Fasting Until 4pm: Pros, Cons, And How To

Fasting until 4pm, often called a form of time-restricted eating, is one way that people can:

• Support health
• Manage weight
• Align eating habits with personal routines (1). 

But like any health practice, it comes with nuances worth exploring before jumping in.

This guide will walk you through the ins and outs of fasting until 4pm.

Together, we’ll unpack the science behind this eating style, covering:

• The possible benefits of fasting until 4pm
• The challenges you might face
• How to make it sustainable

We’ll also discuss some key considerations to remember because, like anything health-related, what works for one person may not work for another.

Is It Safe To Fast Until 4PM?

Safety is one of many people’s first questions about fasting until 4pm, and it’s a valid concern. Fasting can be safe for most healthy adults if done mindfully and with good preparation.

However, if you’re asking, “What is a healthy way to do fasting until 4pm?”

You must consider certain factors to ensure the practice supports your health rather than working against it.

Fasting until 4pm typically involves going without food for much of the day. 

Food abstinence means your body relies on stored energy, primarily glucose and fat, to fuel your activities. 

Using stored energy is a normal metabolic process for the average adult and doesn’t usually pose harm (2). However, your body’s response to the process can vary depending on your health status, lifestyle, and individual needs.

For healthy individuals, mild hunger, lightheadedness, or fatigue are common during initial attempts at fasting (3). These are often temporary as the body adjusts to this new eating schedule. Staying hydrated during the fasting period is essential. 

While you may skip meals, water, herbal teas, and other non-caloric fluids are crucial to maintaining normal body functions.

Fasting until 4pm can pose risks for some groups (4):

• People with diabetes, especially those on medications that lower blood sugar, are at higher risk of hypoglycemia (low blood sugar).
• Pregnant or breastfeeding individuals need regular and adequate nutrition, so experts do not recommend fasting here.
• Doctors advise against children, teens, older adults, and anyone underweight trying prolonged fasting due to their higher nutritional demands.
• For those with other medical conditions, such as heart problems or eating disorders, it’s best to consult with a healthcare provider before trying this approach.
• Even for generally healthy people, making any drastic dietary change without guidance can sometimes lead to unintended consequences.

Another important safety factor is how you break the fast after 4pm. 

Overeating or choosing nutrient-poor, calorie-heavy foods can defeat any potential benefits. Easing into your first meal with a balanced, nutrient-dense option is key to supporting digestion and maintaining energy levels (5).

Ultimately, the safety of fasting until 4pm depends on your health and how well you listen to your body. If you feel dizzy, extremely weak, or unwell, it’s a sign that this fasting pattern may not be suitable for you. Always prioritize your well-being and seek advice from a trusted healthcare professional if you’re unsure.

Done thoughtfully, fasting can be a part of a healthy routine for some. 

Just be sure to approach it with attention to your body’s needs and personal circumstances.

What Are The Benefits Of Fasting Until 4PM?

Fasting until 4pm can offer several potential health benefits. These benefits largely depend on your diet, lifestyle, and health status. 

Here is a breakdown of the key benefits of fasting until 4pm:

1. Supports Weight Management

Fasting creates a natural calorie deficit. By limiting the window of time you eat, you might consume fewer calories overall. 

Studies suggest that time-restricted eating patterns, like fasting until 4pm and others, can aid weight loss when paired with balanced meals (6). The body also shifts to using stored fat for energy during fasting periods, which may help with fat loss over time.

2. Improved Blood Sugar Control

Fasting may improve how your body handles blood sugar. Research suggests that structured fasting periods may enhance insulin sensitivity (7). Insulin is the hormone that helps regulate blood sugar levels (8).

When your body becomes more sensitive to insulin, it uses blood sugar more effectively (9). This sensitivity might lower your insulin resistance risk, a precursor to type 2 diabetes.

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3. Enhanced Metabolic Flexibility

Metabolic flexibility is your body’s ability to switch between burning carbohydrates and fats for energy (10).

Fasting until 4pm allows your body to tap into fat stores when glucose (sugar) from food isn’t available (11). Over time, this adaptability may support better metabolic health, although more research is needed to understand how this works (12).

4. Promotes Digestive Health

Giving your digestive system a prolonged break might be helpful for some people. 

It allows the gut to rest and repair. 

Some studies hint that fasting may improve gut health by supporting healthy bacteria (13). However, breaking your fast with fiber-rich and nutrient-dense foods is essential to maximize benefits.

