Intermittent fasting is one of the easiest and healthiest lifestyle changes available to us without extensive preparation.
Unlike conventional diets, intermittent fasting saves time and money instead of filling your daily schedule and fridge with new stuff.
Since recent studies have proven the health benefits of intermittent fasting, it is more popular than ever.
However, there are different types of fasting, and not all of them are suitable for every person – especially beginners.
This scientific guide will help you find an intermittent fasting schedule that fits your lifestyle.
What is Intermittent Fasting?
Intermittent fasting (IF) has become the most popular form of fasting due to its scientifically proven benefits.
It involves eating within a certain period and fasting for the rest of the day.
Countless forms of intermittent fasting exist, and we’ll take a closer look at them shortly. Among them, the most popular daily plan involves fasting within a time window of around 16 hours.
In short, there are two main reasons to start intermittent fasting:
- Weight loss
- Health benefits
In this regard, the hormonal balance of our bodies is essential for both goals.
Because fasting is the best way to lower insulin levels, people successfully lose weight as a result.
Insulin is responsible for signaling cells to take up glucose from the bloodstream and storing excess energy as fat or glycogen.
Accordingly, researchers can already predict 75% of the gain and loss in overweight people using insulin levels (Kong et al. 20131).
In addition, insulin prevents the breakdown of body fat (Meijssen et al. 20012).
On the other hand, a fasting period stops nutrient intake and lowers insulin levels, thus ending the body’s storage mode.
Hence, the body can break down stored carbohydrates (glycogen). Once glycogen stores are empty, body fat can be burned for energy instead (ketosis).
The second primary driver of the health benefits of fasting is autophagy.
When nutrient intake and insulin levels drop, this intracellular recycling system kicks in, breaking down broken cellular parts and funneling toxins out of the body
This finding was even awarded the Nobel Prize in Medicine (Levine et al. 20173).
For example, fasting improves:
- Mental clarity and cognition (Witte et al. 20091)
- Life expectancy (Catterson et al. 20182)
- Immune function (Cheng et al. 20143)
- Muscle growth (Ho et al. 19884)
- Mood (Solianik et al. 20165)
However, not all methods offer the same benefits, as duration and frequency of fasting are determinants of fat burning and autophagy.
Intermittent Fasting Types and Plans
Intermittent fasting methods are as individual as those people who use them.
Therefore, there exists a colorful variety of intermittent fasting protocols that can have significant differences. Sensibly, different eating plans also have individual advantages and disadvantages.
Let’s explore together what characteristics the different intermittent fasting types have and what advantages and disadvantages they bring to your daily schedule.
12/12 Intermittent Fasting Schedule (Circadian Rhythm)
Let’s start with the simplest method – overnight fasting. It consists of fasting for 12 hours every day. According to this, it is not so much fasting but eating within a specific time frame.
The duration of 12 hours makes the three classic meals of the day feasible. After that, you stop snacking, which is already a significant step in the right direction for most people.
For example, you stop eating after dinner at 8 PM and don’t ingest any calories until 8 AM with breakfast the following day.
Since it is easy to do, this method can be a gentle introduction to the world of intermittent fasting. In the end, you don’t have to skip any meals but give up snacks before going to bed.
However, this schedule does not take full advantage of the benefits of intermittent fasting. The longer the fasting period, the more significant the fat loss.
In addition, the health benefits of autophagy do not become apparent until about 14 hours of fasting (Yang et al. 20179).
A modification of overnight fasting is intermittent fasting according to the circadian rhythm. This biorhythm is an internal clock that runs 24 hours and regulates our energy levels based on the day and night rhythms.
So when you fast according to the circadian rhythm, daylight sets the timeframes. As soon as the sun rises, the eating period begins. With the sunset, on the other hand, the fasting period starts.
However, this intermittent fasting schedule only makes sense if you don’t live too close to the north or south pole. There the eating window would last partially for months.
However, the classical 12/12 intermittent fasting pattern is simple:
- Fasting window: 12 hours
- Eating window: 12 hours
16/8 Intermittent Fasting Schedule (Time-Restricted Eating, 14/10, 18/6)
Although various forms of intermittent fasting exist, by far the most popular is eating within a window of about 8 hours.
Classic 16/8 intermittent fasting is also known as the Lean Gains Method, Time-Restricted Eating or Peak Fasting because it allows you to gain muscle mass while losing body fat.
