Nausea is a common side effect of diets that are too low in calories or do not contain a sufficient amount of carbs or sodium. Visual disturbances may or may not accompany this symptom, but if you experience any changes in your vision, seek medical attention, as this could be serious. Tell your doctor about the diet you are on, as well as the other side effects you are experiencing.
Not Enough Calories
If you are dieting to lose weight, you need to cut back on the number of calories you consume. However, restricting calories too much can be detrimental to your health. Unless you are under the supervision of a doctor, do not consume fewer than 1,100 calories a day. Eating less than this may not give you the nutrients you need, and it can also cause fatigue, hair loss, gallstones, intolerance to cold, nausea, diarrhea and other types of digestive upset. If you begin to experience these symptoms from a very low calorie diet, or if you develop visual disturbances, seek medical attention.
Not Enough Carbs
Many fad diets require you to restrict carbohydrates. While certain carbs are full of sugar and have little to no nutrients, others are essential for your energy production and other bodily functions. A diet that limits or eliminates carbohydrates can cause headaches, dizziness, weakness, fatigue and digestive upset. If you develop these symptoms, especially if your dizziness is accompanied by changes in vision, seek medical attention. If you consume fewer than 20 grams of carbs a day, you can also develop ketosis, which is a buildup of ketones in your blood that results when your body breaks down stored fat. Ketosis can cause nausea, headaches and mental exhaustion.
Too Much Water
When dieting, you may be drinking a lot of water in an effort to keep hunger at bay or to rehydrate after strenuous workouts. Water is essential for life, but drinking too much while also restricting your calories can cause adverse effects. Particularly if your diet is low in protein and sodium, consuming a large amount of fluids can cause your sodium levels to deplete, resulting in a condition known as hyponatremia. Signs of hyponatremia include nausea, vomiting, dizziness, confusion, fatigue, muscle spasms and even unconsciousness. Seek medical attention if you experience these, visual disturbances or other symptoms of hyponatremia.
Nausea and visual disturbances may be the sign of an underlying health problem that is unrelated to your diet. Seek medical attention if you experience these symptoms or if you believe your diet may be lacking certain essential nutrients. If you need help designing a diet that will help you achieve your health goals while still providing adequate nutrition, consider consulting a licensed dietitian.