The Critical Importance of Meal Timing for Weight Loss

There have been two main changes in dietary habits from the 1970s (before the obesity epidemic) until today. First, there was the change is what we were recommended to eat. Prior to 1970, there was no official government sanctioned dietary advice. You ate what your mother told you to eat. With the publication of the Dietary Guidelines for Americans, we were told to cut the fat in our diets way down and replace that with carbohydrates, which might have been OK if it was all broccoli and kale, but might not be OK if it was all white bread and sugar.

But the other major change was in when we eat. There were no official recommendations on this, but nevertheless, eating patterns changed significantly, and I believe contributed equally to the obesity crisis. From the NHANES study in 1977, most people ate was 3 times per day – breakfast, lunch and dinner. I grew up in the 1970s. There were no snacks. If you wanted an after school snack, your mom said “No, you’ll ruin your dinner”. If you wanted an bedtime snack, she just said “no”.  Snacking was not considered either necessary or healthy. It was a treat, to be taken only very occasionally.

By 2004, the world had changed. Most people were now eating almost 6 times per day. It is almost considered child abuse to deprive your child of a mid-morning snack or after school snack. If they play soccer, it somehow became necessary to give them juice and cookies between the halves. We run around chasing our kids to eat cookies and drink juice, and then wonder why we have a childhood obesity crisis. Good job, everybody, good job. Without any science to back it up, many nutritional authorities endorsed eating multiple times per day as a healthy practice. There were no studies that remotely suggested this was true. It was likely the successful efforts of snack food company advertising to dieticians, and doctors, clueless about nutrition at the best of times, who simply went along for the ride.

Recently Satchin Panda did an interesting study on current eating habits, tracked via a smartphone app. The 10% of people who ate the least frequently, ate 3.3 times per day. That is, 90% of people ate more than 3.3 times per day. The top 10% of people ate an astounding 10 times per day. Essentially, we started eating as soon as we got up, and didn’t stop until we went to bed.

The median daily intake duration (the amount of time people spent eating) was 14.75 hours per day. That is, if you started eating breakfast at 8 am, you didn’t, on average, stop eating until 10:45! Practically the only time people stopped eating was while sleeping. This contrasts with a 1970’s era style of eating at 8am breakfast and dinner at 6pm, giving a rough eating duration of only 10 hours. The  ‘feedogram’ shows no let up in eating until after 11pm. There was also a noticeable bias towards late night eating, as many people are not hungry in the morning. An estimated 25% of calories are taken before noon, but 35% after 6pm.

When those overweight individuals eating more than 14 hours per day were simply instructed to curtail their eating times to only 10-11 hours, they lost weight (average 7.2 pounds) and felt better even though they were not instructed to overtly change what they ate, only when they ate.

This has huge metabolic consequences. A fascinating study was recently published directly comparing a regular eating schedule to an optimized time restricted feeding schedule. Both intermittent fasting and time restricted eating tend to produce some reduction in food intake, and therefore it is never clear whether the benefits of these strategies are due to timing (when to eat) or food intake (what to eat).

The circadian rhythm, as I’ve discussed previously, suggests that late night eating is not optimal for weight loss. This is because excessive insulin is the main driver of obesity, and eating the same food early in the day or late at night have different insulin effects.  Indeed, studies of time restricted eating mostly show benefits from reducing late night eating. So it makes sense to combine two strategies of meal timing (circadian considerations and time restricted eating) into one optimal strategy of eating only over a certain period of the day, and only during the early daytime period. Researchers called this the eTRF (early Time Restricted Feeding) strategy.

This was a randomized crossover, isocaloric and eucaloric study. That is, all patients did both arms of the study eating the same foods and the same calories and then compared against themselves. The two arms of the study were eating between 8am and 8pm, and the eTRF strategy of eating between 8 am and 2pm, but remember, both groups ate 3 meals per day of the same foods. Some would start with the conventional diet, then cross over to eTRF, and others did the opposite, separated by 7 weeks washout period. Subjects were men with prediabetes.

The benefits were huge. Mean insulin levels dropped significantly, and insulin resistance dropped as well. Insulin is a driver of obesity, so merely changing the meal timing and restricting the number of hours you ate, and also by moving to an earlier eating schedule produced huge benefits even in the same person eating the same meals. That’s astounding. Even more remarkable was that even after the washout period of 7 weeks, the eTRF group maintained lower insulin levels at baseline. The benefits were maintained even after stopping the time restriction. Blood pressure dropped significantly as well, demonstrating even more metabolic benefits. Same person. Same number of meals. Same food. Far improved metabolic profile. 

