Lightheadedness can occur if your blood pressure drops while you are exercising or from low blood sugar when you skip meals. Various diseases and disorders can produce side effects that mimic low blood sugar. According to the Physician's Committee for Responsible Medicine, any unbalanced diet designed to produce weight loss that's sustained for long periods of time can cause physical problems that often present with symptoms of lightheadedness, headaches and fatigue.
The effects of weight loss vary between individuals. Any diet that strictly restricts essential nutrients can lead to low blood pressure that causes lightheadedness and dizziness. Anemia produces lightheadedness and is caused by a lack of sufficient vitamin B-12 and folate in the diet. Hypoglycemic shock can occur when the body becomes dehydrated if you don't take in enough fluids. Dehydration can also cause a drop in blood pressure, resulting in light-headedness. Sip water throughout the day to help ensure adequate fluid intake.
When the body does not receive sufficient calories from glucose, hypoglycemia can occur. Low blood sugar, another name for hypoglycemia, can result in dizziness and lightheadedness when sugar levels fall too low. The most effective source of glucose is carbohydrates from sources such as bread, potatoes, cereal, milk, fruit and sweets. In addition to the lightheadedness, you also may experience hunger pains, sweating, confusion and shakiness when blood sugar levels drop.
People with diabetes are subject to bouts of hypoglycemia when they don't eat sufficient carbs or when they mismanage their insulin therapy. Some diabetes medicines or combination of pills can cause hypoglycemia. Blood glucose levels can drop if diabetics eat too little at meals or if they skip meals in an effort to lose weight. An increase in physical activity aimed at weight loss also can cause the lightheadedness associated with hypoglycemia.
Other types of hypoglycemia can produce symptoms of lightheadedness during weight loss efforts. Reactive hypoglycemia causes symptoms to appear about four hours after eating. This type of insulin reaction usually is caused by an underlying medical condition such as enzyme deficiencies or stomach problems. Skipping meals or eating large meals can bring on the symptoms. Eating a high-fiber diet also can help prevent the dizziness. Fasting hypoglycemia occurs when dieters skip meals or sometimes upon waking. The condition is exacerbated by dieting and can be caused by a tumor or hormonal deficiency.
You may not have to break your diet completely if you experience lightheadedness. A quick fix with a handful of nuts, a few crackers, a piece of cheese or a glass of juice typically clears up the dizziness within 15 minutes or less. Prevent further bouts of hypoglycemia symptoms while you're losing weight by eating small meals about every three hours.
- University of Maryland Medical Center: Low Blood Pressure
- Physicians Committee for Responsible Medicine: Analysis of Health Problems Associated with High-Protein, High-Fat, Carbohydrate-Restricted Diets
- University of Maryland Medical Center: Hypoglycemia
- American Academy of Family Physicians: Orthostatic Hypotension