If you’ve looked into intermittent fasting, it’s likely you’ve come across the 16:8 fasting approach, one of the most popular and widely studied fasting methods. It is appealing to many novice and experienced fasters alike as it’s simple, flexible, and less extreme than several other fasting protocols.
With 16:8 fasting, you fast for 16 hours of the day and eat during an eight-hour window. Over time, this fasting method is associated with weight loss, improved blood sugar and heart health markers, cognitive health, and more.
But how quickly can you expect to see these benefits? In this article, we’re breaking down what to expect after 1 month of fasting on an intermittent schedule. We’ll also provide a typical fasting weight loss timeline and offer guidance on approaching 16:8 safely and sustainably.
What Is 16:8 Fasting?
16:8 is a form of intermittent fasting that involves a daily fast of 16 hours and an 8-hour eating window. Common schedules include eating from 11-7 pm or 12-8 pm, though you can make it fit your own routine. Compared to other fasting methods, 16:8 is usually more sustainable because it doesn’t require prolonged fasting windows and can fit more nicely into a daily schedule.
During fasting times, only calorie-free or very minimal calorie foods or beverages are allowed, such as water, seltzer, black coffee or tea. Protein shakes, alcohol, and other calorie-containing beverages are typically not allowed during fasting times, in order to keep the body in the “rest and digest” mode to repair itself.
Who is 16:8 Best For?
As a registered dietitian, I’ve seen the 16:8 approach work best for those who may already delay breakfast, enjoy structured meal timing, and don’t have specific medical conditions or disordered eating habits in which rules around meal times can cause stress.
It also may be a good method for someone who likes to be social, as it offers a longer window of time for eating than some other fasting methods, making it easier to enjoy eating out in the evening.
16:8 Fasting Results 1 Month
After four weeks of 16:8 fasting, here are a few things you may notice:
- Improved energy
- More stable blood sugar levels
- Better digestion
- Weight loss
Many factors can influence your results, including genetic/biological responses, diet quality, overall protein intake, sleep stress, and activity level. The Fasting App by Municorn enables you to track your fasting schedule, results, and individual responses so you can see your progress and make tweaks along the way.
Many people consider intermittent fasting as a weight loss tool that doesn’t require calorie-counting. If this sounds appealing to you, the next section shares typical intermittent fasting 1 month results for weight loss.
Fasting Weight Loss Timeline: Weeks 1-4
Within your first four weeks of 16:8 fasting, there are several metabolic changes you may start to see. While everyone’s weight loss journey will look a bit different and evolves at its own unique pace, there are a few general things I tell my clients to expect.
Week 1: The Adjustment Phase
Hunger fluctuations and cravings may surface
Hunger may fluctuate and more intense cravings may come up during the first week of 16:8 fasting. This is normal and to be expected as your hormones begin to adapt to the changes in your eating schedule. Your body gets used to your typical schedule and eating habits, and it just needs a bit of time to adjust to a new routine.
Headaches, fatigue, or irritability
As your body adjusts to your new fasting schedule, you may also notice headaches, fatigue, or irritability, especially during fasting windows. Some of these symptoms are associated with the “keto flu,” a cluster of symptoms derived from the keto diet that may come up during the initial phases of fasting. A lot of these symptoms are thought to be related to electrolyte and fluid losses in the early stages of fasting.
Scale changes driven by water weight
You may see the scale dip down (although do not stress if this doesn’t happen right away). Most of the weight loss seen in the first week will be “water weight”, not fat loss.
This is well-documented in fasting research and is a result of sodium excretion, which pulls water with it, and increased urination due to reduced insulin levels. This decrease in insulin is a good thing not only as a driver of that initial weight loss, but because the body doesn’t have to work as hard to remove glucose (e.g., sugar) out of the blood.
Expert Tips for Week 1
Prioritize hydration and electrolytes to replace losses, eat enough protein and fiber at meals to curb hunger, and avoid under-eating to reduce symptoms.
Week 2: Adaptation Begins
Hunger becomes more predictable
While there are not many research studies that specifically measure hunger week-to-week, many people report their hunger starting to stabilize and feel more in control after the first week of a 16-hour fast. This doesn’t mean you won’t feel hungry at all, itm’s just that it can become more predictable as your hunger hormones start to anticipate when it’s time to eat in your new schedule.
