Diet Shakes: Sipping to Slimness

From the WebMD Archives

You meant to drop a few pounds this spring, but you never got around to eating less and exercising more on a regular basis. With summertime here, you're considering how to shed that extra weight, and fast. Are diet shakes the ticket to a slimmer you? Perhaps.

Diet Shakes Pros and Cons

"I prefer people to lose weight on a balanced, low-fat diet that includes lots of fruits and vegetables," says Cathy Nonas, RD, a spokeswoman for the American Dietetic Association and director of Obesity and Diabetes Program at North General Hospital in New York City. "However, I realize that approach doesn't work best for everyone, so sometimes I recommend liquid meal replacements as part of a healthy eating plan."

Other nutritionists disagree. "Whole foods provide a much better balance of nutrients than meal replacements," says Hillary M. Wright, MEd, RD, a nutrition counselor at Harvard Vanguard Medical Associates in Boston. "Plus, using real foods forces you to make choices that help you maintain weight loss in the long run."

Australian researchers writing in the Journal of Nutrition found that diet shakes, also called meal replacements, were just as effective for producing weight loss when compared with conventional, structured weight loss diets. However, study subjects using diet shakes were more positive about dieting in general, rating their eating plan more favorably for its convenience than those on the regular food diet. That may be just the motivation some people need to diet.

Nonas says diet shakes are particularly useful for jump-starting weight loss (health experts generally recommend limiting weight loss to no more than about 2 pounds a week). As with meal replacement bars or low-calorie entrees, diet shakes help you keep tight control on calories. "They are particularly useful for women who have very little leeway in calorie intake and who can't lose weight when they exceed their calorie quota even by a little," Nonas says.

Of course, diet shakes of any type won't work toward weight loss unless you eat fewer calories than you burn every day. To use diet shakes and meal replacement beverages most effectively, determine a calorie allowance for weight loss. You may be tempted to slash daily intake to 1,200 calories for fast results, but 1,500 calories may help you stick with your eating changes longer. Include exercise, which aids weight control and promotes good health.

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Diet Shakes: The Simplest Way to Diet

Diet shakes and other meal replacements are a boon when you lack the time or motivation to shop for and prepare balanced meals. They also help when you just don't want to think too hard about what to eat to lose weight. Even Wright admits they are useful -- to a point. "If you are consistently missing a certain meal, such as breakfast, then a meal replacement shake is better than nothing. That's because studies show eating breakfast fosters long-term weight control."

The makers of some ready-to-drink meals recommend sipping one each for breakfast and lunch, and eating a sensible or healthy low-fat dinner, keeping food preparation to a minimum. You may make it through the day on automatic pilot by relying on diet shakes, but you can't completely escape thinking about calories and other nutrients. Even when diet shakes stand in for two out of three meals, you still need to interpret "sensible" and "healthy low-fat" when determining dinner.

"Dinner is where people who use meal replacement shakes can get into trouble," Nonas says. That's because many people eat at night to relieve tension from the day. Going overboard at dinner (and after) can effectively wipe out the calorie deficits that contribute to weight loss. Limiting dinner to 4 to 5 ounces of cooked poultry, seafood, or lean meat; a medium baked or sweet potato or a 1/2-cup cooked rice or pasta; and a cup of cooked broccoli or other vegetable seems a sensible way of getting nutrients without excess calories.

You may simply be too hungry to control yourself at the evening meal. If two diet shakes, which can amount to 450 calories or even less, is all you've had by dinnertime, you've only used up about one-third of your daily calorie allotment, so it's little wonder you're ravenous. Two midmeal snacks for a total of 400 calories help take the edge off evening hunger. Another option for keeping evening calorie consumption in check: Eat more at breakfast and lunch and choose a diet shake and salad for dinner instead of a full meal, always working within your calorie allowance.

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How Long Can You Last on Diet Shakes?

Let's say you're losing a safe amount of weight with two diet shakes, two snacks, and a modest dinner every day. How long can you stay on this eating plan? Nonas says many people use the beverages for the bulk of their meals for about three months, then maintain their weight loss for years by substituting a meal replacement shake for one meal on most days.

Research bears that out. In a Journal of the American Dietetic Association study published in 2001, women who lost weight on a reduced-calorie plan that included meal replacement beverages maintained their losses after a year by drinking at least one diet shake a day in place of a regular meal. Their counterparts in the study, who lost weight on a conventional low-fat diet that did not use meal replacement beverages, regained most of their initial weight.

The Bottom Line on Diet Shakes

Diet shakes are not the magic bullet in the battle of the bulge. Used judiciously, they can help you get started on weight loss or help you maintain a healthier weight. "To lose weight or even to eat well while maintaining a healthy weight, you must be a vigilante and defend against the many temptations out there. Meal replacements shakes are easy, but they are also a lot healthier than most other choices you could make," Nonas says.

WebMD Feature Reviewed by Ann Edmundson, MD, PhD on June 20, 2008

Sources

Originally published May 2005.
Medically updated May 2006.

SOURCES: Cathy Nonas, MS, RD, director of the Obesity and Diabetes Program, North General Hospital, New York City. Hillary Wright, MEd, RD, Harvard Vanguard Medical Associates, Boston. The Journal of the American Dietetic Association, "Liquid Meal Replacement vs Traditional Food," March 2001, vol 101. Noakes, M. The American Society for Nutritional Sciences Journal of Nutritio, Aug. 2004; vol 134: pp 1894-1899.
© 2005 WebMD, Inc. All rights reserved.

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