Fasting: Types, Benefits, Safety Tips, and What to Eat

What Is Fasting?

Fasting means voluntarily going without food for a defined period. Depending on the type, you may continue drinking water and other calorie-free fluids, or you may avoid both food and fluids.

How Does Fasting Affect Your Body?

When you eat, your body uses some nutrients from the meal to generate energy, and stores some of the excess energy for later use. This energy is stored in the form of glycogen and fats. During a period without food, your insulin levels fall, and your body begins using the stored energy.

As the fasting period increases, glycogen, the stored form of glucose, becomes less available, and fat becomes a more prominent energy source.

What Are the Different Types of Fasting?

There is no single fasting schedule that works for everyone. You can choose a method based on how frequently you fast and how long your eating window lasts.

Here’s a breakdown of the most common approaches, based on the duration of fasting and eating windows:

Type of Fasting	How It Works
Intermittent Fasting	An eating pattern that alternates between eating and fasting windows. A common example is 5:2 fasting, where you eat regular meals for 5 days a week and fast for the next 2 days.
Time-restricted Fasting	A subtype of intermittent fasting that you can practice within a day. The approach is to restrict eating to a time window of six to eight hours a day, and fast for the remaining 16 to 18 hours.
Alternate-day Fasting	Alternates between usual eating days and low- or no-food days.
Religious Fasting	Practised on days of cultural or religious significance. You may consume permitted food items and fluids, or you may go without eating or drinking anything for a set period.
Water Fasting	Only permits drinking water and restricts consuming any calories for a specific time frame, usually 24 to 48 hours. This form of fasting carries greater risks and should be discussed with a doctor.
Medical Fasting	Restricts consuming food and certain fluids for a set period of time, to prepare for lab tests or procedures. For example, you are required to maintain an overnight fast of 8 to 12 hours in order to measure your fasting blood sugar levels.

What Is a Fasting Diet Plan?

A fasting diet plan is the food regimen you follow before, during, and after your fasting windows. Even when you are on a fasting diet, your body still needs adequate protein, fibre, vitamins, minerals and other nutrients. So, the meals you consume during your eating hours or days have to meet those requirements.

If you plan to keep your fasting periods prolonged (24+ hours), you may benefit from following these dietary tips:

• Before the fast: Gradually lighten your diet for 1 to 2 days with warm, easy-to-digest foods such as rice stew.
• During the fast: Unless you are on a religious fast, keep sipping water throughout the day to prevent dehydration and hunger headaches.
• After the fast: Reintroduce solid foods gradually. It is preferable to start with food that is lighter on the gut.

Note: Consult your family physician before going on a prolonged fast.

What Should You Eat Before Starting a Fast?

Before fasting, choose a balanced meal rather than trying to eat as much as possible. Make sure you include a source of protein such as dal, eggs, curd, paneer, fish, or lean meat, along with vegetables, whole grains or other high-fibre carbohydrate sources. Healthy fats such as nuts and seeds can also contribute to a satisfying meal.

Adequate fluids are equally important, particularly if you will not be drinking during the fasting period.

What Should You Eat After Fasting?

When you break your fast, you do not need a very large meal. Start with a balanced meal containing protein, fibre-rich carbohydrates, vegetables, and healthy fats. Your overall diet matters more than trying to compensate for the fasting period with highly processed or calorie-dense foods.

What Are the Benefits of Fasting?

Fasting has been linked to several health benefits, spanning metabolic and cardiovascular health. The eating pattern has been a subject of extensive clinical research, with more of its benefits still being studied.

Across multiple studies, several advantages have been observed, and here’s what the evidence points to:

• Fasting can reduce visceral fat: A study shows that time-restricted fasting can decrease visceral fat and weight.
• Fasting can reduce the risk of Type 2 diabetes: A 2023 study showed that intermittent fasting can increase insulin sensitivity, which lowers the risk of Type 2 diabetes.
• Fasting can help with weight loss: Limiting the intake of calories for longer periods of time can make it easier to lose weight.

These effects vary between individuals and fasting methods. A 2025 umbrella review found associations between intermittent fasting and several health outcomes, but also highlighted variation in the evidence and the need to interpret findings according to the quality of the underlying research.

Fasting may therefore be useful for some people as a structured eating pattern, but it should not be presented as inherently healthier than every other balanced approach.

Does Fasting Help With Weight Loss?

Fasting can help with weight loss by regulating your calorie intake over time. When you have fewer hours available for eating, you may naturally consume fewer calories. That said, if you compensate for the fasting period by eating larger portions or high-calorie foods during your eating window, you may not notice a substantial change.

