calories unless you feel hungry or lacking in some way. Yes, if your insulin has dropped, you can burn fat, but you also need the vitamins and nutrients that come from food. When I started LCHF I lost a few pounds and then seemed to hit my set point, or natural weight. My weight barely moves now unless I eat or drink differently. 10 Ilbs is very close, so I’d be cautious of major changes. If other contributors can’t help you and you still want more, perhaps a spell in the IDM or Diet Doctor… Read more »
Claire
Guest

Another issue is that blood glucose can be artificially raised in the morning as a result of cortisol produced before getting up – dawn phenomenon. A small breakfast can lead to a shot of insulin which will deal with breakfast and that produced whilst sleeping.

Martin
Guest
This touched home with me — I can’t not take the meds at this time as I have proteinuria — despite denial, my A1c was still at 7.1. If I don’t, I’m risking advancing kidney disease. I tried intermittent fasting. I tried just supplements, but I wasn’t giving myself a chance with dedication to either. With the proteinuria, ketongenic is probably not the best approach. (I love food, am a foodie, but not really a carb eater — but I like meats and…. booze) I would rather pack my eating late (and take med in the evening to push my… Read more »
Martin
Guest
I recently learned my A1c was still at 7.1. I haven’t been dedicated, but I tried intermittent fasting. I also learned I have proteinuria. I tried supplement only (Chromium, ALA, etc) Original testing said I was merely glucose intolerant. I can’t not take the med at this point for risk of further kidney damage. I prefer eating in the evening so skipping breakfast is not an issue, nor is skipping lunch. As far as insulin spikes in evening, I decided I will take my med in evening (Januvia) to help push my insulin inward instead of back to my liver… Read more »
Martin
Guest

Addn: doc says if I lost 50 pounds (specifically 50 pounds — I’m 5.11/ 221 — jeez, haven’t been 175 since 6th grade!) I could completely reverse the DM and go off meds. He wants me to do this by April 2018. Oh, God. Help!

Mark R
Guest

Dear Dr. Fung, Please refrain from the “No sh**, Sherlock” and “Oh. My. God” rhetoric, and stick with the science!!! You lose credibility which we cannot afford to do in the uphill battle against conventional beliefs. When you write, “The advice to [eat constantly to lose weight] sounds really stupid, because it is really stupid,” others might easily insert [eat fat to lose fat]. Not a winsome debate!!! Your readers expect you to be more disciplined in your writings. Please!

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[…] blog post from Jason Fang about when how to eat – basically when to eat and when not to […]

Forest Simmons
Guest

The early breakfast eaters weighed less for the same reason that people who cannot produce very much insulin lose weight unless they supplement with insulin. Their urine tastes and smells sweet because their kidneys are removing the blood sugar since it cannot be stored without the help of insulin.

So eat a big high carb breakfast and pee out the sugar instead of storing it as fat.

Professor Fung can tell us if this is good for the kidneys.

Jeri Labell
Guest

Amen to an insightful read, thank you Dr. Fung for intercepting my world. As for the nit picky spelling, LOL~ Did you mean to say JESUS, when you wrote Jay-sus? If so, HE is my LORD and Savior and HIS name is to be praised, not to be used as an exclamation, along with OMG. It is written, GOD holds no man guiltless who takes HIS name in vain. #3 Commandment.

Martin
Guest

Yes, but we don’t all think like you, you see.

Joanne
Guest

I don’t believe this agrees with what Dr. Bernstein teaches for diabetics. He recommends eating on a 6-12-12 plan (breakfast 5g carbs, lunch 12 and dinner 12) because diabetics don’t process carbs as well in the morning.

Sue
Guest

He is a type 1 diabetic.

gpisabela
Guest

Actually, it does agree. It’s about eating more of your proteins and fats at breakfast, which agrees with not eating a carb-heavy breakfast.

David
Guest

The word you are looking for in paragraph five is “jibes” not “jives.”

Chewy
Guest

He meant “coincide” so jives is correct.

Jane
Guest

“Jibes” is correct according to Merriam-Webster online dictionary, but since everyone says “jives,” that word usage is also fine.

Ronna Linn
Guest

Thank you grammar police :/

Bruce
Guest
Ah well, sounds like Dr. Fung must be getting “accused” of being “religious” or maybe even, oh dear, “a Christian”!!!! Perish the thought! No great scientific mind was EVER a Christian, surely not! (uh hummm) Well, I will continue reading your stuff Dr. Fung, and praying for you. I will also humbly put forth that this is extremely common – unfortunately many great minds and wonderful thinkers and doers, great people, go this way – thinking they are above God, indeed, suppressing the knowledge of God. Face it, you, and all others, KNOW that there is God – the Bible… Read more »
Shari
Guest

Way to bring me down, Bruce! I am not sure what triggered this condescending religious diatribe but this is not the place. This is a discussion about fasting, weight, health not your Sunday school class. And your passive aggressive “I will pray for you” stuff is just…you should be ashamed of yourself.

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