5. Encourages Mindful Eating

With limited eating hours, many people become more intentional about how and what they eat. Knowing your meals need to nourish you after a fast often leads to better food choices like whole grains, lean proteins, and fresh produce. Over time, this can foster healthier eating habits.

6. Potential Longevity Benefits

While there is ongoing research, early studies suggest fasting may activate specific cellular repair processes, such as autophagy (14, 15).

Autophagy is the body’s way of cleaning out damaged cells to make way for healthier ones (16). 

Experts have linked this process to improved longevity and reduced risks of age-related diseases, though much of this evidence comes from animal studies (17).

7. May Boost Mental Clarity

Many individuals report feeling sharper and more focused while fasting. This mental improvement could be due to stabilized blood sugar levels and the body’s production of ketones, an alternative fuel source for the brain during fasting. 

While this is mainly anecdotal, some studies support that fasting may benefit brain health, although more research is needed (18, 19).

8. Simplifies Your Routine

By skipping meals until 4pm, you spend less time planning and preparing food during the day (basically morning fasting, then afternoon fasting). This simplicity might free up mental energy and time, making daily routines less stressful for some.

Remember, no one can guarantee these benefits for everyone. 

Individual experiences can vary. Consistency, balance, and listening to your body are key to making fasting work for you. Always pair fasting with a nutrient-rich diet to safely and effectively enjoy its potential advantages.

Read more: 12-Hour Fast Vs. 16-Hour Fast: Which Of These Two Dietary Patterns Is Better?

Are There Side Effects To Fasting Until 4PM?

Fasting until 4pm can have some side effects (20), especially if you’re new to this eating pattern or don’t approach it mindfully. Below, we outlined several potential side effects, broken into key areas for clarity.

1. Hunger And Irritability (The “Hangry” Effect)

Hunger can happen when skipping breakfast, lunch, and snacks until 4pm. 

For some people, this can lead to irritability or mood swings, often called feeling “hangry.” 

The body releases stress hormones like cortisol when you haven’t eaten for a while, which might amplify feelings of frustration or anxiety. 

These effects often lessen as your body adjusts to the fasting routine, making the idea that breakfast is the most important meal of the day a myth.

2. Low Energy Levels

Without food during the day, your energy might dip. 

You could feel sluggish or find concentrating more of a challenge, especially during the first few days of fasting. This happens because the body is transitioning from relying on glucose (sugar) from meals to using stored fat for fuel, a process called ketosis (21).

Staying hydrated can help counteract some of this fatigue.

3. Headaches

Headaches are a common complaint among those who fast. 

They can result from dehydration, caffeine withdrawal (if you cut back on coffee), or fluctuations in blood sugar levels. Drinking plenty of water and maintaining your usual intake of non-caloric beverages, like tea or black coffee, may reduce the likelihood of headaches. Talk to your healthcare provider if your symptoms are severe or don’t go away.

4. Digestive Discomfort

Some people experience bloating, constipation, or other digestive issues during fasting. 

Skipping meals can slow digestion in some instances. When breaking your fast after 4pm, consuming high-fiber foods and staying hydrated can support smoother digestion and minimize discomfort.

5. Risk Of Overeating

Prolonged fasting can sometimes lead to overeating when the fasting window ends.

This urge to overeat happens because your body and brain are signaling for quick energy. If careless, you may gravitate toward calorie-dense, less nutritious food choices. 

This choice can undo some of the potential benefits of fasting. Planning balanced meals with protein, fats, and carbohydrates can help you avoid this pitfall.

6. Dizziness Or Lightheadedness

Going too long without food, especially with dehydration, can cause dizziness or lightheadedness. This effect is more likely if your fasting schedule doesn’t align with a nutrient-rich diet. Eating enough during your eating window and replenishing fluids is critical to prevent this symptom. 

If symptoms interfere with your ability to accomplish what you need during the day, then maybe this fasting schedule isn’t the right fit for you, and that’s okay. 

If fasting until 4pm doesn’t work, many other options exist, such as alternate day fasting schedules.

7. Lower Physical Performance

Fasting until 4pm may have an impact on physical activity. 

Without readily available energy from meals, your performance in high-intensity or endurance exercises could drop. Lower performance is essential for athletes or those with demanding fitness routines to consider. Timing your workouts strategically, such as after breaking your fast, can help mitigate this.

