The pros and cons of high-protein diets
Editor's note: CNN's Dr. Sanjay Gupta answers medical questions submitted by e-mail on "Your Health," which airs at 2:30 p.m. Eastern Time on Saturdays. Questions and answers are posted on CNN.com after the show.

Q: Do protein diets really work? -- J.J. Richa

A: Protein diets have been very controversial. The Atkins diet, the Zone, Protein Power, Sugar Busters and the Stillman diet count on low carbohydrates and high protein. Most people agree that you will lose weight and may even lower your cholesterol -- at least initially.
The problem may lie down the road when your weight stabilizes. At that time, the bad type of cholesterol may become elevated, despite the lower weight.
Many of the ideas behind the diets were once considered far-fetched, but are now held as more mainstream. However, with this diet, as with other types of diets, many people find them hard to stick with and find the weight returns when the diet ends.
There are no quick, easy ways to lose weight without first trying to be as healthy as possible. The American Dietary Association still recommends balanced meals and regular exercise.

Q: Do supplements with promises of burning fat and increasing energy really work? Can they be dangerous to your health? -- Alexandra in Campbell River, British Columbia

A: Well, Alexandra, there is little scientific proof that these fat-burning, energy-increasing pills really work.
Fat-burning pills are generally some combination of herb-based stimulants, and they are supposed to increase energy while stimulating fat burning. Most experts agree there is barely enough evidence that these products have a minor effect, but only when combined with proper diet and regular exercise.
Some ingredients can pose dangers to your health. For example, ephedra can raise blood pressure and even cause heart attacks, arrhythmia or strokes. While these pills can work by increasing your metabolic rate, the same effect can be reached more safely and cheaply simply by exercising more and eating less.