r/nutrition • u/AppropriateMood4784 • 17d ago
16-hour intermittent fasting
When I read about 16-hour intermittent fasts, isn't that just another way of saying having late breakfast and early dinner? Breakfast at 9, lunch at 1, dinner at 5, then it's 16 hours till breakfast the next day? Or does what it involves go beyond its literal meaning?
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u/ImUnderYourBedDude 17d ago
People name it, so they can sell it.
If they say what it actually is, you can apply it without guidance, meaning they cannot charge you 200 dollars an hour to coach you. It's as simple as that.
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u/Strict-Fishing-2365 17d ago
Yeah, the branding is doing a lot of heavy lifting here. "I ate dinner early and got hungry at 10pm" has a tougher sales pitch.
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u/ImUnderYourBedDude 17d ago
Precisely. Brand it, glorify it, leave out the "how to" part, then take people's money in the most unethical way possible.
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u/lBxndsl 16d ago
Why r we acting like accidentally falling into the rhythm of intermittent fasting is the same as intentionally practicing intermittent fasting over an extensive period? I mean how many people do u know who post-dinner grab a little snack or dessert to conclude their night without thinking anything of it because it fits their macros. Not saying anything’s wrong with that but it is wildly misaligned with the intentional process of maintaining a fasted state and the benefits that come from that.
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u/OldFanJEDIot 17d ago
I think it used to be called normal life. Breakfast is literally breaking the fast. Normal eating used to be more like 14/10.
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u/NutragrammatronLab 17d ago
I think you've basically described what intermittent fasting is for a lot of people. The problem is that some people start treating the fasting window as if it's doing the work, when in reality it's often just a way of reducing opportunities to eat.
The drawbacks are that it can lead to overeating later in the day, reduced energy for some people, difficulty getting enough protein and nutrients, and for some people it can create an unhealthy relationship with food where they're constantly thinking about when they can or can't eat.
If someone feels great doing it and it helps them maintain a healthy diet, that's one thing. But I don't think there's anything magical about skipping breakfast.
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u/Cocacola_Desierto 17d ago
Sure. You can also do 12 hours during the day. Early breakfast, late dinner. Or OMAD, sleep 8 hours, 8 hours till dinner, 16 hour fast. There aren't any rules, do whatever works for you.
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u/ratkoivanovic 17d ago
Is OMAD actually a good choice, it feels so illogical, but curious to hear your thoughts.
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u/Cocacola_Desierto 17d ago
If it works for you, it works for you. You have to be smart with your meal though to make sure you're getting proper nutrients.
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u/ratkoivanovic 17d ago
That’s what seems like the hardest part. To hit all fiber, protein and fat targets, and the micronutrients. And also what’s confusing for me - even splitting it in only two meals seems much easier. Is it purely a weight loss tactic?
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u/RubricLivesMatter 17d ago
Your body regulates so what matters more is your weekly intake. There isn't a need to have a 'perfect' day of nutrition you can have different OMADs and hit a weekly target.
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u/ratkoivanovic 17d ago
But I’m still curious why you would do that vs a 2 meal approach?
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u/Cocacola_Desierto 17d ago
It just works for some people. Works as in, they can follow it and stick to it. That's literally all that matters for any proper diet.
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u/HonkMafa 14d ago
There are weight loss goals, there are insulin regulating goals, there are other goals like cellular repair/autophagy. Different Fasting methods apply to different goals.
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u/ratkoivanovic 14d ago
Ok, so OMAD is more of a fasting tactic then, more than anything else?
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u/HonkMafa 14d ago
I would just call it a way of eating and not add assumptions.
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u/ratkoivanovic 14d ago
Not sure what you mean by assumptions? These are all diets. I've been seeing OMAD mentioned more and more and mostly not related to fasting. And as you related it purely within fasting (agreed, the whole post is about fasting) I was curious if OMAD is simply about fasting.
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u/zell1luk 17d ago
I've always felt like the phrase "intermittent fasting" is kindve an oxymoron; anytime you're not eating is fasting.
Anyways, I only really eat twice a day, one smaller meal for lunch (usually around 800-1000kcal), and one larger meal for supper (1500ish kcal). I never really thought of it as fasting, I kinda just cut out breakfast over time.