But won’t the time restricted feeding group be more hungry? Sure they might be skinnier, but their poor stomachs are growling for food in the evening, right? No pain, no gain. Incredibly, it was the opposite. Those people who restricted late night eating had LESS desire to eat, but also less capacity to eat. They couldn’t eat more at night even if they wanted to! That’s amazing, because now we are working with our body to lose weight instead of constantly fighting it. It is obviously easier to restrict eating in the evening if you are not hungry.

Somewhat counterintuitively, restricting eating at 2 pm produced more feelings of fullness in the evening. Some other important lessons learned is that there is an adaptation period to this method of eating. It took participants 12 days on average to adjust to this way of eating. So don’t start this eTRF strategy and decide it didn’t work for you after a couple of days. It can take up to 3 or 4 weeks to adjust. Most found the fasting period relatively easy to adhere to, but more difficult to adjust to the time restriction.

That is, it’s not hard to fast for 16 or 18 hours. But eating dinner at 2 pm is tough. Given the modern schedule of working or school during the day, we tend to push our main meal into the evenings. The main family meal together is dinner, and this is ingrained into us. So, I’m not saying this is an easy task, but it may certainly have a number of metabolic benefits. Having a fasting support group, such as the IDM membership community, can certainly help. Fasting aids, such as green tea, coffee or bone broth can also help (although some would not consider that a true fast).

But the bottom line is this. We focus nearly obsessively on the question of ‘What to Eat’. Should I eat avocados or steak? Should I eat quinoa or pasta? Should I eat more fat? Should I eat less fat? Should I eat less protein? Should I eat more protein? Let’s face it, the answer changes every few years, according to who you ask.

But an equally important question lies almost completely unanswered. What effect does meal timing have on obesity and other metabolic parameters? Quite a lot, it turns out. Having a well defined fasting period is likely very important. The strategy of eTRF, and intermittent fasting more generally now gives exhausted dieters a new hope.

 

 

 

2018-05-29T09:23:09+00:0046 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.

46
Leave a Reply

avatar
23 Comment threads
23 Thread replies
23 Followers
 
Most reacted comment
Hottest comment thread
31 Comment authors
DaveMicahRajaniNoushinaLaura Recent comment authors
  Subscribe  
newest oldest most voted
Notify of
cem hakan
Guest
cem hakan

First 🙂

Linda
Guest
Linda

Good info to consider….Thanks for continuing to educate me.

Deborah
Guest
Deborah

This should be obvious, so why do I keep doing it? Time restricted eating only works if you don’t binge on junk food after lunch. For me it’s ice cream, cake, milk chocolate and cookies.

Jeanne
Guest
Jeanne

You are correct it is quite difficult to eat at/by2 pm and be done for the day. I will strive for 6 pm because that is hard too! I don’t eat breakfast so that’s twice a day eating, basically. I still think processed carbs (for me at least) are the devil. 47 yrs of obesity and when i gave them up the weight finally starts to come off. There has to be something to it.

Casey
Guest
Casey

Good stuff!!! Thank you

Lynn Christy
Guest
Lynn Christy

I am an experienced IF-er, keeping a daily eating window of 4-5 hrs for a keto-friendly meal + one snack. But I have “saved” that meal for 8 pm or later, for fear of having nothing left to look forward to, post-dinner.
This article is the first thing that has ever convinced me to change that. Wow! It seems really important. So now I will attempt to maximize my health benefits by moving dinner back to an early hour as often as my work schedule allows.

Micah
Guest
Micah

It’s been a month, did you commit?

Jyoti
Guest
Jyoti

Makes sense and fits with how Im feeling more comfortable and full in the evenings these days. I have a question on alchohol though. Will a glass of wine in the evening (when we’re not hungry) contribute to an insulin spike ?

JohnM
Guest
JohnM

Paraphrasing The Obesity Code, page 225, “Moderate consumption of red wine … two glass a day … does not raise insulin or impair insulin sensitivity… and is not associated with major weight gain and may improve insulin sensitivity.”

As is frequently the case in biology there are other considerations.

Several areas in The Diabetes Code describe potential liver issues – NAFLD – if the situation is compounded by the existence of metabolic syndrome.

Vadym Graifer
Guest

I am one of those who felt hunger in the evening my entire life. This changed drastically since I implemented blue light control – blue blockers after sunset time and when watching TV, software warming the computer screen light, and some more practical steps. This helped immensely; my eating window is now pretty much ending at 1-2 pm, except for occasional social event. Some days I just have largish breakfast and fast till next morning, easy and naturally.

If you have troubles controlling hunger in the second time of the day, try this corrective action for your circadian rhythms.

Mwah
Guest

How do you block blue light on TV

Vadym Graifer
Guest

By blue-blocking glasses. Unlike computers/phones/tablets, TVs do not offer screen-warming options that I’d be aware of… 🙂

Cat Hi
Guest
Cat Hi

Thanks again Jason, I have been low carb for 3 years and still struggle with prediabetes. I am now recuperating from a tummy virus and havent eaten in a few days, so now is the time for me to start this. The timing of this article has been great for me!!!!!!!!!!!!!!!!

