Side Effects of Liquid Fasting Diets

Liquid fasting diets are a type of fad diet, sometimes promoted for weight loss, and other times based on the idea that your body is filled with toxins that will be removed by an all-liquid diet. Starving your body of adequate nutrition can have numerous and serious side effects, and can endanger your health. By understanding the risks and side effects of liquid fasting diets, you can make healthier dietary choices that will not only help you lose weight, but also improve your health and prevent disease.

A couple begin juicing their fruits and vegetables for their liquid diet. Credit: ElNariz/iStock/Getty Images

Carbohydrates and Energy

Contrary to the claims of many fad diets, carbohydrates are not all bad. Whole-grain carbohydrates, such as whole-wheat bread, oats and bran are an important part of your diet. Whole-grain carbohydrates give your body energy and maintain steady blood sugar levels, which helps prevent type 2 diabetes, notes Harvard School of Public Health. Liquid fasting diets can rob your body of the energy it needs to maintain physical activity levels, which is detrimental to a healthy heart. Side effects of eliminating carbohydrates can include fatigue and dizziness due to blood sugar fluctuations.

Fiber and Digestion

Although 100 percent fruit and vegetable juices may offer the same vitamins and minerals as whole vegetables and fruits, you lose much of the beneficial fiber. Fiber serves several important functions. Water-soluble fiber helps remove low-density lipoprotein, LDL, or bad cholesterol from your bloodstream to prevent high cholesterol. Insoluble fiber aids digestion by pushing waste through your intestines to prevent constipation. Liquid fasting diets greatly reduce your intake of fiber, leading to digestion problems and increasing your risk for high cholesterol.


Malnutrition is a significant and dangerous side effect of liquid fasting diets. All-liquid diets greatly reduce your intake of calories and the nutrients your body needs to maintain organ function and your immune system. Malnutrition can cause gallbladder problems and potentially fatal heart rhythm abnormalities. Additional side effects you can expect if fasting is leaving you dangerously malnourished include brittle nails, sensitivity to cold, fatigue and digestive problems, such as diarrhea or constipation.

Protein and Muscle

Liquid fasting diets also rob your body of protein. Inadequate intake of protein can cause muscle loss and weaken your heart and respiratory system, as well as your immune system. This can increase your risk for heart problems and reduce your ability to fight off disease.

Additional Considerations

All-liquid diets and fasting can be dangerous and unhealthy. Always consult your physician before beginning any extreme diet plan. Your physician can assist you in finding safe ways to lose weight that will offer adequate nutrition and improve your overall health.

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