When to Eat

The big debate for decades has mostly been around what we should be eating — vegan vs. high carb, low fat vs. Mediterranean, and so on — but arguably, an equally important question is when should we be eating? Does the time of day we eat have an impact on our health? How about the frequency of meals and snacks? New research points in the direction of, yes, it likely does.

When You’re More Insulin Sensitive

Insulin sensitivity is a common term when thinking about diabetes, however, it has an impact on just about everyone. Insulin is a hormone in our bodies that is produced and released when certain nutrients are present in our blood, specifically carbohydrates and protein. When we consume food high in carbohydrates and/or protein, such as a hamburger, the pancreas responds by producing and releasing insulin into our blood stream. The insulin then helps shuttle these nutrients into our cells. When someone is insulin sensitive, insulin has a much easier time getting these nutrients into the cells.

On the contrary, when someone is insulin resistant, the cell is much less responsive to insulin knocking on its door and does not easily allow the glucose and amino acids (from protein) inside the cells. In response, blood glucose levels usually increase, and more insulin is produced. If this insulin resistant state happens too frequently and blood glucose and blood insulin remain high, it can lead to various chronic diseases such as type 2 diabetes.

Ideally, we want to be in a state of insulin sensitivity, which is easier on the body and reduces the risk of developing chronic disease.

After Exercise

Aside from what we eat, insulin sensitivity can also be influenced by exercise. Exercise has an impact on how our bodies utilize and store glucose. Glucose is the preferred fuel for the body. It requires less time, fewer metabolic processes to use, and is a quicker energy source compared to fats and protein. So, it’s no wonder that during exercise, glucose is usually the body’s go-to fuel.

Glucose is stored in our bodies as glycogen in our livers and muscles. During exercise, our bodies need glucose for the increased fuel demand, but also to maintain regular blood glucose levels for normal bodily functions. The increase with which glycogen stores are depleted is related to the intensity of the exercise performed. The higher the intensity, the more reliant the body is on glucose as its fuel. So, HIIT training and heavy weight training are two common types of exercises that deplete glycogen quicker.

When you eat a meal after glycogen-depleting exercise, you have more room in your storage. So, when eating carbohydrates that normally elevate blood glucose, more of that glucose will be transported to the liver and muscles to replete the glycogen stores instead of hanging around in the blood. So, when in a glycogen-depleted state after a workout, the same high-carb meal will produce less of a glycemic response (i.e., rise in glucose and insulin) compared to that same meal when in a glycogen-replenished state before exercising. If you’re considering having a cheat meal this week or deciding when to consume your high-carb food item, it’s likely best to do so after you work out.

Additionally, if you’re interested in increasing your body composition, a few studies have shown that exercising in a fasted state can increase your lipid (fat) oxidation. This can potentially contribute to more fat loss. Furthermore, having a post-exercise meal containing protein has been shown to increase myofibrillar protein synthesis, which contributes to overall muscle growth.

Timing your meals around exercise and planning what you will eat around that can have some positive health benefits. However, keep in mind that the response you have to that meal can also depend on the length of exercise, time of day, whether or not you have already eaten that day, how you respond to and utilize nutrients, your body composition, underlying health conditions, medications, and sleep schedule.

Early in the Day

Time restricted feeding (TRF) is a common fasting protocol used by many people for various reasons such as improved glycemic response, weight loss, and better energy. During TRF, food is consumed within a predetermined time frame, and the remaining hours of the day are spent fasting. A common protocol for TRF is to skip breakfast and not eat the first meal of the day until lunch/around noon and stop eating after dinner around 8pm, giving you a 16:8 TRF window (i.e., 16 hours of fasting and 8 hours of eating). However, recent research has come out arguing for a shift towards early TRF, or eTRF. This would mean having your first meal of the day around 8am and stopping eating around 2-4pm, depending on your feeding window. You would then skip dinner and not eat until 8am the next day.

One study took non-diabetic patients and randomized them into either the eTRF group (eating their meals from 8am-2pm) or the control group (eating their meals from 8am — 8pm). Both groups ate the same meals per day and only the feeding window was different. Results showed that the eTRF group had lower 24-hour glucose levels, lower glucose levels at night, lower insulin levels, and less glucose excretions (sharp elevations in glucose above normal). When the researchers looked at markers for circadian rhythm, they found that specific circadian clock genes such as SIRT1 and the autophagy gene LC3A were increased, and a more favorable cortisol pattern was seen in the eTRF group.