Hence, even bodybuilders have been using classical 16/8 fasting for decades.
As the name time-restricted eating suggests, this method is the mother of many intermittent fasting schedules. It specifies a strict time each day during which eating is allowed. During the rest of the day, however, you strictly fast.
For example, you eat between noon and 8 PM. This way, the body can fast for 16 hours with an 8-hour eating period in between. Since you sleep 8 of the 16 fasting hours, classic intermittent fasting is more convenient than you might think.
Depending on your daily routine, you can also successfully use this intermittent fasting method with a 14/10 or 18/6 schedule or even approach more extended periods. However, the most popular intermittent fasting schedule remains as follows:
- Fasting window: 16 hours
- Eating window: 8 hours
20/4 Intermittent Fasting Schedule (Warrior Diet)
The Warrior Diet is also a modification of the 16/8 fasting plan. It got its name from Ori Hofmekler, whom we can call a pioneer in the field of intermittent fasting.
Finally, the Warrior Diet was one of the first popular diets that included a form of intermittent fasting.
On the 20/4 schedule, you fast throughout the day and feast bluntly in the evening within a 4-hour window.
Unlike other methods, you can eat small amounts of raw fruits, vegetables, and lean protein on the Warrior Diet during the 20-hour fasting period.
However, I would not recommend this snack interlude to anyone. Low-fat protein and carbohydrates stimulate insulin secretion, thereby interrupting fat burning and autophagy.
Otherwise, food choices on the Warrior Fasting Protocol are related to the Paleo Diet. In any case, natural, unprocessed foods are a step in the right direction.
Hence, this intermittent fasting schedule is based on the idea that our ancestors hunted and gathered during the day and prepared a big meal at night.
Therefore, in the Warrior Diet, the 4-hour eating window is in the evening. Furthermore, the notion of following a specific order when eating food makes perfect sense.
On the Warrior Diet, you eat vegetables, protein, and fat first. Carbohydrates are only optional if you’re still hungry afterward.
- Fasting window: 20 hours
- Eating window: 4 hours
23/1 Intermittent Fasting Schedule (OMAD)
One Meal A Day (OMAD) is not a diet but rather a more extreme form of the classic 16/8 intermittent fasting schedule. By limiting the eating window to one meal, it represents the step up from the Warrior diet.
Therefore, OMAD means nothing more than that you only eat once a day and fast the rest of the day. With this in mind, OMAD is not the proper method for beginners.
Hence, OMAD can be a situational method for people who have been fasting with the 16/8 schedule for a while.
In my opinion, this is one of the most significant advantages of fasting. It’s tremendously flexible. If you are busy and just in the workflow, you skip lunch, gain time, and 16/8 becomes OMAD without additional effort.
Accordingly, OMAD is similar to 16/8 and 20/4 intermittent fasting and is also called the 23/1 method or 23/1 diet.
Anyway, with the following schedule, OMAD is even simpler than 16/8 intermittent fasting:
- Fasting window: 23 hours
- Eating window: 1 hour
Crescendo Fasting Schedule
Unlike OMAD, the Crescendo Method is a weakened form of 16/8 Intermittent Fasting.
Instead of daily fasting, you fast on several days throughout the week. For example, this can be every odd working day: Monday, Wednesday, and Friday.
It is especially suitable for starting intermittent fasting. You can test how your body and its hormonal balance react to the change.
For this reason, Crescendo Fasting is also known as a popular beginner’s method for women. Provided you feel comfortable, you can then gently approach the 16/8 intermittent fasting daily schedule.
- Fasting window: 12-16 hours
- Eating window: 8-12 hours
24-Hours Intermittent Fasting Schedule (Eat-Stop-Eat)
Another beginner-friendly option is to limit fasting to one day of the week.
24-hour fasting is also known as the Eat-Stop-Eat Schedule. Brad Pilon, another pioneer in the field of intermittent fasting, is responsible for naming this method.
Eat-Stop-Eat has been a popular intermittent fasting daily plan for several years. It involves fasting once or twice a week for 24 hours. For the remaining time of the week, you eat as usual.
For example, you fast from 8 PM on Monday after dinner until you eat dinner again on Tuesday at 8 PM.
