Weight Loss & Fainting

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While creating a caloric deficit is essential to losing weight, limiting your nutritional intake may deplete your energy stores and interfere with your ability to mentally focus. When your diet is excessively restrictive, it can cause headaches, dizziness and even fainting. Knowing the reasons for fainting episodes during weight loss can help you ward off this potentially dangerous occurrence.

Causes of Fainting

Medically known as syncope (sin-co-pee), fainting is defined as a transient disruption of blood flow to the central nervous system, which is made up of the brain and spinal cord. Disruptions may be caused by any number of situations including medications, excessively low blood pressure, blood pooling in the lower extremities, and inadequate nutrition. A sudden shock can trigger fainting when the sympathetic nervous system (the fight-or-flight system) is overstimulated.

Mineral Deficiency and Fainting

Mineral deficiency can cause dizziness and fainting. Your body uses dietary iron to manufacture the protein hemoglobin, a component of red blood cells. Hemoglobin is responsible for carrying oxygen to the cells throughout your body, including the brain. If your blood does not contain enough hemoglobin, the brain tissues may not receive adequate oxygen. Similarly, inadequate sodium and potassium levels can influence heart rate and blood pressure, and can decrease blood flow to the brain. Low sodium diets and diets that do not contain red meat, dark poultry or dark green vegetables may cause mineral depletion over time.

Low Blood Glucose and Fainting

Low blood glucose, or hypoglycemia, can be an underlying cause of fainting. Your brain and other vital organs rely almost exclusively on glucose to function. When blood glucose becomes excessively low, as it will on a restricted carbohydrate diet, fainting can occur. Recovery from the faint is brought about when the central nervous system sends a message to the liver to break down glycogen stores to elevate circulating glucose. If you restrict your carbohydrate consumption while attempting to work out vigorously, your muscles compete with your brain for glucose, putting you at a high risk of fainting.

Dehydration and Fainting

Inadequate hydration can also cause fainting. People become dehydrated when the water leaving the body exceeds the amount being put back in. Your body loses water through breathing, sweat, urine and feces. Water can be lost from the blood vessels as well, interfering with blood circulation. When circulation to the central nervous system is diminished, fainting can occur. Because we replenish water through the food and beverages we ingest, decreasing your food consumption without increasing your fluid consumption can lead to dehydration. Relying on diet soda, coffee and tea for fluids may cause further dehydration, as they function as diuretics.

Weight Loss Guidelines to Prevent Fainting

Dizziness and fainting can be avoided by adopting a common-sense approach to weight loss. Staying hydrated by drinking adequate amounts of water, eating a variety of healthy foods that contain vitamins and minerals, eating small meals throughout the day to maintain glucose levels and eating within an hour before your workout are all strategies that will keep your brain functioning at optimal levels. Avoid starvation diets or diets that do not include a variety of food.

When to Seek Intervention

Some people are more susceptible to fainting than others. If you have a history of syncope, speak to your health care provider before beginning a weight loss regimen. You should also seek intervention if you faint suddenly without warning symptoms, such as light-headedness, if you faint more than twice in a 24-hour period, if you faint after a head injury, or if you have a history of heart disease or seizures.