Last Updated on: 18 Sep 2026
Intermittent fasting is a type of eating plan which is based on scheduled and regular switching between fasting and eating. According to research, you can control your weight and possibly even reverse some types of disease by doing intermittent fasting. Now the questions arise, What should be the method? Is it safe as well?
Obesity is a serious health issue that can result in additional serious risks like digestive disorders like fatty liver and metabolic diseases like type 2 diabetes, high blood pressure, and stroke. The World Health Organisation reports that the percentage of adults aged 18 and over who are overweight or obese has nearly tripled from 1975 to 2016 (13% and 39%, respectively). Globally, preventable obesity is still regarded as a serious issue.
For obese people as well as those attempting to reduce weight and lead healthier lives, Intermittent fasting offers numerous advantages. It can enhance glucose metabolism and lower inflammation and body fat. In fact, although intermittent fasting is used to lose weight, its variant, alternate day fasting (ADF) has also been shown to benefit individuals who are not obese by reducing triacylglycerol, C reactive protein, and leptin while raising adiponectin and low-density lipoprotein particle sizes. Let’s know the benefits of intermittent fasting, how it works, and how to do it.
What is Intermittent Fasting?
Intermittent fasting is a structured eating pattern in which you eat during a specific period and fast for the remaining hours or days.
For example, with the 16/8 intermittent fasting method, you eat within an eight-hour window and fast for approximately 16 hours.
The fasting period does not necessarily mean avoiding food for an entire day. Several intermittent fasting approaches have been studied, including daily time-restricted eating, 5:2 fasting and alternate-day fasting.
The goal is not simply to eat less. The timing of food intake can change how the body uses stored energy between meals.
How Does Intermittent Fasting Work?
After you eat, the body primarily uses glucose from the recent meal for energy. As the fasting period continues and available glucose stores are used, the body increasingly relies on stored fat and produces ketones for energy.
This change in energy use is sometimes referred to as metabolic switching. Research suggests that fasting-related metabolic changes may influence glucose regulation and other cellular processes. However, researchers are still studying how these mechanisms translate into long-term health benefits in humans.
Intermittent fasting may also naturally reduce overall calorie intake for some people because there is less time available for eating. However, the quality and quantity of food consumed during eating periods still matter.
What are Benefits of Intermittent Fasting?
Research has identified several potential benefits of intermittent fasting. However, results differ depending on the fasting method, duration, diet quality and individual health status.
1. May Support Weight Management
Intermittent fasting can help some people lose weight, particularly when it leads to a reduction in overall calorie intake.
A fasting schedule may make it easier for some people to control meal timing and reduce frequent snacking. However, eating large amounts of high-calorie foods during the eating window can reduce or eliminate the potential benefit.
There is no single amount of weight that everyone should expect to lose through intermittent fasting. Results depend on factors such as calorie intake, physical activity, age, body composition and overall health.
2. May Improve Blood Sugar and Insulin Regulation
Some studies suggest that intermittent fasting may improve fasting blood glucose, insulin levels and insulin sensitivity in certain people.
However, people with diabetes need particular caution because fasting can affect blood glucose levels and may require changes to medication or meal timing. Anyone taking diabetes medication should discuss fasting with their doctor before starting.
3. May Support Heart Health
Research has reported improvements in some cardiovascular risk factors with intermittent fasting, including measures such as blood pressure and other metabolic markers.
However, intermittent fasting should not be considered a replacement for prescribed treatment, a heart-healthy diet, exercise or other recommended lifestyle measures.
4. May Improve Some Metabolic Health Measures
Intermittent fasting and time-restricted eating are being studied for their effects on body weight, glucose regulation and other metabolic health markers.
The evidence is promising, but long-term effects are still being investigated. Research has not established that intermittent fasting is universally better than other healthy approaches to eating.
5. May Influence Cellular and Brain Health
Fasting can trigger metabolic and cellular responses that are being studied for their potential effects on inflammation, cellular stress and brain health.
Some findings, particularly relating to neurological disease and ageing, come from animal or early-stage research. More human research is needed before intermittent fasting can be considered a proven method for preventing conditions such as Alzheimer’s disease or extending lifespan.
What are the Methods of Intermittent Fasting?
Intermittent fasting can be done by a variety of methods, but they all entail dividing the day or week into eating and fasting times. You either eat nothing at all or very little during the fasting periods. These are the most widely used techniques:
- 16/8 Method: Also known as the Leangains protocol, it entails breakfast skipping and limiting your daily eating window to eight hours, or 12:00 p.m. – 8:00 p.m. After that, you observe a 16-hour fast.
- Eat-Stop-Eat: With this method you have to fast for 24 hours, once or twice in a week, like skipping meals from one from dinner to next day’s dinner.
- 5:2 Diet: With this method, you can eat normally for the other five days of the week, but have to consume only 500–600 calories on two nonconsecutive days.
What Can You Eat and Drink During Intermittent Fasting?
The answer depends on the fasting protocol, but during a typical calorie-free fasting period, water is generally appropriate. Some approaches also allow zero-calorie beverages such as unsweetened tea or black coffee.