However, this schedule is flexible, so you can also fast from breakfast to breakfast or from lunch to lunch.
Unlike the common 5:2 intermittent fasting, no small snack is allowed in this schedule. With Eat-Stop-Eat, you always fast strictly, which also makes it an effective method.
However, this is also a possible disadvantage of this fasting plan. Strict 24-hour fasting is difficult to achieve for many people – especially beginners.
Therefore, it makes sense to start with a shorter fasting window. You can comfortably begin with 14-16 hours and slowly work your way up to 24 hours.
As with other intermittent fasting schedules, the general rule is that natural, unprocessed foods with high nutrient density are essential during meal periods.
However, since a 24-hour fast may only have a single night in the fasting window, you’ll still eat every day of the week.
While this may sound beneficial, there are some disadvantages. Finally, it is easiest to fast while sleeping. Therefore, we are tackling an intermittent fasting plan next that is making use of this fact.
The weekly Eat-Stop-Eat schedule is as follows:
- Fasting window: 24 hours (1-2x)
- Eating window: Rest of the week
36-Hours Intermittent Fasting Schedule (6:1 Diet)
If you can fit two nights into the fasting period, it has enormous benefits. In the end, you are already sleeping about 16 hours of the fasting period, leaving only 20 hours to fast actively.
If you fast over two nights, the 1-day fast extends to a fasting period of at least 36 hours. For example, this corresponds to the time from dinner to breakfast the day after next.
Since you do not eat for an entire weekday, this schedule is also called the 6:1 Diet. However, contrary to popular belief, I do not recommend eating a snack between meals.
This way, you can benefit more from the anti-aging effect of autophagy and burn body fat much more efficiently for energy. To nullify this effect with a snack cannot be the goal of the effort.
We will take a closer look at the 5:2 diet for more details on small meals during fasting.
Especially for athletes and people who don’t want to restrict themselves daily, a 36-hour or 1-day fast with the following schedule is a popular option on a rest day:
- Fasting window: 36 hours
- Eating window: rest of the week
5:2 Intermittent Fasting Schedule (Fast Diet)
In the standard version of the 5:2 Diet, calorie intake is limited to 500 calories per day for two days per week (two meals of 250 calories each).
The remaining five days of the week, you eat as usual. For example, you could eat only 500 calories per day on Tuesday and Friday and normally eat Wednesday through Sunday.
For this reason, in the 5:2 Diet, you practice 36-hour fasting with a small meal twice a week. Eventually, you are turning a 6:1 into a 5:2 plan.
Although it may seem easier to approach fasting with small meals at first, it destroys the results.
If the insulin level rises due to the meal, you inhibit fat burning, autophagy, and associated health benefits.
Moreover, small meals will not satiate at all and instead initiate cravings. This fact is especially actual with carbohydrate-based foods, which spike blood sugar.
Since the hunger hormone ghrelin decreases with fasting duration, it is wiser to fast without a snack (Natalucci et al. 200510).
In my opinion, it is therefore far better to fast strictly through the two days. This way, you give the digestive tract a well-deserved break, cleanse the body, and most importantly, you will burn body fat much more efficiently.
In addition, it is even more efficient for cell renewal to fast for two days in a row. However, this duration is not suitable for beginners.
Moreover, if you do not eat for two whole days, you will have a fasting window of about 60 hours from dinner to breakfast.
Fasting periods longer than 48 hours are called prolonged fasting. You better apply such methods selectively than to put the body thereby weekly under additional stress.
Nevertheless, such a strict version of the 5:2 Diet can significantly impact fat burning and autophagy if you are an experienced fasting enthusiast.
However, the typical 5:2 intermittent fasting schedule is composed as follows:
- Fasting window: 2×1 days (small meals)
- Eating window: 5 days of the week
Alternate-Day Fasting (ADF) Schedule
This method is just as simple as it sounds – eat one day, fast one day.
However, most people eat a small meal (about 500 calories) on a fasting day. Therefore, although it is relatively widespread, this method is not a favorite of mine.
Not only does a small meal make you hungry, but it also negates the health benefits of autophagy.
In addition, Alternate Day Fasting (ADF) is more difficult for most people to incorporate into their daily routine than other plans.
In addition, many people abuse ADF because they think it allows them to maintain their Standard American Diet (SAD), dominated by refined carbohydrates.
