Feeling Shaky and Dizzy While Fasting? Your Guide to Preventing Hypoglycemia and Reactive Lows

This topic represents the single greatest barrier for people trying to adopt intermittent fasting. Countless viewers describe trying to skip a meal, only to be met with terrifying symptoms of low blood sugar: shakiness, weakness, panic, and dizziness. They interpret these scary physical signals as proof that fasting is dangerous or simply "not for them," causing them to abandon a powerful tool for reversing insulin resistance. This experience is incredibly common and reflects a state of poor metabolic flexibility, where the body is so accustomed to a constant supply of carbohydrates that it cannot efficiently switch to burning its own fat for fuel when meals are delayed.

The primary concern is safety and loss of control. Viewers are afraid of passing out at work, in front of customers, or while living alone. These symptoms make life "miserable" and lead to immense frustration, especially when their own doctors don't have answers. Furthermore, there is deep confusion when their lived experience directly contradicts the advice from top experts. When a creator states that low blood sugar shouldn't happen without medication, but a viewer experiences it with a glucose reading of 44 mg/dL, it creates a crisis of confidence in both the expert and their own body.

The collective wisdom emerging from both expert advice and audience struggles points to a crucial tip: You must earn the right to fast. Before attempting to skip meals for extended periods, you first need to stabilize your blood sugar by adopting a low-carbohydrate, healthy-fat diet. This transition period, often called becoming "fat-adapted," teaches your body to efficiently burn fat for fuel. Once your body is no longer dependent on a constant drip of glucose from frequent meals, it can seamlessly switch to using its own fat stores, preventing the dramatic energy crashes that trigger hypoglycemic symptoms.

Two creators in the sources provide key, albeit different, perspectives on this issue, highlighting the gap between physiological theory and real-world adaptation.

• • Dr. Jason Fung: He explains the physiological ideal: in a person not taking diabetes medication, the body should never develop dangerously low blood sugar in response to fasting. He clarifies that the body has robust mechanisms to produce its own glucose (gluconeogenesis) from fat and protein stores. Furthermore, he points to studies showing that during extended fasts, the brain switches to using ketones for energy, making people feel completely normal even with very low blood glucose levels. While scientifically sound, many viewers report that their bodies do not adapt this smoothly, experiencing severe hypoglycemic symptoms without being on medication, which creates confusion and fear.
• • Dr. Eric Berg DC: His model offers a practical solution to this transition problem. He recommends that improving insulin resistance involves 20-30% from a ketogenic diet and 60% from intermittent fasting, implying that the diet should be established first. One commenter perfectly intuits this solution in a question directed at Dr. Berg: "So should I just do keto breakfast, lunch, and dinner for a while, until my body adjusts, and then slowly introduce fasting?". This highlights Dr. Berg's approach as a foundational strategy: stabilize blood sugar with keto meals first to prevent the very hypoglycemic symptoms that derail fasting attempts.

Do not plan to skip breakfast tomorrow. Instead, prepare a savory, high-protein, high-fat meal (like eggs and avocado). Your immediate goal is to prevent a blood sugar crash by starting your day with stable fuel, which is the first step toward earning the ability to fast comfortably.

• Mistake: Jumping into a 16+ hour fast while still eating a diet high in refined carbohydrates.
  Fix: Adapt to low-carb eating first. Give your body at least a week of consistent keto-style meals before you ask it to go without food for an extended period.
• Mistake: Trying to "power through" severe hypoglycemic symptoms like extreme dizziness, disorientation, or panic.
  Fix: This is your body signaling it's not ready. Break your fast with a small, low-carb snack (e.g., a handful of nuts, an avocado, a piece of cheese) to stabilize. This is not a failure; it is a crucial part of calibrating your fasting window.
• Mistake: Confusing electrolyte deficiency with hypoglycemia.
  Fix: Symptoms like headaches, weakness, and muscle cramps can also be caused by a lack of salt, potassium, and magnesium, which are flushed out during the initial phase of low-carb diets. Ensure you are taking electrolytes in your water during your fast.

• • "What if you get hypoglycemic by not eating?"
• • "I have a question: I have a high cortisol and insule resistance. I tried keto but gained weight and also tried IF but my body started shaking around 11am. Help would be much appreciated!".
• • "Last time on a 3 day fast, on the 3rd day I woke up with a 36 glucose reading… also had a fast heart beat and much anxiety… I broke the fast.".
• • "Hey doc im newly type 2 diabetic... I have alot of hypos... Should i ignore hypos n let me body figure it out? Or should i eat as soo as i reach 5 or 4????? Im confused".

Feeling shaky, dizzy, and weak during a fast is a sign of poor metabolic flexibility, not a personal failing or an indication that fasting is inherently wrong for you. It means your body, conditioned by years of frequent carbohydrate intake, has forgotten how to burn its own fat for fuel. The solution, as outlined by creators like Dr. Berg, is to prepare your body first. By adopting a ketogenic diet to stabilize blood sugar and become fat-adapted before you begin intermittent fasting, you can avoid the metabolic rollercoaster and smoothly transition into a state where fasting feels energizing, not frightening.