Energy levels stabilize
Many people report more stable energy as blood sugar becomes more regulated. Ketones are also produced from the burning of fat when glycogen (e.g., the storage form of carbohydrate) stores are low, which can improve the body’s energy efficiency.
Early fat loss vs water loss
You may notice the scale continues to drop, which could be remaining water loss from the first week or the early stages of fat loss. While intermittent fasting methods like 16:8 don’t require a calorie restriction, many people naturally reduce their calorie intake simply by narrowing their eating window.
Improved meal structure and awareness
After a few weeks of a consistent 16:8 schedule, you may notice an improvement in your meal structure and fewer unplanned snacks. This can make it easier to 16:8 into a routine that your body learns to expect.
Expert Tips for Week 2
Try to maintain as much consistency in your fasting schedule as possible so your body and brain know what to expect. There is certainly room for flexibility as you progress further along your fasting journey, but it can be helpful to be more consistent in the early weeks.
Week 3: Metabolic & Appetite Shifts
Better appetite control
Appetite regulation may continue to improve as your insulin sensitivity and hunger hormones stabilize. Most people notice this starting to occur by weeks 3 or 4, and can serve as a sign your body is getting used to your new way of eating.
Fewer cravings and snacking urges
Consistent meal timing over a longer duration may reduce unwanted cravings and mindless snacking as your brain and body feel more satisfied. This is especially true if protein and fiber targets are met, which are the two most satiating (e.g., satisfying) nutrients.
Possible non-scale wins
Week three is when non-scale wins become more apparent. You may see improvements in quality of life measures such as sleep duration and quality, better digestion, and less bloating. Some of my clients also report increased focus and memory, which may be attributed to its benefits on the gut, which is closely connected to brain health.
Weight loss pace may slow
The rate of weight loss may slow down as your water weight stabilizes, but this doesn’t mean fat loss has permanently stalled. When embarking on a weight loss journey with any method, there is often an initial larger water weight loss in the beginning and then a temporary slowdown as the body readjusts to its new routine.
Knowing this possibility can be helpful if this does occur, so you know it’s only temporary.
Expert Tips for Week 3
Continue tracking your weight, but also pay attention to non-scale wins like increased energy or focus, to keep your motivation up.
Week 4: Momentum & Sustainability
More “real” results aside from weight loss
At four weeks, you’ll notice more meaningful changes and not just temporary shifts. Research shows benefits start to show up for insulin resistance, focus and memory, energy, digestive health, blood pressure, and more when intermittent fasting over longer periods of time.
Body composition changes
Improvements in body composition and measurements can occur, such as body fat reduction or muscle mass increasing simultaneously, even if the number on the scale plateaus temporarily.
Expert Tips for Week 4
Take some time to reflect on the last four weeks, making note of what went well, what was challenging, and how you’d like to approach moving forward. Did 16:8 overall work well for you, and your body adjusted after a week or two, or did it feel hard the whole time? Exploring this can help you determine if 16:8 is a good plan for you in the long term.
Typical 16:8 Fasting Weight Loss Results 1 Month
If weight loss is a goal, here’s a typical fasting weight loss timeline you may expect in the first month on 16:8. Again, this timeline is a typical average, and will look a bit different for everyone.
After 1 month of 16:8 fasting, weight loss is generally modest, ranging from 2-5% of body weight. This amount of weight loss can vary depending on your overall calorie intake, physical activity level, stress level, sleep quality, and other individual characteristics.
In my practice, I’ve found those who previously were “grazers,” consumed a larger amount of calories, or who ate frequently over long periods of time are more often the ones who lose the most weight in the beginning. This is likely because it is more of a drastic change for them, compared to someone who normally may be consuming a similar amount of calories than they would when switching to an 8-hour window.
As mentioned before, however, weight loss plateaus can still occur in the first month after the initial water weight is lost and weight stabilizes. This doesn’t mean 16:8 is not working for you, it’s just that true fat loss can take a bit longer to occur.
The best weight loss success comes from combining 16:8 fasting with a moderate calorie deficit, adequate protein intake, and consistent physical activity.
Remember the importance of focusing on your own journey, rather than comparing yourself to others. The Fasting App helps you track your own journey, so you can build habits that work for you.