8. Potential Nutrient Deficiencies

With limited eating hours, it’s easy to miss the mark on essential nutrients like vitamins, minerals, and fiber. Deficiencies can develop over time if meals during the eating window aren’t balanced and nutrient-dense. Meal planning and including a variety of whole foods are crucial to avoid nutritional gaps.

9. Dehydration

Fasting doesn’t mean skipping fluids, but sometimes, people unintentionally drink less when focused solely on not eating. This lower intake can lead to mild dehydration, presenting symptoms like a dry mouth, fatigue, or darker urine. Make hydration a priority throughout the day, even when fasting.

Fasting until 4pm has potential benefits, but it’s essential to be mindful of these side effects. 

Many fasting side effects are temporary, and you can minimize them by:

• Staying hydrated
• Eating balanced meals
• Listening to your body

If symptoms feel extreme or persist, fasting may not be the right choice for you. 

Always consult a healthcare professional if unsure about its suitability for your unique health needs.

Read more: The Ultimate Fasting Mimicking Diet Food List For Beginners

Who Should Avoid Fasting Until 4PM And Why?

Fasting until 4pm isn’t for everyone. While some may thrive on this eating schedule, it can pose risks for particular groups (4, 22).

• Pregnant And Breastfeeding Individuals

The body requires extra calories and nutrients during pregnancy and breastfeeding to support the baby’s development and milk production. 

Prolonged fasting can lead to nutrient deficiencies and lower energy, which may affect both parent and baby. Consistent, balanced meals are critical during these life stages.

• Individuals With Diabetes Or Blood Sugar Disorders

People with diabetes, especially those on medication or insulin, are at higher risk of hypoglycemia (low blood sugar) when fasting. Skipping meals until late in the day can also cause wild fluctuations in blood sugar levels. These unstable blood sugar fluctuations can be dangerous and hard to manage without close monitoring by a healthcare provider.

• Those With A History Of Eating Disorders

Time-restricted eating patterns like fasting could trigger unhealthy behaviors or thoughts in people with a history of eating disorders, such as anorexia or binge eating disorder. Structured meal patterns and focusing on balanced nutrition are typically safer options for long-term health in this population.

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• Children And Teenagers

Growing children and teens have higher nutrient and energy demands. 

Fasting until 4pm can interfere with these needs and impact their growth, development, and ability to concentrate, especially during school hours. Regular, nutrient-rich meals are essential for this age group.

• Underweight Or Malnourished Individuals

Fasting periods limit eating opportunities, making it harder for those underweight to meet their daily calorie and nutrient requirements. The limited eating period can worsen malnutrition or lead to unintended weight loss, affecting energy levels and overall health.

• Individuals With Chronic Medical Conditions

Chronic illnesses such as heart disease, kidney disease, or severe gastrointestinal issues may make fasting risky. For example, fasting could exacerbate specific symptoms like fatigue or digestive discomfort. Specialized dietary plans tailored to the condition are often a better choice.

• Athletes Or Highly Active Individuals

Athletes and those engaged in physically demanding work may struggle to fuel their performance with a fasting schedule like this. Energy and protein needs are typically higher, and prolonged fasting periods can hinder recovery and muscle repair. 

Eating strategically throughout the day is more appropriate for this group.

• Anyone Taking Medications With Food Requirements

Certain medications require food for proper absorption or to reduce side effects like stomach irritation. 

Fasting until 4pm might interfere with prescribed medication timing and its effectiveness. 

Always check with a healthcare provider before adjusting your eating schedule. 

Even some common over-the-counter medications, like ibuprofen, need to be taken with food or at least not on an empty stomach, which is something to keep in mind.

• Those Who Experience Chronic Fatigue

People prone to low energy levels or chronic fatigue may find fasting worsens symptoms. Without regular energy intake, it can be hard to power through daily tasks, leading to an unproductive and miserable day.

• Elderly Individuals

Older adults often have unique nutritional needs and may be more vulnerable to the risks of prolonged fasting, such as dehydration and nutrient deficiencies. 

They may also have coexisting health conditions, making regular, balanced meals more beneficial.

Fasting until 4pm can work well for some, but it’s not a one-size-fits-all approach. 

The groups mentioned above should prioritize balanced, consistent eating patterns that meet their unique needs. If you’re considering fasting and fall into one of these categories, it’s best to consult a healthcare provider first. Your health and safety should always come first.

