Understanding Intermittent Fasting: How It Works and Its Benefits

Intermittent fasting alternates between fasting and eating periods, promoting fat burning and offering health benefits such as weight loss, improved brain health, and reduced diabetes risk. However, it may not be suitable for everyone and should be approached with caution and proper nutrition.

Intermittent fasting is a dietary approach that alternates between periods of fasting and eating. This method aims to systematically starve the body long enough to trigger fat burning. While research is ongoing, evidence suggests that when practiced correctly, intermittent fasting can lead to weight loss, lower blood pressure and cholesterol levels, better diabetes management, and enhanced brain health.

## The Science Behind Intermittent Fasting

During a meal, carbohydrates are broken down into glucose, which is absorbed through the intestinal wall into the bloodstream. Glucose serves as the primary energy source for various organs. Any excess glucose is stored in the liver and adipose tissue as glycogen and fats.

### Energy Use During Fasting

In the fasted state, the liver converts glycogen back into glucose to maintain energy levels. An inactive person typically depletes glycogen stores within 10 to 12 hours, while someone who exercises may do so more quickly. Once glycogen reserves are exhausted, the body begins to utilize energy stored in adipose tissues. At this point, fats are broken down into free fatty acids, which are then converted into additional metabolic fuel in the liver. If fasting continues long enough, the body will burn fat for energy, leading to fat loss and associated health benefits.

## The Role of Insulin

Insulin is a hormone essential for transporting glucose into cells. Its levels fluctuate, being high after meals and low between them. Frequent eating keeps insulin levels elevated, which can lead to insulin insensitivity—a precursor to prediabetes and type 2 diabetes. Intermittent fasting helps maintain lower insulin levels, thereby reducing the risk of diabetes.

### Benefits for Brain Health

Fasting also positively impacts brain health. It challenges the brain similarly to physical or cognitive exercises, promoting the production of neurotrophic factors that support neuron growth and survival. This can enhance cognitive function and overall brain health.

## Who Should Avoid Intermittent Fasting?

Despite its benefits, intermittent fasting is not suitable for everyone. Certain groups should avoid this dietary approach, including:

- Children and teenagers

- Pregnant or breastfeeding women

- Individuals with eating disorders or type 1 diabetes

- Those with advanced diabetes or other serious medical conditions

- People who are underweight or frail

Fasting can also pose risks if not done correctly or if overdone.

## Approaches to Intermittent Fasting

There are various methods of intermittent fasting, but one of the simplest is extending the usual nighttime fast. A common approach is a daily cycle of 16 hours of fasting followed by an 8-hour eating window. This method is often sustainable for many individuals.

### Best Practices for Safe Intermittent Fasting

To ensure that intermittent fasting is both safe and effective, it should be paired with balanced meals that provide adequate nutrition. Staying hydrated is crucial, and individuals should be aware of their physical limits while fasting. It is also important to break the fast gradually and avoid overeating, particularly unhealthy foods, after fasting periods.

## Conclusion

Intermittent fasting can be a powerful tool for weight management and improving overall health when done correctly. However, it is essential to approach it with caution, ensuring that it aligns with individual health needs and lifestyle. By understanding how intermittent fasting works and its potential benefits, individuals can make informed decisions about whether this dietary approach is right for them.

Six methods of intermittent fasting

There are various methods of intermittent fasting, and people will prefer different styles. Read on to find out about six different ways to do intermittent fasting.

1. Fasting for 12 hours a day

The rules for this diet are simple. A person needs to decide on and adhere to a 12-hour fasting window every day.

According to some researchers, fasting for 12 to 14 hours can causeTrusted Source the body to turn its fat stores into energy, which releases ketones into the bloodstream. This shouldTrusted Source encourage weight loss.

This type of intermittent fasting plan may be a suitable option for beginners. This is because the fasting window is relatively small, much of the fasting occurs during sleep, and the person can consume the same number of calories each day.

The easiest way to follow the 12-hour fast is to include the period of sleep in the fasting window.

For example, a person could choose to fast between 7 p.m. and 7 a.m. They would need to finish their evening meal before 7 p.m. and wait until 7 a.m. to eat breakfast but would be asleep for much of the time in between.

2. Fasting for 16 hours

Fasting for 16 hours a day, leaving an 8-hour eating window, is called the 16:8 method or the Leangains diet.

Some experts may recommend females fast for 14 hours and slowly build their way up to 16 hours, while males can start fasting for 16 hours straight away.

This type of intermittent fast may be helpful for someone who has already tried the 12-hour fast but did not experience any benefits.

On this fast, people usually finish their evening meal by 8 p.m. and skip breakfast the next day, not eating again until noon.

A 2022 review Trusted Source found that this fasting method, alongside calorie restriction, may be beneficial for weight management in adults with overweight or obesity and may have a positive effect on blood sugar processing.

3. Fasting for 2 days a week

People following the 5:2 diet eat standard amounts of healthful food for 5 days and reduce calorie intake on the other 2 days.

During the 2 fasting days, men generally consume 600 caloriesTrusted Source and women 500 calories.

Typically, people separate their fasting days in the week. For example, they may fast on a Monday and Thursday and eat regularly on the other days. There should be at least 1 nonfasting day between fasting days.

There is limited research on the 5:2 diet, which is also known as the Fast diet.

A 2022 studyTrusted Source examining different types of fasting found that the 5:2 diet had no clear ranking when compared with the other intermittent fasting regimens.

A 2021 randomized controlled trialTrusted Source found that adults with obesity who tried the 5:2 fasting method with group support experienced a greater weight loss at 6 weeks and rated the diet highly.

However, the effect of weight loss diminished over time, with the weight difference no longer being significant by 1 year.

