The bottom line: Fasting to lose weight doesn't make any sense and can cause serious health problems.

What about a modified fast?

Simple fasting involves eating nothing and drinking only water. Obviously, we can't live for long on that kind of program. Today's modified fasts often use fresh fruit or vegetable juices, and sometimes brown rice, to treat allergies, arthritis, psoriasis and even high blood pressure. Little scientific research on modified fasts has been reported, yet the results may be promising.

The bottom line: Supervised by a medical professional, a two- or three-day modified fast may in fact help decrease symptoms of some chronic illnesses. To maintain those benefits, a healthy diet and lifestyle should be followed after the fast.

Is fasting safe?

Certain people should never attempt any type of fast unless they are strictly monitored by their physician. Anyone with diabetes, heart disease, or kidney or liver disease should avoid fasts. Pregnant or breastfeeding women and children should also avoid fasts. Any fast carries the risk of dehydration and altered electrolyte levels, which can trigger sudden heart problems.

Scientific research (not personal promotions and beliefs) shows that fasting has few health benefits. The rapid weight loss seen with fasting is due to water loss, which can lead to fatigue and dizziness. Fasting doesn't cleanse our body; in fact, the opposite is true. Fasting causes the production of ketones, which can put a burden on the kidneys. Prolonged fasting can lead to muscle wasting and depletion of essential minerals such as calcium, phosphorus, sodium and potassium.