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How Does Fasting Until 4PM Impact Weight Loss?

Fasting until 4pm has become a popular weight loss strategy, but how does it work? 

Let’s break down the science behind its effects on weight loss and body composition.

• Fewer Calories Consumed Overall

Fasting until 4pm limits your eating window, which can naturally reduce the number of daily calories you consume. With fewer opportunities to snack or eat large meals throughout the day, it becomes easier to create a calorie deficit. 

A calorie deficit, when you burn more calories than you take in, is the key to weight loss (23).

• Promotes Fat Burning

During extended fasting periods, your body taps into its energy reserves, including stored fat, to function. This fat storage usage happens when glucose (sugar) from recent meals is no longer available. Breaking down fat for energy is called lipolysis (24).

Over time, this could help reduce fat stores and support weight loss, but you still need a calorie deficit (25).

• Reduces Insulin Levels

Fasting periods can lead to lower insulin levels in your body. Insulin is a hormone that helps store excess glucose as fat. Some researchers say when insulin levels drop, your body burns stored fat more efficiently. Improved insulin sensitivity (your cells’ response to insulin) may also help improve metabolic health over the long term (26).

• Minimizes Mindless Eating

A structured eating timeframe can help prevent mindless snacking, which often adds extra calories. Knowing you have a set eating period may make you more intentional about your food choices, reducing the chances of overeating or indulging in less nutrient-dense options.

• May Enhance Appetite Regulation

Studies suggest that intermittent fasting until 4pm and other related eating patterns may help regulate hunger hormones such as ghrelin (which signals hunger) and leptin (which signals fullness), at least in comparison to more traditional calorie-restriction diets (27). 

By aligning these hormones, fasting might help you feel fuller after meals, reducing overeating during your eating period.

• Influences Metabolism

Fasting may temporarily boost metabolism by increasing norepinephrine, a hormone that stimulates fat breakdown (28). However, this effect might diminish if fasting decreases calorie intake over time, as the body might adapt by lowering its metabolic rate.

• Supports Long-Term Behavioral Changes

Fasting until 4pm simplifies your daily routine and eating habits, which, for some people, may aid in long-term weight management. By focusing on nutrient-dense, satisfying meals during your eating window, you establish better eating patterns that support a healthier body weight over time.

• P/S – Individual Responses To Fasting Vary

Not everyone will experience the same degree of weight loss. Genetics, activity levels, and overall diet quality play crucial roles. Fasting alone isn’t a magic solution. 

Sustainable weight loss requires a consistent calorie deficit, balanced nutrition, and physical activity.

It’s worth noting that weight loss through fasting is most effective when your eating window includes wholesome, nutrient-rich foods. Filling up on ultra-processed or calorie-dense foods after fasting can offset potential progress. Moderation and balance are key for making fasting a helpful tool in your weight loss journey.

If you’re considering fasting until 4pm to lose weight, evaluate your eating habits and health needs. It can be a helpful strategy, but it works best when you pair it with mindful eating and lifestyle changes.

Frequently Asked Questions

• Does coffee break a fast?

Black coffee does not break a fast as it contains almost no calories and does not significantly impact insulin levels. However, adding cream, sugar, or flavored syrups would break your fast.

• What happens after 1 month of intermittent fasting?

After 1 month of intermittent fasting, you may notice improved blood sugar control, potential weight loss, and better appetite regulation (2). Individual results vary based on diet, lifestyle, and health status.

• Does fasting burn belly fat?

Fasting can promote fat burning, including belly fat, by creating a calorie deficit and encouraging using stored fat for energy. However, targeted fat loss is not guaranteed, as genetics also affect fat distribution.

• Does sleeping count as fasting?

Yes, sleeping counts as fasting because you’re not consuming any calories during that time. It’s often considered part of the fasting window in intermittent fasting schedules.

The Bottom Line

Fasting until 4pm can be a safe and effective practice for some people, but it’s not suited to everyone. It may offer benefits like weight loss, improved fat burning, and better appetite regulation. However, it can have drawbacks like low energy, headaches, or nutrient deficiencies if not done correctly. Certain groups, including children, pregnant individuals, and those with medical conditions, should avoid it altogether.

If you’re considering this fasting method, listen to your body and focus on nutrient-rich meals during your eating window. Always consult a healthcare provider to ensure it’s a safe option for you.