That’s why this type of intermittent fasting is usually not successful. Because what you eat does matter a lot, even with intermittent fasting. In the end, it is always a matter of lowering the insulin level in the long term.
Moreover, poor quality food can cause unpleasant side effects more easily, making it challenging to stick to the fasting schedule.
Thus, the ADF plan is not at all suitable for beginners. However, this intermittent fasting schedule is also amazingly straightforward:
- Fasting window: 24 hours (small meal)
- Eating window: 24 hours
Intuitive Fasting (Spontaneous Meal Skipping)
An intuitive approach to intermittent fasting is possible for different starting points.
On the one hand, it can be a gentle introduction to intermittent fasting for you before you get used to a more restrictive daily schedule.
On the other hand, with 16/8 intermittent fasting, for example, you can skip lunch and sniff out an OMAD schedule if you’re too busy for a meal.
Ultimately, intermittent fasting helps you regain a natural intuitive sense of when your body is craving food. If you’re not hungry at lunch, you don’t have to force yourself to eat.
Most of our eating habits are learned and by no means need to reflect an optimum of food intake.
Plus, cooking and eating takes an enormous amount of time. Skipping meals gives you more time to do other things, like meeting friends or going for a walk.
Spontaneously skipping meals is an effective way to revise the widely held belief that we need to eat three meals a day. Accordingly, you won’t starve to death if you skip a meal now and then!
Likewise, you won’t automatically overeat as soon as you eat afterward. These and other conventional concerns have already been debunked by science.
You can read more about this in my article on the top 10 myths of intermittent fasting.
How to Find the Best Method for Beginners
Although approaches exist that fit most people, it’s perfectly reasonable to experiment in the beginning.
After all, your body and daily schedule are unique, so it’s not always the same method that can best fit that routine.
For example, you can start slowly with a 12/12 day plan, as this is an effortless way to get started for most people.
You stop eating a few hours before bedtime and postpone breakfast for a few hours after waking up.
If that works well, extend the fasting window the next day and repeat the process until you arrive at a daily schedule that works for you.
Since you have to subtract 8 hours of sleep, 12 to 16 hours is not long to wait for a meal. Accordingly, it’s easy to experiment with classic intermittent fasting, where you still eat every day.
Best Intermittent Fasting Schedule for Weight Loss
Since fasting is the most effective way to lower insulin levels, many people successfully lose weight.
Once you get used to an intermittent fasting daily schedule, the hunger hormones adjust to the plan, and fasting should become almost effortless.
For example, the essential hunger hormone ghrelin decreases as the duration of fasting increases and only increases in a pulsatile manner when we expect a meal (Natalucci et al. 200513).
Therefore, people with a fixed intermittent fasting schedule tend to succeed more than people with irregular eating patterns.
With this in mind, 16/8 intermittent fasting is the best schedule for most people to lose weight successfully.
The ease of use makes 16/8 a guarantee of success. You only have to cut out one meal and unnecessary snacks. Due to the beneficial hormonal balance in the morning, it is easiest to skip breakfast.
However, people can also achieve success by skipping dinner if it fits better into their daily routine.
16/8 intermittent fasting guarantees a period of low insulin levels every day, while the method does not drastically change the daily routine.
This balance results in most people being able to stick to the daily schedule as well. And finally, continuity is the key to realizing results.
While working out might be helpful for weight loss, people overestimate its impact. Sticking to a low-carb diet is far more critical to allow insulin levels to sink in the first place.
If you want to put the icing on the cake, you can integrate two short but intense weight lifting sessions into your weekly schedule.
They help empty carbohydrate stores and get you into ketosis, and thus burning fat faster. For best results, train in a fasted state. For more details, please read my article on intermittent fasting and exercise.
Best Intermittent Fasting Schedule for Women
Nature is interested in reproduction before anything else. Therefore, the female body always focuses on producing healthy offspring that survive and do the same.
From this evolutionary perspective, a woman’s situation is even more precarious than that of a man. Finally, periods of hunger or other stress can jeopardize the health of the offspring.
For this reason, female hormones are more sensitive to changes in diet and other external circumstances, so they are better able to adapt.
For example, the hunger hormone ghrelin can rise again more quickly after a meal in women than in men. Therefore, slightly shorter fasting windows of 12-14 hours instead of 16 hours often provide a more successful start for women.