Benefits of a 16:8 Fast
The 16:8 method may be easier to follow than more restrictive methods like 18:6 or one-meal-a-day (OMAD), and offers several benefits.
Calorie awareness without strict tracking
Research shows that 16:8 fasting methods reduce overall calorie intake without the need for strict calorie tracking. For example, evidence shows intermittent fasting methods like 16:8 may reduce calorie intake by 20-30%, likely as a result of a narrowed eating window where the amount of food you eat in a given day naturally declines.
Improved insulin sensitivity
An analysis of eight controlled studies found that 16:8 fasting was associated with improved insulin-sensitivity markers, including a decrease in HOMA-IR, a marker of insulin resistance that would be high in those with diabetes or poor blood sugar control.
Fat burning and metabolic health
A 2024 study showed that just three days per week of 16:8 fasting led to weight loss and better metabolic health, including better glucose and lipid profiles.
Better appetite regulation
Fasting protocols are associated with decreased levels of the hunger hormone ghrelin,which can support better appetite control. And even though the window of time to eat is shorter, fasting doesn’t appear to increase the drive to eat that is often seen with daily calorie restriction.
Other potential benefits
While research is still emerging, intermittent fasting may have benefits for digestion, cognition, and overall energy levels.
Lifestyle flexibility
16:8 fasts tend to fit easier into daily life than longer fasting protocols. This is primarily because you don’t have to account for full days without food like in traditional alternate-day fasting or squeeze all your calories into one meal like OMAD.
How to Do 16:8 Fasting the Right Way
Get on a meal schedule
Going too long without eating or not following a schedule can also make it harder to get in the nutrients you need in a shorter window. Adopting a regular, consistent meal schedule on a 16:8 plan tells your body what to expect and can reduce hunger. In my practice, I often provide a suggested meal schedule for clients as a guide, which many find helpful as a reminder to not skip meals.
Prioritize nutrition quality
To get the best results from 16:8 fasting and for overall health benefits, it’s essential to prioritize nutrition quality during your eating windows. This means choosing nutrient-dense foods like fruits, vegetables, lean proteins, whole grains, and healthy fats to meet your nutritional needs.
Emphasize protein, fiber, and hydration
Eating a diet rich in protein and fiber helps to balance blood sugar, boost energy, and control hunger during fasting times. Staying hydrated is another component to prevent fatigue and headaches, especially during fasting windows.
Strength train and move regularly
Including strength training in your routine will help preserve muscle mass and aid in weight loss. Daily low-intensity movement, such as frequent walking, should also be prioritized.
Avoid other common mistakes
Being too restrictive in your diet or getting poor sleep can put stress on the body and reduce fasting benefits. In addition, inadequate protein intake without enough strength training can put you at risk for muscle loss, which can lead to weakness.
If you’re doing all these things and are still low on energy, are very hungry, or have impaired performance after the first month, you may want to consider adjusting or shortening your fasting window.
Who Should Be Cautious or Avoid 16:8 Fasting
Certain people should be cautious or avoid 16:8 fasting, such as those:
- Diagnosed with diabetes and blood sugar disorders
- Taking medications requiring food
- Are pregnant or breastfeeding
- Have an eating disorder history
Make sure to always consult with a physician before starting an intermittent fasting plan, especially if any of these situations applies to you.
Is 16:8 Worth Continuing After 1 Month?
Here are a few things to consider in your decision-making process.
Signs it’s working for you
16:8 may be a good fit if you notice benefits in the first month and adapt quickly, without feeling too much stress or negative changes in your relationship with food.
Signs it may need modification
If you’re experiencing intense fatigue, continuous hunger, irritability, poor sleep, or decreased performance, you may want to modify your fasting schedule.
How to transition to maintenance or flexibility
You can loosen the rigidity of your structure by only doing 16:8 on certain days of the week or shortening your fast. In this case, you can think of 16:8 as a flexible tool to follow on most days rather than a non-negotiable rule that you follow no matter what.
Key Takeaways
Knowing what to expect after 1 month of fasting can help you better prepare for your journey. Rather than rushing the process in the first four weeks, it’s helpful to focus on consistency, nutrition quality, and flexibility for long-term success.
The Fasting App makes this process easier by helping you track your fasting schedule, notice patterns in hunger and energy, and personalize your approach over time. In this way, fasting becomes a supportive framework, not a rigid rule.