During the eating window, focus on balanced, nutritious meals rather than compensating for the fasting period by overeating.
A healthy meal can include:
- Protein-rich foods
- Vegetables
- Fruits
- Whole grains
- Pulses
- Nuts and seeds
- Healthy sources of fat
Intermittent fasting should not be used as a reason to replace nutritious meals with highly processed or calorie-dense foods.
What Are the Side Effects of Intermittent Fasting?
Some people experience temporary side effects when beginning intermittent fasting.
Possible effects include:
Hunger
Headache
Fatigue
Dizziness
Irritability or mood changes
Constipation
Difficulty concentrating
Changes in sleep
Difficulty maintaining adequate nutrition or hydration
The experience can vary depending on the fasting schedule, diet, hydration, medications and individual health.
Longer fasting periods are not necessarily better. Extended fasts lasting 24 hours or more may carry additional risks and should not be undertaken without appropriate medical guidance.
Is Intermittent Fasting Safe?
For some healthy adults, intermittent fasting can be incorporated into a balanced lifestyle. However, safety depends on the fasting method, duration, nutritional intake and individual health.
Current research suggests potential benefits, but important questions remain about the long-term effects of intermittent fasting in humans.
A gradual and sustainable approach may be more practical than starting with prolonged fasting periods. If you have a medical condition or take regular medication, consult a healthcare professional before beginning.
Who Should Avoid Intermittent Fasting or Seek Medical Advice?
Intermittent fasting is not appropriate for everyone.
Speak with a doctor before starting intermittent fasting if you:
- Have diabetes or problems with blood sugar
- Take medicines that need to be taken with food
- Are pregnant or breastfeeding
- Have a current or previous eating disorder
- Have a chronic medical condition
- Are underweight or at risk of malnutrition
- Are considering prolonged or restrictive fasting
- Have concerns about dizziness, fainting or other symptoms during fasting
Children and adolescents should not start restrictive fasting diets without appropriate medical supervision.
People with health conditions should discuss the safety of fasting with their healthcare professional before changing their eating pattern.
Intermittent Fasting and Diabetes
Intermittent fasting is being studied for its potential effects on weight, insulin sensitivity and blood glucose.
However, fasting can also increase the risk of low or high blood sugar in people with diabetes, particularly when medications are involved.
If you have diabetes, do not change your meal timing or diabetes medication on your own. A doctor or qualified healthcare professional can help determine whether a fasting schedule is appropriate and whether medication or monitoring needs to be adjusted.
Conclusion
Restricting your eating window and occasionally fasting can have positive health effects, as long as you consume only nutritious foods. It’s a simple, yet highly effective, way to enhance your metabolic health and reduce your body fat. However, taking the right advice from an expert nutritionist can guide you better in your intermittent fasting journey. If you’re considering intermittent fasting, consult the best dietitian nutritionists in Mumbai at Asian Heart Hospital, who can help you design a safe and personalized plan.
FAQs
Q1: What is intermittent fasting?
A: Intermittent fasting is an eating pattern that alternates between periods of eating and fasting. It focuses primarily on when you eat rather than prescribing one specific type of food.
Q2: What is the 16/8 intermittent fasting method?
A: The 16/8 method involves fasting for approximately 16 hours and eating within an eight-hour window. It is one of the most commonly discussed forms of time-restricted eating.
Q3: What are the benefits of intermittent fasting?
A: Potential benefits include support for weight management and improvements in some blood sugar, blood pressure and metabolic health measures. However, results vary and long-term benefits are still being studied.
Q4: Does intermittent fasting help with weight loss?
A: Intermittent fasting may help with weight loss when it results in reduced overall calorie intake. However, weight-loss results vary between individuals and depend on diet, physical activity and other factors.
Q5: What can I drink while fasting?
A: Water is generally suitable during a calorie-free fasting period. Some fasting approaches also allow zero-calorie beverages such as unsweetened tea or black coffee.
Q6: What are the side effects of intermittent fasting?
A: Possible side effects include hunger, headache, fatigue, dizziness, irritability, constipation and changes in sleep. More restrictive fasting schedules may increase the risk of adverse effects.
Q7: Can people with diabetes do intermittent fasting?
A: Some people with diabetes may be able to follow a fasting schedule under medical supervision. However, fasting can affect blood glucose and medication requirements, so people with diabetes should consult their doctor before starting.
Q8: How long should you fast?
A: There is no single fasting duration that is appropriate for everyone. The 16/8 method is one commonly used approach, but the appropriate schedule depends on individual health, lifestyle and nutritional needs.
Q:9 Is intermittent fasting good for everyone?
A: No. Intermittent fasting is not suitable for everyone. People who are pregnant or breastfeeding, have certain medical conditions, take specific medications or have a history of eating disorders should seek professional medical advice before fasting.
Disclaimer: This article provides general health information and does not replace professional medical advice, diagnosis or treatment. Individual dietary needs and fasting recommendations may vary.