For this reason, crescendo fasting is known as the starter plan for women. Here, you can approach your ideal fasting schedule in two dimensions.
On the one hand, you can gradually increase the fasting window of the daily plan from 12 to 14 to 16 hours. On the other hand, the weekly plan calls for intermittent fasting only every other day.
Furthermore, you can also increase this dimension slowly to a whole week. In addition, many women also have success with limiting fasting to weekdays only. That way, you’re not restricted on weekends when free time and social interactions are paramount.
However, continuity makes all the difference when it comes to losing weight. That’s why it’s a good idea to establish a fixed fasting window, at least on weekdays, after a one-month introductory phase.
With this in mind, choose your fasting window wisely, so you can and will stick to it during your daily routine.
Best Intermittent Fasting Schedule for Men
For most men, in my experience, it is possible to start directly with a 16/8 fasting plan. Finally, you will unlearn appetite in the morning in less than two weeks.
In addition, 24- or 36-hour fasting is also excellent for men, as they find it easier on average to fast for more extended periods at a time.
Those who are athletes and do not like to restrict themselves in everyday life are best served with 36-hour fasting. Because two nights lie in the fasting period, this method is feasible weekly and effective for health goals.
Men who have been engaged in intermittent fasting for a long time also tend to use more extreme methods more often.
People who travel a lot or have a physically active working day can optimize their health by skipping lunch.
So 16/8 becomes a 20/4 or OMAD fasting schedule. In any case, the daily routine must fit to increase the fasting window from 16 hours to 20 or more.
I practice OMAD, especially when I want to maximize productivity and free time. There is no question that lunch brings losses in concentration. Still, it has social benefits and may reduce stress on your working day.
Intermittent fasting is more than just a weight-loss tool. As long as you practice it correctly, it is the simplest way to establish a healthy lifestyle.
Nevertheless, it is not possible to start intermittent fasting successfully with every schedule.
For example, the 16/8 fasting plan is popular because it can realize health benefits while being simple and hardly restricting.
Nonetheless, even with intermittent fasting, the quality of your diet is crucial.
If your eating window is filled with processed carbohydrate-rich foods, you won’t lose weight or improve your health.
Moreover, there are situations in which fasting is inappropriate. These include, in particular, times of pregnancy, breastfeeding, eating disorders, or chronic stress.
Furthermore, before you start fasting, you should consult the doctor you trust.
What is a good schedule for intermittent fasting?
The 16/8 schedule is the most popular intermittent fasting plan for a reason. While you only need to cut out breakfast and snacks, you will see results pretty soon.
How much weight can you lose in a month with intermittent fasting?
In my experience, an average person who is slightly overweight can lose about 4-8 pounds in a month with intermittent fasting.
Is 12 hours between meals considered intermittent fasting?
While it’s not the most effective schedule, this plan is known as 12/12 intermittent fasting.
What should I eat during intermittent fasting?
Generally, intermittent fasting does not prescribe any foods. However, you’ll get the best results with a low-carb diet like the keto diet.
Studies Click to expand!
1Kong LC, Wuillemin PH, Bastard JP, Sokolovska N, Gougis S, Fellahi S, Darakhshan F, Bonnefont-Rousselot D, Bittar R, Doré J, Zucker JD, Clément K, Rizkalla S. Insulin resistance and inflammation predict kinetic body weight changes in response to dietary weight loss and maintenance in overweight and obese subjects by using a Bayesian network approach. Am J Clin Nutr. 2013 Dec;98(6):1385-94. doi: 10.3945/ajcn.113.058099. Epub 2013 Oct 30. PubMed PMID: 24172304.
2Meijssen S, Cabezas MC, Ballieux CG, Derksen RJ, Bilecen S, Erkelens DW. Insulin mediated inhibition of hormone sensitive lipase activity in vivo in relation to endogenous catecholamines in healthy subjects. J Clin Endocrinol Metab. 2001 Sep;86(9):4193-7. doi: 10.1210/jcem.86.9.7794. PubMed PMID: 11549649.
3Levine B, Klionsky DJ. Autophagy wins the 2016 Nobel Prize in Physiology or Medicine: Breakthroughs in baker’s yeast fuel advances in biomedical research. Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):201-205. doi: 10.1073/pnas.1619876114. Epub 2016 Dec 30. PubMed PMID: 28039434; PubMed Central PMCID: PMC5240711.