A second similar study looked at eTRF in pre-diabetic men. The experimental group restricted their food to a 6-hour feeding window and were required to have their first meal between 6:30–8:30am and their last meal no later than 3pm. The control group ate for a 12-hour period and consumed the same meals provided to the eTRF group. Results from the study showed that eTRF increased insulin sensitivity, improved beta cellfunction, lowered blood pressure and oxidative stress, and decreased the desire to eat in the evening, which may assist with weight loss and improve health overall.

Less Frequently

Meal frequency has also been a common debate topic. Arguments for 3 meals per day, 3 meals and 2 snacks, 6 small frequent meals, one meal per day and intermittent fasting are common in the nutrition world. What we have found is that even though different meal plans can work for different people, in general, we probably don’t need as much as we think.

Proponents for 5–6 small meals per day argue that continuous food keeps the metabolism running at a higher rate and helps maintain better satiety throughout the day. For some people this may be true, but a few studies have been done to challenge this argument. One study showed no significant difference in weight loss while eating 3 meals plus 3 snacks per day compared to 3 meals per day. Another study showed that eating 6 small meals per day resulted in less feelings of being full.

In addition, 5–6 meals allow for more deviation from a whole food, healthy meal plan. Eating more frequently uses a lot more willpower and provides increased temptation to eat processed snacks, dessert, and sugary beverages. So aim for 3 meals per day, or even less if you practice intermittent fasting or time-restricted feeding. Sometimes 1 or 2 meals will be enough.

Only if You’re Hungry

Many of us still remember our parents scolding us to “not leave the dinner table until our plate is clean.” Of course our parents had the best intentions, and that was likely something that was passed down from their parents, however, the ideology that finishing everything that is in front of us has given us the false sense that we will be doing ourselves harm by not keeping our bodies full of food 24/7.

On the contrary, our bodies are intelligent machines that have built-in mechanisms to provide our cells with the energy they need even in times of fasting. We keep stores of energy in our bodies in the form of glucose, or sugar (as glycogen in our liver and muscles) and fat (as adipose tissue under our skin and around our organs). When in the absence of nutrients for a prolonged amount of time, our body can break down these stores and convert them into fuel used for energy. Just think of our hunter and gatherer ancestors who sometimes went days without eating, but still had enough energy to hunt and capture their prey. They utilized their own energy stores to fuel them in the pursuit of food.

Conclusion

Along with what you eat, when you eat can have similar contributions to your health. To help reduce your risk of chronic disease, improve body composition, and optimize circadian rhythm, consider eating earlier in the day compared to later, and time your meals—especially those higher in carbs and protein—after you work out. To assist with hunger levels and prevent overconsumption, think about reducing the number of meals you have per day. Finally, no need to eat if you’re not hungry. Your body will likely do just fine without that afternoon snack.

71 comments on “When to Eat

  • Hello,
    I’ve been fasting with my first meal starting between 11:00am to 12:00pm and finishing between 5:00pm to 6:00pm. I find that best fits in with my family life, however after reading it seems I should break-fast earlier in the morning and finish early afternoon. Is this correct, if so could I still continue doing what I’m doing and it still being affective?
    Thank you 🙂

    • The two studies from the article both compared an 8 hour eating window to a 12 hour eating window, so they don’t necessarily demonstrate that eating earlier is better; they demonstrate that eating for 8 hours is better than eating for 12 hours. Until more research comes out I would stick to your current routine since it works for you.

      Alternatively, you could try moving your window earlier for a couple of weeks and see if you notice a difference, but if it doesn’t fit in as well with your routine it might be harder to stick with and might result in expanding your eating window, which is probably not beneficial.

  • Hi,
    I don’t know that I can change to eTRF. I’ve never been an early eater. I’m fine with breaking fast mid-day. After 4 years of trying I finally started 16:8 in August and I’m solid with it. I have lost 20 lbs. so far and I think I’m just fine with regular TRF. I’m ecstatic! It also fits my schedule. What I have to focus on is consistent exercise. Perhaps I will make that switch eTRF one I’m solid with my daily fitness but for now I’m good.

  • The studies cited are flawed anologies. It doesn’t prove eTDF is better than later TDF because the second group in both studies had 12 hour feeding windows. A better comparison is comparing one group skipping breakfast to another group who skip dinner.