Diane
Guest
Diane

I might have to try this, for weekends at least, as it’s impossible with my work. I found eating only between 12pm and 7pm helpful. I see the fasting triglyceride level increased and wonder if the reason for this is known.

BobM
Guest
BobM

I find it impossible to keep a schedule like this. I’m often not home until after 6pm, and if I want to see my kids at all, that’s when I see them. We eat dinner together, or try to do so. Even during the weekend, our days are busy enough that it’s difficult to eat until dinner.

Where is triglycerides increasing?

Fleur Brown
Guest

Same for my husband and me. Could not eat at 2pm as we live in the real world of work, kids, etc. Both working and not back home before 6pm during the week, and 7:00/7:15 dinner is a great time to come together with the kids,sit around the table, share our day …makes us really close as a family. We avoid breakfast and have a light lunch around 12 noon/1pm. Eat LCHF. Have gone from pre diabetes blood readings to normal, losing weight steadily and my hypertension has decreased. An intermittent fasting approach that for us works pragmatically, appears to… Read more »

Diane
Guest
Diane

Hi Fleur,
Yes we just need to steer away from the outdated guidelines and use what we can from this great advice and the other advice available like you say LCHF or some form of fasting. So much easier than the old slog of calorie restriction with low fat.

Diane
Guest
Diane

Hi Bob,
The graph – Median American Eating Pattern vs Early Time Restricted Feeding –
comment image
Accompanying the link to the study, although following the link to the summary of the study made no mention of this. I guess I need to track down the full report.
I am not being critical of restricted time feeding as I know it works for weight loss, as does intermittent fasting (like a 5 / 2 diet).

JohnM
Guest
JohnM

The link to a free dowload is identified above in the reply to juliet.

It seems the researcher missed the dawn phenomenon – “… a normal occurance..” – described by Dr Fung on page 203-204 in Diabetes Code.

Diane
Guest
Diane

Thanks for the link John.

BobM
Guest
BobM

Thank you, Diane.

Sharilyn Clay
Guest
Sharilyn Clay

Thank you so much for posting this! It was exactly what I needed to read and to share with an interested co-worker. Thank you also for all you do!

Simstar
Guest
Simstar

It’s because of you and teaching us about hormones and it’s impact that I’ve been able to shed so much weight and clear my skin. I wish I could upload a before and after pic here for you to see how you’ve literally found the fountain of youth in intermittent and extended fasting. Of course those who want to sell stuff to us consumers don’t want your message to reach others. My results, unfortunately for them, are screaming to the masses. I need a Fungster shirt. However, I do question if it’s really better to eat during the day instead… Read more »

Diane
Guest
Diane

A “Fungster Shirt”! Simstar, Dr Jason will feel like a rockstar.

juliet
Guest
juliet

Am I wrong in understanding that this eTRF study set out to test and indeed showed that reduced insulin is not necessarily linked to weight loss ? I understood that the idm approach is based on the causality of reducing insulin and weight loss. This seems to show that the two are not necessarily causally linked. If I fast and restrict eating hours my insulin markers will improve but I will not necessarily lose fat/weight? I would very much appreciate clarification please Dr Fung. Thank you.

JohnM
Guest
JohnM

To the first question it may be that the 2pm dinner tends to synchronize that meal’s insulin hit to coincide with the circadian rhythm for a synergistic effect.

To the second question given an identical caloric intake, the same coordination might enhance weight loss whereas off-sync it might not.

Would love to read the full study.

juliet
Guest
juliet

Hello John. Thanks that is useful ‘food’for thought. The full study is referenced in the blog post above. As I understand it they didn’t lose weight despite being in sync with circadian rhythm by eating 2pm last meal…

BobM
Guest
BobM

But you have to buy the study to get the complete text.

juliet
Guest
juliet

Yes you are right. I just read the abstract which was enough for me….unless the full text answers my conundrum perhaps.

JohnM
Guest
JohnM

I managed to locate and download a free, full report. https://s3-eu-west-2.amazonaws.com/2mealday.com/wp-content/uploads/2018/05/30122626/10.1016%40j.cmet_.2018.04.010.pdf The study is not at all an attempt to refute the insulin hypothesis. And the potential, say, for an optimizing merger of circadian rhythm and fasting windows was left for future studies. Also weight loss was NOT a goal for this study. The goal was to determine if the advantages attributed to intermittent fasting we’re actually caused by weight loss. So, to eliminate it as a potential confounding factor, participants were fed more to counter the weight loss they might have otherwise experienced. To me, the take home points:… Read more »

juliet
Guest
juliet

Hi John Thanks so much for this. I haven’t had time to read the full article yet . Thank you for your thoughts. I am still confused though as it seems to me that this study disproves the causality between reduced insulin and losing fat. I understood from reading the Obesity Code and the blog post above that insulin is the main driver of fat accumulation/increase in humans and this study shows that you can have reduced insulin and still maintain or increase fat. I know this was not the aim of the study but for me it seems to… Read more »

JohnM
Guest
JohnM

The “causality between reduced insulin and losing fat” was proven beyond doubt in 1921 with the cure for Type 1 diabetes.