4Witte AV, Fobker M, Gellner R, Knecht S, Flöel A. Caloric restriction improves memory in elderly humans. Proc Natl Acad Sci U S A. 2009 Jan 27;106(4):1255-60. doi: 10.1073/pnas.0808587106. Epub 2009 Jan 26. PubMed PMID: 19171901; PubMed Central PMCID: PMC2633586.
5Catterson JH, Khericha M, Dyson MC, Vincent AJ, Callard R, Haveron SM, Rajasingam A, Ahmad M, Partridge L. Short-Term, Intermittent Fasting Induces Long-Lasting Gut Health and TOR-Independent Lifespan Extension. Curr Biol. 2018 Jun 4;28(11):1714-1724.e4. doi: 10.1016/j.cub.2018.04.015. Epub 2018 May 17. PubMed PMID: 29779873; PubMed Central PMCID: PMC5988561.
6Cheng CW, Adams GB, Perin L, Wei M, Zhou X, Lam BS, Da Sacco S, Mirisola M, Quinn DI, Dorff TB, Kopchick JJ, Longo VD. Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell. 2014 Jun 5;14(6):810-23. doi: 10.1016/j.stem.2014.04.014. PubMed PMID: 24905167; PubMed Central PMCID: PMC4102383.
7Ho KY, Veldhuis JD, Johnson ML, Furlanetto R, Evans WS, Alberti KG, Thorner MO. Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. J Clin Invest. 1988 Apr;81(4):968-75. doi: 10.1172/JCI113450. PubMed PMID: 3127426; PubMed Central PMCID: PMC329619.
8Solianik R, Sujeta A, Terentjevienė A, Skurvydas A. Effect of 48 h Fasting on Autonomic Function, Brain Activity, Cognition, and Mood in Amateur Weight Lifters. Biomed Res Int. 2016;2016:1503956. doi: 10.1155/2016/1503956. Epub 2016 Nov 29. PubMed PMID: 28025637; PubMed Central PMCID: PMC5153500.
9Yang JS, Lu CC, Kuo SC, Hsu YM, Tsai SC, Chen SY, Chen YT, Lin YJ, Huang YC, Chen CJ, Lin WD, Liao WL, Lin WY, Liu YH, Sheu JC, Tsai FJ. Autophagy and its link to type II diabetes mellitus. Biomedicine (Taipei). 2017 Jun;7(2):8. doi: 10.1051/bmdcn/2017070201. Epub 2017 Jun 14. PubMed PMID: 28612706; PubMed Central PMCID: PMC5479440.
10Natalucci G, Riedl S, Gleiss A, Zidek T, Frisch H. Spontaneous 24-h ghrelin secretion pattern in fasting subjects: maintenance of a meal-related pattern. Eur J Endocrinol. 2005 Jun;152(6):845-50. doi: 10.1530/eje.1.01919. PubMed PMID: 15941923.
11Kong LC, Wuillemin PH, Bastard JP, Sokolovska N, Gougis S, Fellahi S, Darakhshan F, Bonnefont-Rousselot D, Bittar R, Doré J, Zucker JD, Clément K, Rizkalla S. Insulin resistance and inflammation predict kinetic body weight changes in response to dietary weight loss and maintenance in overweight and obese subjects by using a Bayesian network approach. Am J Clin Nutr. 2013 Dec;98(6):1385-94. doi: 10.3945/ajcn.113.058099. Epub 2013 Oct 30. PubMed PMID: 24172304.
12Meijssen S, Cabezas MC, Ballieux CG, Derksen RJ, Bilecen S, Erkelens DW. Insulin mediated inhibition of hormone sensitive lipase activity in vivo in relation to endogenous catecholamines in healthy subjects. J Clin Endocrinol Metab. 2001 Sep;86(9):4193-7. doi: 10.1210/jcem.86.9.7794. PubMed PMID: 11549649.
13Natalucci G, Riedl S, Gleiss A, Zidek T, Frisch H. Spontaneous 24-h ghrelin secretion pattern in fasting subjects: maintenance of a meal-related pattern. Eur J Endocrinol. 2005 Jun;152(6):845-50. doi: 10.1530/eje.1.01919. PubMed PMID: 15941923.