  • Hi, can someone explain me what exactly time I have to start my fasting of 16/8? I read so many things about it , a this point I’m really confused

  • I have tried eTDF and TDF later in the day. We socialize often so later TDF works best for me. I IF from 8pm to 12-2pm. I have not noticed a difference in how I feel. I think the more convenient and comfortable we find our fasting the more success we will have.

  • I’ve been using TRF for 20 years. Currently I’m on 23:1, I have one meal a day, and it’s in the evening, because I do my exercise session in the gym in the afternoon (and I can’t physically exercise after eating).

    Agreed. Do what suits you. The best thing about TRF is that it makes me immune to temptations. I’d never think of having sweet or fatty foods during the day if it’s outside my one hour window.

    • Well… Talking from my own experience… I fast almost everyday, between 16 and 24h. I do not care much about the feeding window, that can be whenever I end the fast. Most importante is surely to stick and respect the fasting period. My results have been considered great, IMO. 15 kg lost in just 45 days. I also workout lightly just twice a week, unfortunately.

    • I would imagine that the point is to have a restricted eating window. For TRF, whenever you have completed what would be your dinner is the beginning of your fast with no snacking afterwards. Then you sleep through a significant portion of your fast and don’t eat again until your fasting period is complete. Basically, you fast exactly the same way as everyone who is not a night shift worker, you just rotate the hours. Hope that makes sense.

      • I’m a night shift worker as well. 6pm-6am. I sleep from 7:30am to 3pm usually. My eating window goes from 4 pm to 12 am. I’ve lost weight and feel good. I don’t excersise and my job would be considered an office job. My sleep schedule is not consistent because my first day off I will sleep from around 7:30 am to 11am however I stick to my fast schedule. I’m not sure of the health benefits due to my sleep schedule being non consistent

    • I work night shift 1830-0700. Sleep from about 0900-1530. Start my eating period between 1600-1700 right after working out, start fasting between 2300-0000. Averages 16:8, sometimes turns out 18:6. On days off I start eating a little earlier, maybe 1400, and end 2200. Make adjustments as needed while trying to stay as close to the same as possible.

  • I just started intermittent eating and this was my second day. I fast from 12 midnight to 3pm the next afternoon. I’m counting that to be 3 hrs. 15 hrs. I eat regular meal with saving some for later, small snacks every 2/3hrs till bedtime. I’ve been able to wait all day without craving excited this is going to work. Am I doing this right? Surprise I’m not nearest Hungry and feel like I’m making progress also I weight every morning is this wise?

  • Please help. I am a retired teacher that now travels for an education company.
    1. Never the same days
    2. Never the same amount of days per week
    3. Some accounts require me to get up around 5 am and drive 2 hours. Some need me to get up around 6 am.
    I need help with best plan

    • I wouldn’t get too hung up with the exact time of your eating window. I don’t think it matters if it alters by an hour or two from day to day. My days are also very different. Sometimes I fast 16 hours, sometimes 18, sometimes 14 because I feel I need to grab something to eat whilst I can.
      If you are concerned about driving on an empty stomach have an early eating window.
      I worried about being able to function in the mornings without food (also a teacher), but after a few days I was so used to it that I don’t think about it and I can honestly say my head is clearer and energy levels are up. And I wouldn’t have any problem with driving for a couple of hours as long as I’m well hydrated.
      Hope that helps.

    • Hi Valerie,

      It really all depends on the duration of intermittent fasting you are trying to accomplish. If you are doing 16:8 and are ending your eating at 6pm, then you can start eating at 10:00am each day. You will then be fasting from 6pm to 10:00am for a 16 hour fasting window.

  • Are there any studies that show the difference between eTRF and TRF where participants skip dinner? Your article claims eTRF is better, but in both studies the control seems to be people eating 12-12.

  • Hello, im new to fasting and in the middle of trying an 18:6 . 6am brkfast 12pm lunch but I lift weights at 7pm to 830pm. What is recommended for this type of schedule? Ive read it is optimal for the 18:6 eat in the morn and fast in the evening. What is recommended in this instance? Any advice

  • I am new to fasting. Can I fast a few days a week to begin, then add more fasting days or will I not see results unless I do at least ??? days a week?

    • I would advise not to worry too much about “results” (are you aiming for weight loss?) to begin with – focus more on establishing a habit and being conscious of how you feel during this time. A few days a week is a great start – set your timer every day anyway to see how your pattern develops. Build up as you feel is best over time. Good luck!