The fact that this study had to increase calorie intake on the eRTF arm – the arm that demonstrated those reductions in insulin levels – was only necessary because they were losing weight.

Better?

juliet
Guest
juliet

John
Thank you. I can’t see your comment here but that restores my faith in the insulin : fat causality…Thank you. Yes much better! I need to read the whole study. Thank you for the link.
Juliet

Prashant Gokhale
Guest
Prashant Gokhale

Great Article. Thank you!

Roger Bird
Guest
Roger Bird

“That’s amazing, because now we are working with our body to lose weight instead of constantly fighting it.”

This is the main issue between conventional thinking/medicine and alternative healing.

Jim
Guest
Jim

You mentioned this on pages 205 – 206 of “The Complete Guide to Fasting”. This expands that nicely. Thanks for all you do to help people become more healthy. Warm regards.

Stephen T
Guest
Stephen T

If we fast overnight, I suspect that many people will find it easiest to continue the fast in the morning by not eating breakfast. I eat my first meal of the day between 11.00 a.m. and noon and stop eating at 7.00 p.m. A glass or two of wine might follow on some evenings. We don’t have to be perfect to be good. Late eating isn’t helpful, but stopping at 2.00 p.m. wouldn’t suit me at all. Dr Michael Mosley selected a 5:2 fasting pattern for no better reason than it suited him. It’s not the particular fasting pattern that’s… Read more »

Herma
Guest
Herma

The study seems to compare a 12-hour fast with an 18-hour one. Of course 18 hours is better. I would be more convinced if it compared two 18-hour protocols – breakfast&lunch vs lunch&dinner. Also, the definition of “night” is a bit vague. If it means “after dark”, I’m safe because I eat dinner around 6pm – at least an hour before it gets dark.

Cara
Guest
Cara

I have a question that’s been puzzling me for a while; if anyone can answer it, I’ll be severely grateful.

Why is that, whenever I read about extended fasting, people say ketones aren’t released until 48-72 hours, yet with intermittent fasting apparently it only takes 10-12 hours for glycogen in the liver to be depleted?

Jamie
Guest
Jamie

Your liver glycogen can only be the primary source of fuel for 10-12hrs. Not 48-72hrs.

Perhaps that 48-72hr figure comes from how long it takes for your body to get into ketosis from a ketogenic diet. The keto diet allows you to consume a little bit of carbs (which would “put more in the tank” of your liver glycogen stores) which would be why it would take longer than intermittent fasting (where no carbs are consumed).

km60
Guest
km60

Since last September I have restricted eating to a 7 hour window, from 5 a.m. to noon. I’ve lost over 70 pounds and am never hungry. I will eat this way for the rest of my life. Also a vegan.

Laura
Guest
Laura

KM 60 and all of you “Fungsters”, I too have seen a great improvement in my weight and health by IF. I have no hunger at all, doing a 10AM LCHF snack and lunch @ noonish. Then I drink ice water all day and night, feeling fantastic. I am getting ready to go OMAD this week. I have a stubborn 6 lbs to lose, and it’s coming off, and my insulin resistance is under control. I grazed 10Xs a day, always feeding, never fasting. My poor pancreas. Idiot!

Laura
Guest
Laura

km60 I’m with you, I am a convert as well. We sure burned a lot of time of eating multiple times a day, and my snacking was out of control. It is so true, the less you eat, the less you want to eat. I feel liberated! 24 yrs ago, my husband did IF (didn’t know the science it at the time, he went OMAD) and dropped 100+ lbs. He has kept if off within a few lbs, as he always compensates after a celebration cheat. Good for you on the 70+ lbs you’ve lost. My friends who have paid… Read more »

Noushina
Guest
Noushina

Fasting is the best way of weightloss.l did this and i lost 5 kgs in ten days. Due to some problems i stop my fasting but now i feel that i have to start my intermittent fasting . 18:6 .window for 3 days a week.

Rajani
Guest
Rajani

Hi

This is hugely educational. I’d like to know if coconut water (not coconut milk) is acceptable as a fasting drink. I’m vegan, so bone broth is not an option for me

Dave
Guest

Doing intermittent fasting is actually easy and I find a sleep better at night. Breakfast and lunch and then stop. I try to stop eating around 2:00pm everyday and I’m not hungry at night.