Fasting on Tisha B’Av With Diabetes? Here’s How to Do It Safely

For most people, Tisha B'Av is challenging enough. For people living with diabetes, however, fasting during the height of the Israeli summer can raise additional questions and concerns. Is fasting safe? What precautions should be taken? And when does health take precedence over fasting?

Experts emphasize that every case is different. While many people with diabetes can fast safely with proper preparation and medical guidance, others may be advised not to fast at all. Understanding the risks and planning ahead can help make the day safer and more manageable.

Diabetes and Fasting: What Are the Risks?

Diabetes is a chronic condition that affects the body's ability to regulate blood sugar levels. During a long fast, especially in hot weather, blood sugar levels can become unstable, increasing the risk of complications.

The most common concerns include:

• Hypoglycemia (low blood sugar)

• Hyperglycemia (high blood sugar)

• Dehydration

A less common but potentially serious complication is diabetic ketoacidosis, particularly among people with type 1 diabetes.

In the past, many physicians routinely advised people with diabetes not to fast. Today, thanks to advances in treatment and glucose-monitoring technology, many patients are able to fast safely under proper medical supervision. Nevertheless, fasting is not appropriate for everyone, and protecting one's health always comes first.

Speak With Your Doctor Before the Fast

Anyone living with diabetes should consult their treating physician before deciding to fast, especially if they use insulin or other glucose-lowering medications.

A doctor can assess your individual risk level and determine whether fasting is advisable. In some cases, medication schedules or dosages may need to be adjusted beforehand.

Modern continuous glucose monitoring (CGM) systems have also made fasting safer for many people. These devices provide real-time glucose readings throughout the day, allowing both patients and healthcare providers to identify trends and respond before blood sugar levels become dangerous.

Preparing for Tisha B'Av

Good preparation begins well before the fast starts.

On the day before Tisha B'Av, it is recommended to eat balanced meals at regular intervals. Complex carbohydrates such as whole wheat bread, whole wheat pasta, brown rice, and sweet potatoes provide steady energy because they digest more slowly.

Protein-rich foods such as fish, chicken, eggs, legumes, and dairy products can help increase satiety and support more stable blood sugar levels. Healthy fats from foods such as avocado, nuts, and olive oil may also help.

It is wise to avoid very salty, spicy, or heavily fried foods, which can increase thirst and discomfort during the fast.

Hydration is especially important. Drinking sufficient water throughout the day before the fast can help reduce the risk of dehydration. Sugary beverages, excessive caffeine, and alcohol are best avoided.

During the Fast

People with diabetes should continue following their physician's instructions regarding medications and glucose monitoring.

Checking blood sugar does not break the fast and should not be avoided. In fact, regular monitoring is one of the most important safety measures during the day.

Because Tisha B'Av falls during the summer, it is also important to minimize exposure to extreme heat. Staying in air-conditioned or shaded areas, avoiding strenuous physical activity, and conserving energy can reduce the risk of dehydration and blood sugar fluctuations.

Know When to Break the Fast

Health always takes priority.

Signs of hypoglycemia may include:

• Weakness

• Sweating

• Shakiness

• Rapid heartbeat

• Dizziness

• Confusion

• Intense hunger

If blood sugar drops to a dangerous level or significant symptoms develop, the fast should be broken immediately.

Signs of hyperglycemia and dehydration may include:

• Excessive thirst

• Dry mouth

• Dizziness

• Fatigue

• Weakness

Medical attention should be sought if symptoms become severe.

Symptoms such as nausea, vomiting, abdominal pain, fruity-smelling breath, confusion, or rapid breathing may indicate diabetic ketoacidosis, a medical emergency that requires immediate treatment.

Breaking the Fast Safely

Many people naturally gravitate toward carbohydrate-heavy foods after a fast, but people with diabetes should be especially careful.

It is generally recommended to begin with water and a light snack, then gradually move on to a balanced meal that includes protein, vegetables, and controlled portions of carbohydrates.

Checking blood sugar before and after eating can help ensure a safe transition back to regular eating.

Most importantly, avoid overeating. Trying to "make up" for an entire day of fasting with one large meal can lead to uncomfortable blood sugar spikes and other complications.

Health Comes First

Fasting can be a meaningful spiritual experience, but it should never come at the expense of personal safety. Anyone living with diabetes should discuss their plans with a healthcare provider before Tisha B'Av and follow medical advice carefully.

With proper preparation, monitoring, and guidance, many people with diabetes can navigate the fast safely. When fasting is not medically advisable, preserving one's health is itself an important Torah value.

Prof. Julio Weinstein is a diabetes specialist at the DMC Center for Diabetes Treatment.