  • I read somewhere that you need to start on a keto diet to make your body fat adaptive before intermittent fasting will work. Has anyone tried it, and how true is this?

    • My view is that keto is just a fad, and intermittent fasting is a strategy for avoiding temptation outside your non-fasting period, and may reduce your calories consumed.

      It may also be more natural, because humans didn’t evolve to have three meals a day, plus snacks.

      I have been using intermittent fasting for around 20 years, and currently I’m on an extreme 23:1 (I have one meal a day, at around 1-2 pm), and consume all the calories I need in 30-45 minutes, so if I had 2 meals over 6 hours I could easily exceed my needed daily calories, and gain weight.

      The possible health effects is an extra plus, but not one that causes me to stick to intermittent fasting. I feel better using it, than not.

  • Our Parents statement of, “eat everything on your plate “ was ok because we didn’t have all the snack throughout the day and we were outside more riding bikes, climbing trees, etc. I’m today’s society, we not only have 3 full meals a day, but snacks throughout the day with less active activities.

    • I think there was also an element of our parents generation having experienced poverty at various levels and wanting us as children to understand that our plate of food was all there was so to be grateful and make the most of it! But I agree, snacks between meals were simply not a thing when I was a child.

  • So I am going to start 16/8 from 1-2 to 800
    I have to do coffee stevia is what I plan to use and cinnamon is there anything else I can do with my coffee 😱😱😱

    • Not a pro in IF just yet but i did look up coffee options and almond milk is allowed! It’s low in carbs/kcal, so it doesn’t count as food when used in moderation

  • I am an intermittent faster
    I only eat between 4 pm and 9 pm.
    Can I however have morning coffee at 6 am?
    With or without skim milk?

  • I want to start IF but my fasting hours are irregular. In the week I can fast from about 8 pm to 9 am but during weekends it from about 11pm to 12 am – does it still count as fasting?

  • The key for me is, find a routine/eating window you can be consistent with. If eTRF suits your lifestyle then great, but if regular TRF from late night to following afternoon is more convenient you are more likely to stick to it, and get results.

    I did 5:2 consistently for a year and it became completely normal for me, but I had to stop for other health reasons. I’m starting back with 16:8 (10pm – 2pm) aiming for 4-5 days a week and it’s feeling pretty easy so far. I really appreciate the routine of setting a timer every day regardless of whether I’m aiming for a 16 hour fast. Anything that keeps me focused is a great help!

  • What kinds of foods are people eating when they fast? Actual meals? Soups? Salads? Do you eat something at any time during the eating window?

  • I work at night. 12am-9am and I struggle to stick to one schedule. Oftentimes I move my fasting hours. Right now, what i follow is:

    Feasting: 2am-10am
    Fasting: 10am-2am

    Any suggestions on how to improve this?

    • I usually start my fast at 4 pm (cutting out dinner) and stop around 8 am. this works best so i can eat my breakfast in math class (this is best for my scedule) but i don’t know what your schedule is like

  • You could use the same eating window every day. You will judy be fasting longer during awake states some times. Hope that helps.

  • Good day. I’m a newbie to intermittent fasting. I would like to start my health regime with intermittent fasting. Any advice would be appreciated. Thank you!

  • So I’m new to fasting. I’ve been doing 11-7 or 12-8. However, I prefer to workout in the mornings at 5:30. Should I adjust or am I okay with doing it this way? I have not yet incorporated my workouts as I have been making my lifestyle change insteps. First going pescatarian 5 weeks ago to intermittent fasting 2 days ago

  • Hey, i’ve got a question. Is there anything that i can eat during the fasting period; like cucumbers or oranges?
    thankyou

    • No. Water and black coffee is all you can have if you want to do it right. Perhaps a black tea but I’d stick to coffee and WATER

  • Hey guys!

    I’m training at a thaiboxing gym, so unfortunately I can’t schedule my workouts myself. I’ve been going for a trf protocol from 13.00 to approx. 22.30. The training is usually at 20.00. After I get home, eat and then my fast starts. I’ve been thinking about switching to eTrf trouble is tho, this would leave me without a post workout meal. Any thoughts or Infos about the pros and cons of that?

    Thanks!

  • I’m doing IF 16:8 but I work out in the evening and I don’t have enough energy since I stop eating by 6pm. Is it better to work out without eating? Or should I change my times to stop eating later
    Eating window is 10-6

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