4. Alternate day fasting

There are several variations of the alternate day fasting plan, which involves fasting every other day.

For some people, alternate day fasting means a complete avoidance of solid foods on fasting days, while other people allow up to 500 calories. On feeding days, people often choose to eat as much as they want.

Alternate day fasting is an extreme form of intermittent fasting, and it may not be suitable for beginners or those with certain medical conditions. It may also be difficult to maintain this type of fasting in the long term.

5. A weekly 24-hour fast

Fasting completely for 1 or 2 days a week, known as the Eat-Stop-Eat diet, involves eating no food for 24 hours at a time. Many people fast from breakfast to breakfast or lunch to lunch.

People following this diet plan can have water, tea, and other calorie-free drinks during the fasting period.

People should return to regular eating patterns on non fasting days. Eating in this way reduces a person’s total calorie intake but does not limit the specific foods the individual consumes.

A 24-hour fast can be challenging and may cause fatigue, headaches, or irritability. Many people find these effects become less extreme over time as their bodies adjust to this new eating pattern.

People may benefit from trying a 12-hour or 16-hour fast before transitioning to the 24-hour fast.

6. The Warrior Diet

The Warrior Diet is a relatively extreme form of intermittent fasting.

It involves eating very little, usually just a few servings of raw fruit and vegetables, during a 20-hourTrusted Source fasting window, then eating one large meal at night. The eating window is usually only around 4 hours.

This form of fasting may be best for people who have tried other forms of intermittent fasting already.

Supporters of the Warrior Diet claim that humans are natural nocturnal eaters and that eating at night allows the body to gain nutrients in line with its circadian rhythms.

During the 4-hour eating phase, people should make sure they consume plenty of vegetables, proteins, and healthy fats. They should also include some carbohydrates.

Although it is possible to eat some foods during the fasting period, it can be challenging to stick to strict guidelines on when and what to eat in the long term. Some people may also have difficulty eating such a large meal so close to bedtime.

There is also a risk that people on this diet will not eat enough nutrients, such as fiber. This can increase the risk of cancer and have an adverse effect on digestive and immune health.

Other tips for intermittent fasting

It can be challenging to stick to an intermittent fasting program.

The following tips may help people stay on track and maximize the benefits of intermittent fasting:

• Staying hydrated: Drink lots of water and calorie-free drinks, such as herbal teas, throughout the day. This can help ensure you get enough electrolytes, sodium, and potassium chloride.
• Avoiding thinking about food: Plan plenty of distractions on fasting days to avoid thinking about food, such as catching up on paperwork or going to see a movie.
• Resting and relaxing: Avoid strenuous activities on fasting days, although light exercise such as yoga may be beneficial.
• Making every calorie count: If the chosen plan allows some calories during fasting periods, select nutrient-dense foods that are rich in protein, fiber, and healthful fats. Examples include beans, lentils, eggs, fish, nuts, avocado, and unprocessed meats.
• Eating high volume foods: Select filling yet low calorie foods, which include popcorn, raw vegetables, and fruits with high water content, such as grapes and melon.
• Increasing the taste without the calories: Season meals generously with garlic, herbs, spices, or vinegar. These foods are extremely low in calories yet are full of flavor.
• Choosing nutrient-dense foods after the fasting period: Eating foods that are high in fiber, vitamins, minerals, and other nutrients helps to keep blood sugar levels steady and prevent nutrient deficiencies. A balanced diet will also contribute to weight loss and overall health.

Fiber-rich foods

Fiber-rich foods are essential for maintaining good digestive health, aiding in weight management, and potentially reducing the risk of several chronic diseases. Here's a list of foods that are high in fiber:

Fruits:

• Apples: Especially with the skin on.
• Berries (like raspberries, blackberries, and blueberries).
• Pears: Preferably with the skin.
• Oranges and other citrus fruits.
• Avocados.

Vegetables:

• Leafy Greens: Spinach, kale, Swiss chard.
• Broccoli, Brussels sprouts, and cauliflower.
• Carrots, particularly when eaten with the skin.
• Sweet Potatoes and regular potatoes with skin.
• Legumes: Beans (black, kidney, pinto), lentils, chickpeas, and peas.

Whole Grains:

• Oats: Oatmeal or oat bran.
• Barley.
• Quinoa.
• Whole Wheat: Bread, pasta, or products made with whole wheat flour.
• Brown Rice.
• Bulgur.

Nuts and Seeds:

• Almonds, walnuts, and other nuts.
• Chia Seeds, flaxseeds, and pumpkin seeds.

Other:

• Popcorn: When air-popped, it's a whole grain.
• Bran Cereals or products where bran is added.

Tips for Increasing Fiber Intake:

• Gradual Increase: Suddenly upping your fiber intake can cause digestive discomfort. Gradually increase your fiber consumption to allow your body to adjust.
• Balance with Water: Fiber works best when you're well-hydrated. Drink plenty of water to help fiber move through your digestive system.
• Mix It Up: Don't rely on just one source; vary your intake from different food groups to get a range of nutrients along with fiber.
• Read Labels: When buying packaged foods, check the fiber content. Look for products where fiber is listed high on the nutrition facts.
• Snack Smart: Choose snacks like fresh fruits, veggies with hummus, or nuts instead of processed snacks.
• Cook with Fiber: Incorporate beans or lentils in soups, stews, or salads. Use whole grains in place of refined grains in cooking.

Remember, while increasing fiber intake can have numerous health benefits, it's important to do so in a balanced manner to avoid potential side effects like bloating or gas. If you're making significant changes to your diet, consider consulting with a nutritionist or dietitian for personalized advice.