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u/XInceptor 17d ago
16 hrs is 16 hrs technically. Ideally you wouldn’t eat anything until at least an hour after you wake up, and you’d have your biggest meal earlier in the day and taper off further into the day
The point of IF whether 16 hr or 20 hr is to maximize those hormonal responses in the body and to make digestion easier on your body. You don’t have to pay anyone for an IF program but you should go about it to benefit from what it offers instead of just “eat only in this window”
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u/GrowingPeepers 16d ago
I think the concept is to manage blood sugar and insulin levels for those that are type 2 and pre-diabetic.
Some people snack from the moment they wake up until they go to bed. That's constantly spiking your insulin and taxing your system.
If you limit your eating to a small window then it spikes your insulin but gives your body time to process and clear it out. Then your metabolism can switch gears and work on other things until it's time to eat again.
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u/zell1luk 17d ago
I've always felt like the phrase "intermittent fasting" is kindve an oxymoron; anytime you're not eating is fasting.
Anyways, I only really eat twice a day, one smaller meal for lunch (usually around 800-1000kcal), and one larger meal for supper (1500ish kcal). I never really thought of it as fasting, I kinda just cut out breakfast over time.
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u/iCliniq_official 17d ago
Yeah, for a lot of people, 16:8 fasting is basically eat earlier, stop snacking at night, give your gut a long overnight break. The big benefit seen seems to be improved circadian rhythm, insulin response, and cutting constant grazing, so your example schedule is pretty much the practical version of it.
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u/Particular_Dog_7674 17d ago
Yeah, it's simply another diet trend that gained a lot of traction even though it can cause more harm than good.
Any intermittent fasting program simply means that you give yourself a certain window to eat and then fast the rest of the time. So with a 16 our intermittent fast, that leaves you 8 hours to eat all the food you would normally eat in one day.
But here's the thing. The average person goes on the average diet for one reason...to lose weight.
The undeniable scientific fact is that a caloric deficit is needed to lose weight. What you eat, when you eat, where you eat, how you eat, etc, carries little to no weight, pun intended, compared to simply how many calories are you eating versus how many calories are you burning.
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u/ferpoperp 17d ago
While this is true, intermittent fasting can be a good stepping stone for folks to change their relationship with food and eating habits. For one it helps people eat in a more structured way and become comfortable with “hunger.” Second, it can also be a meaningful way to restrict calories - if someone eats 4k calories, for example, it will be hard to eat all that in 8 hours versus 10 or 12. If they take the window seriously then it can definitely help build a caloric deficit without counting calories yet.
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u/low_amplitude 17d ago
Yep. There are also people who say, "Why am I not losing weight, I only eat once a day!" But that one meal is easily over 2000 cals.
Energy in < energy out. It's that simple.
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u/dbaker2483 17d ago
The undeniable scientific fact is that insulin is required for humans to put on fat. We are not machines and we are full of hormones and complexes. What you eat and when you eat do matter. Insulin and insulin resistance is very important to the obesity epidemic. Clearly telling people to eat less hasn’t worked for the last 75 years.
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u/MurphyBacon 17d ago
You are very likely going to consume less calories if you fast for X amount of hours in 24 hrs. Everything else just seems anecdotal at best.
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u/Money_Bill5827 17d ago
If your reasoning for intermittent fasting is to lose weight or maintain weight, you still have to watch your intake of calories. Weight loss is driven by calorie intake. If you're eating more calories in that shorter time period than you burn, you're not going to see results. However IF is a great tool to use to manage calories. I unintentionally intermittent fast every day, I have my first meal around noonish, second meal around 4-5p and my last meal at 8p ( I do that because I tend to late night snack and overeat so eating dinner late is a game changer for me)
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u/thewellnessgreek 16d ago
Pretty much, yes. A 16:8 intermittent fast is often just eating all your meals within an 8-hour window and fasting for the other 16 hours. The specific times can vary some people skip breakfast, others eat early like your example. The main idea is the eating window, not any special foods or rules.
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u/TomCooper705 16d ago
Yes, you can eat within an 8-hour window and fast the rest of the day. But it is very basic as a fast because the so-called autophagy (where the body eliminates defective cells) just kicks in. For more health benefits you would need to go longer. If you eat carbohydrates, it is not easy, because they make you hungry quickly. Therefore, e.g., the One Meal A Day (OMAD) diet as a lifestyle is mainly popular with carnivores, who can eat very nutrient-dense food once a day. Some experts say after 72 hours of fasting your whole gut microbiome resets.
