Diet shakes are called meal replacements by nutritionists and weight-loss experts because, in theory, drinking one shake is intended to replace one whole meal. Other types of meal replacements are nutritional bars and pre-packaged entrees. They may seem like an easy solution for weight loss, but do meal replacements work?
Evidence suggests that meal replacement programs can help you lose weight. The Academy of Nutrition and Dietetics recommend that for people who have difficulty with portion control, using meal replacements can be used to lose weight. They stress the importance that meal replacements are only one part of a larger weight management program. Some recent studies have shown how meal replacements can benefit at least short-term weight loss.
One study with United States Army volunteers found that soldiers started on a meal replacement program, when added to education based weight management, had greater weight loss over a 6 month period. However, only 59% of the volunteers in this study continued with the diet for the study period.
Another study also found that meal replacements resulted in more pounds shed than a food-based diet. The study involved 90 obese men and women who were randomized to either a meal replacement program, which included 3-5 meal replacements plus one meal daily, or a 1,000 kcal/daily food diet. Researchers found that rate of weight loss was greater in the group who were on meal replacements (93%) compared to the group on the food-based diet (55%) after 16 weeks. However, many people in the study dropped the diet and only the people that continued the diet were counted.
Weight loss sounds very easy. You just need to eat fewer calories than you use. The trick is that weight loss in the real world, with busy schedules and abundant food choices, is hard. Meal replacements work on the premise that few of us know how many calories we eat each day. Packaged foods may list calorie content but most meals we eat do not. Portion size is also important when it comes to counting calories, and many of us eat more than we realize. An average meal may contain more calories than you think. If you add in snacks and the occasional sweets, not to mention alcohol or other calorie beverages like soda, most of us consume far more calories than we need.
Replacing one or two meals per day with a known quantity of calories will reduce the number of calories you consume. In other words, instead of eating a meal that might have 750 calories, you drink a shake with 250 calories then you will have reduced the usual number of calories you take in by 500. Reducing the number of calories you take in will lead to weight loss over time.
Cutting calories alone is not the best way to achieve and maintain your weight loss goals. Your weight loss plan should also include ways to help you increase your physical activity, medical care if you have a condition or take medication that may be affected by weight loss, and a plan to help you keep the weight off after you reach your goal weight.
Meal replacements are no magic bullet. As with most diets, the reason people who stop using meal replacements regain their weight is because they return to a higher caloric intake. Plus using meal replacements may not teach you how to make healthy choices about food and exercise that will help you maintain your weight loss over time. Meal replacements can also be expensive and may not provide all the nutrients you need.
Talk to your doctor or a dietitian before starting any weight loss program that uses meal replacements. They may be able to provide you with information and other options to help you succeed in weight loss.
Choose My Plate - US Department of Agriculture
Eat Right - Academy of Nutrition and Dietetics
Canadian Society of Exercise Physiology
American Gastroenterology Association medical position statement on obesity. Gastroenterology. 2002;123: 879-881.
Choosing a safe and successful weight loss program. National Institutes of Health website. Available at: http://www.win.niddk.nih.gov/publications/choosing.htm. Updated December 2012. Accessed July 16, 2014.
Davis LM, Coleman C, Kiel J, et al. Efficacy of a meal replacement diet plan compared to a food-based diet plan after a period of weight loss and weight maintenance: a randomized controlled trial. Nutr J. 2010 Mar 11;9:11.
Dietary guidelines for Americans 2010. US Department of Agriculture and US Department of Health and Human Services. Available at: http://www.health.gov/dietaryguidelines/dga2010/DietaryGuidelines2010.pdf. Accessed July 16, 2014.
Diets for weight loss. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 10, 2014. Accessed July 16, 2014.
Obesity in adults. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 9, 2014. Accessed July 16, 2014.
Smith TJ, Sigrist LD, Bathalon GP, McGraw S, Karl JP, Young AJ. Efficacy of a meal-replacement program for promoting blood lipid changes and weight and body fat loss in US Army soldiers. J Am Diet Assoc. 2010 Feb;110(2):268-73.
Weight loss for life. National Institutes of Health website. Available at: http://win.niddk.nih.gov/publications/PDFs/WeightLossforLife_04.pdf. Updated January 2009. Accessed July 16, 2014.
Last reviewed July 2014 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © 2012 EBSCO Publishing All rights reserved.
What can we help you find?close ×