The evidence supports this distinction. In a 12-month clinical trial, people following time-restricted eating with calorie restriction lost weight, but their weight loss was not significantly different from people following daily calorie restriction alone.

So, if fasting helps you eat in a sustainable way, it may be a useful option, but it is not the only way to lose weight.

What Is a Healthy Fasting Schedule?

There is no single fasting schedule that can be labelled the healthiest for everyone. A schedule is more likely to work when it fits your daily routine, allows you to meet your nutritional needs and does not leave you regularly exhausted, dizzy, or excessively hungry.

How Often Should You Fast?

How often you fast depends on the type of fasting you choose. If you are considering intermittent fasting, a consistent daily eating window may be easier to manage than frequent prolonged fasts. You do not need to progress to increasingly longer fasting periods to make your routine more effective.

Your goal should be a sustainable eating pattern rather than seeing how long you can tolerate hunger.

How Can You Choose a Fasting Schedule That Suits You?

Start by considering your usual meal timings, work schedule, sleep pattern, physical activity and health needs.

A moderate overnight fasting period may be easier to maintain than an aggressive fasting schedule. You should also make sure that your eating window gives you enough opportunity to consume nutritious meals.

If fasting makes it difficult for you to meet your nutritional needs or affects your daily functioning, it may not be the right eating pattern for you.

What Are the Side Effects of Fasting?

The side effects of fasting can include hunger, headache, fatigue, dizziness, nausea and digestive discomfort. These symptoms generally get more intense as the fasting period becomes longer or more restrictive.

Can Fasting Cause Headaches or Dizziness?

Yes. Headaches or dizziness may occur during fasting, particularly if you are not adequately hydrated or are accustomed to regular meals and suddenly change your eating pattern.

If you experience significant dizziness or feel as though you may faint, you should stop fasting rather than trying to push through the symptoms.

Can Fasting Affect Your Energy Levels?

You may feel more tired or less energetic during a fasting period, particularly when you first begin. Your response to fasting can also depend on your sleep, hydration, physical activity and overall calorie and nutrient intake.

If fasting consistently interferes with your ability to work, exercise or perform everyday activities, reconsider whether the schedule is appropriate for you.

Can Fasting Cause Digestive Problems?

Changes in meal timing can affect your digestive comfort. Some people may experience bloating, constipation or discomfort, while others may find that a structured eating window suits their digestion.

Eating very large meals after fasting can also make you feel uncomfortable.

If you have persistent abdominal pain, vomiting, significant diarrhoea or other ongoing digestive symptoms, do not assume that fasting is the cause or solution. Speak to a healthcare professional.

Who Should Avoid Fasting or Seek Medical Advice Before Fasting?

Fasting is not appropriate for everyone, and you should speak to a doctor before starting if you have a medical condition or take regular medicines.

Is Fasting Safe During Pregnancy or Breastfeeding?

Pregnancy and breastfeeding increase your nutritional requirements, so intentional fasting for weight loss should not be started during this time without medical guidance.

Can Children and Teenagers Fast?

Children and teenagers are still growing and have different energy and nutrient requirements. So, restrictive fasting schedules should not be introduced without appropriate medical and nutritional guidance.

Can You Fast While Taking Regular Medicines?

It depends on the medicine. Some medicines need to be taken with food, while others can affect blood pressure, blood glucose or hydration. Changing your food intake without considering your medicines can therefore create problems.

If you take regular medication, check with your doctor before changing your eating pattern.

Should You Fast If You Have an Existing Health Condition?

Not without checking first. You should take particular care if you have diabetes, kidney disease, cardiovascular disease, gastrointestinal conditions, or another chronic condition. If you have diabetes, you may be at risk of blood glucose fluctuations and dehydration during fasting, particularly with certain medicines. You would also need to check with your doctor if you have a history of eating disorders.

Mool Health’s Perspective on Fasting

At Mool Health, we believe fasting can be a useful eating pattern for some people, but it is not a shortcut to better gut health.

If you choose to fast, focus on consistency, adequate nutrition and a schedule you can realistically maintain. You do not need to follow an extreme fasting routine to benefit from better eating habits. Your health goals should determine the approach, not the number of hours you can go without eating.

You can take the Mool Health Gut Test to understand your gut health and identify patterns in your symptoms, food habits and lifestyle. This personalised assessment can help you better understand what your gut may need rather than following a fasting routine simply because it is popular.