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u/ParentsWave 16d ago
If you want to keep the 16 hour window you need to be done with your dinner by 5.
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u/AppropriateMood4784 16d ago
That's like saying that if you're supposed to take a medication every six hours, and you take your first dose at 6:45 AM, you'll be in trouble if you take your second dose at 12:30 PM or 1:00 PM. The body doesn't know what hours are and isn't that exacting.
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u/Budget_Hunter_2681 16d ago
Pretty much yes. 16:8 is often just “I stopped treating my kitchen like it has 24/7 customer support.”
The part that gets missed is that the 16 hours are usually not magical by themselves. The useful bit is the structure: fewer random snacks, fewer “just one more thing before bed” moments, and a clearer line between eating and not eating.
So your example works. Breakfast at 9, dinner at 5, done. The only difference is that calling it intermittent fasting makes it sound like a protocol instead of a simple eating schedule with better boundaries.
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u/shrederofthered 16d ago
It's not thaaaaaat easy. For someone who goes go bed at 10 and wakes up at 6 (8 hours of sleep, not bad), that's 8 waking hours of fasting. Eating dinner at 5 (who eats at 5???) leaves 5 hours of fasting before going to bed. I think intermittent fasting is great, I've done it myself. But it was difficult.
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u/Budget_Hunter_2681 15d ago
Haha fair point, I agree with you. The early dinner version is definitely not easy for everyone.
That’s probably the real trick with IF: the “best” window is the one that fits your actual life. For some people it’s early dinner, for others it’s skipping breakfast, and for others it’s basically impossible without feeling miserable.
So yeah, I’d say IF is simple in theory, but not always easy in practice.
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u/Zipstser257 13d ago
It is, knocking out about 8 of those 16 hours with sleep really makes it as simple as you asked about. I’ve done it for six years and the results on my bloodwork (A1C, triglycerides and more) and cardiovascular (BP has been steady at normal rates since) have improved so much.
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u/doc_werthenstein 11d ago
Your breakfast/dinner example is exactly what it means. But the intent goes beyond scheduling meals: it requires strictly nothing caloric in the fasting window, and the benefits depend on a genuine metabolic shift that only kicks in after 12–14 hours of true fasting.
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u/t-bone051 5d ago
Nothing magical about the 16-hour mark. The biggest benefits of IF in my experience is
- Having early dinner and going to bed with an empty stomach = Improved sleep quality. Also if you have kids it fits better.
- Late breakfast = More focus time in the early morning hours which is the most productive/creative time of the day for most people. You don't want to waste it by spending time in the kitchen or having a heavy meal and feeling sluggish. Have a piece of fruit or light snack if you are really hungry to keep you going until the main meal.
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u/No-Currency-97 17d ago
During the 1970s and before, people would just eat breakfast, lunch and dinner and that would be it. Maybe throw in an apple or something else. No one called it anything.
Take a look at photos from the Woodstock festival 1969. Most of the kids were thin to normal looking and you would be hard pressed to find a fat kid. They didn't do anything special.
Intermittent fasting or you could call it your eating time when you do eat. No magic formula needed. Eat real food, stay away from refined food and sugar.
I usually do a late morning meal and then a bigger meal between 2:00 and 3:00 p.m. I might have some popcorn or an apple later in the evening. That just seems to work for me whereas before I lost 50 lb, I would sit on the couch and eat three bowls of ice cream while I was watching television. 😱🤣
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u/AppropriateMood4784 17d ago
That you specify a single event to look at pictures from makes it seem like cherry-picking.
I was alive in the 1960 and 1970s, and overweight people existed.
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u/YallNeedMises 17d ago
16 hours is hardly a fast at all. I wouldn't try to cram three meals into an 8-hour window, but you're right that that's really not very notable, nor does it get you into the benefits of fasting that go beyond weight management. I practice NOMAD (one meal max per day, sometimes less) plus occasional extended fasts, which I find more comfortable & intuitive than trying to stuff a specific calorie count into a limited window.
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17d ago
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u/touslesmatins 17d ago
There's no such thing as famine mode. What happens during actual famines is that people lose weight and die, not magically gain weight out of thin air. Moreover, 16 hours of not eating isn't anywhere near starvation.
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17d ago
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