Partial meal replacements safe and effective for weight loss
Dr Gary Egger (well known for his Gut Buster program for men and Professor Trim's weight loss program for men) reviewed the evidence regarding partial meal replacements for weight loss in an editorial for the Medical Journal of Australia in 2006. Complete meal replacements are used in morbidly obese people who usually need to lose a lot of weight before surgery - all meals are replaced with a protein milk shake (also complete in vitamins and minerals) for around 6 weeks. In contrast, partial meal replacements can be used by people wanting to lose some weight but who are not necessarily obese. For initial weight loss, usually two meals a day are replaced with a protein milk shake while maintaining one other main meal in the first few weeks. This is usually followed by replacing one meal a day, usually lunch or dinner, to facilitate further weight loss or for weight maintenance. Results can also be achieved by replacing dinner with such protein shakes only a few times a week and many patients find this sustainable in the long term. His review concluded that clinical trials show that partial meal replacements are safe, acceptable and effective when used as part of an overall low energy diet and result in about 10% loss of body weight in 6-12 months or 6-8% loss in 1-5 years which is greater than weight loss achieved on diet alone.
HEC comment: If protein shakes replace dinner make sure that you have a decent lunch with lots of vegetables and a piece of fish/chicken or meat or eggs or legumes; if you want to go down this path, try replacing only 3 meals a week first as you may still get good results without affecting your entire diet and at this low intake of meal replacements you won't get sick of them; protein shakes can be high in potassium (>200mg/serve) which may interact with some hypertension and heart disease medications - check with your doctor and dietitian before you start their daily use; some protein shakes can be high in added fructose at >4g/serve (added to lower the glycaemic index) which may raise blood pressure, uric acid, triglycerides and aggravate irritable bowel symptoms in some people; if you have trouble managing your snacking behaviour try using half strength meal replacements as a snack replacement!. HECs Dr Kouris and Professor Wahlqvist have also reviewed the research on this topic in the Asia Pacific Journal of Clinical Nutrition and reported similar findings to Dr Eggar.

Soy versus milk based "meal replacements" for weight loss

In a recent study, of overweight men and women, researchers compared the weight loss and blood lipid effects between reduced-calorie milk- and soy-based beverage meal replacements. After 12 weeks on a 1,200-calorie per day diet which included 2 to 4 soy- or milk-based meal replacements, men and women in both groups lost about 8-9 % of their initial body weight. However, people who consumed the soy-based meal replacements experienced significant decreases in total and LDL cholesterol as well as triglycerides compared to people on the milk based meal-replacements . This study confirms previous studies documenting the effectiveness of meal replacements for weight loss but this study also showed that soy based meal replacements have the added benefit of lowering blood fats.

Meal replacements can be helpful in the short term to help people reduce their energy intake for weight loss but a long-term successful weight loss plan should contain a variety of food, be low in saturated fat and calories, and high in nutrients and include at least 30-60 minutes/day walking.

Weight loss and lipid changes with low-energy diets: comparator study of milk-based versus soy-based liquid meal replacement interventions. Anderson, J. W., Hoie, L. H., Journal of the American College of Nutrition 2005 Jun;24(3):210-216

Meal replacements - do they work?

A recent meta-analysis published in the International Journal of Obesity and Related Metabolic Disorders May 2, vol 27 (5) 2003 (pages 37-49) by Heymsfield et al showed that meal replacements result in medically significant weight losses - 7% average weight loss at 3 months and 7-8% at 1 year. Along with the weight loss there was also an improvement in some heart disease and diabetes risk factors such as blood glucose and insulin levels, blood lipid profiles and blood pressure.

Two groups of dieters were studied. The partial meal replacement (PMR) group replaced 1-2 meals daily with 1-2 vitamin/mineral fortified liquid meal replacements but included at least one meal of regular foods. The reduced calorie diet group (RCD) consumed the same number of calories as the PMR (800-1600kcal/day) but did not consume any meal replacaments. A significantly greater weight loss was achieved in subjects receiving the meal replacements compared with the RCD group. The former lost 7-8% body weight and the latter 3-7% i.e the PMR group lost 2.5kg more. There were also significantly less dropouts in the PMR group after 1 year. No reported adverse events were attributable to either weight loss regimen at one year.

Last Updated: March, 2009.