Meal replacement shakes are liquid shakes, soups or bars that are designed to be eaten in place of one or two main meals on a daily basis. They are often referred to as ‘nutritionally complete’ which refers to all the component parts of a healthy, balanced diet being included in a particular product.
How effective are Meal replacement shakes?
There is currently no strong evidence to support the assertion that using meal replacement products is either healthier or more effective at helping an individual lose weight than a standard low calorie diet over a prolonged period of time, although there is some evidence that they do play a role in short term weight loss (1).
The evidence base for meal replacement product efficacy has grown quickly over the past decade, with the majority of research carried out in the United States where the product market is the largest. A 2003 study, observing a pharmacy registered population, found there to be no difference in overall weight or waist circumference when comparing the use of a meal replacement product versus a low calorie diet over the course of 5 months (2).
Another observational study observing patterns of weight loss over 2 years between a control group using meal replacement drinks and another group using a low calorie diet found more sustained loss in the group using replacement products. However, the wide range of confounding variables in the study were not accounted for, nor were the large number of participants who dropped out of the study and were not considered in its final results. The study was also financed by a company that produced meal replacement drinks, and the extent of weight loss is likely to be over-exaggerated due to the large number of patients lost to follow up (3).
A study undertaken in 2010, comparing the use of a meal replacement diet plan with a standard diet, found a particular brand of meal replacement drink (Medifast) to increase initial weight loss over a course of 40 weeks in a control group of 90 obese patients in the US. However, there is no evidence to suggest that such weight loss is sustainable in the long term, with the study acknowledging that significantly more weight was regained by its participants over a period of one year after the study (4). Of the 8 listed individuals who co-authored the paper, 6 were salaried employees of Medifast and 2 held stocks and shares in the same company, presenting a conflict of interest that needs to be taken into account when interpreting its findings.
A systematic review of six studies concerned with the safety and efficacy of partial meal replacements, undertaken by researchers at the University of York in 2003, concluded that replacements can result in significant and sustained weight loss over a prolonged period of time < 1 year(5). However, none of the six studies recorded weight or any significant baseline value (such as glucose, triglyceride, cholesterol and blood pressure levels) more than one year after the end of each study, suggesting that any assertions that such supplements can provide significant long term benefits are premature.
A further study, undertaken with a cohort of obese and overweight individuals in Switzerland, found that meal replacement therapies can be an effective way of managing weight over the course of two years as part of a coordinated weight reduction programme. However, it also emphasised that a long-term, sustainable exercise program and low calorie diet was key to maintaining weight loss over the long term rather than a reliance on the prolonged use of meal replacement therapies (6).
Wider data from long term cohort studies regarding the efficacy of diets or meal replacement therapies have found them to result in individuals gaining significantly more weight than they had lost at the beginning of treatment (7).
Systematic reviews of long-term weight loss for replacement therapies often find that evidence regarding long-term loss is inconclusive, suggesting that longer and better designed studies are required to provide more concrete answers (8).
Short-term weight loss
Given their evidence as an effective short-term weight loss option, meal replacements tend to be favoured by individuals who are looking for a quick weight loss ‘fix’. Further support and education is required for individuals after meal replacement supplements have been stopped to encourage longer term healthy eating that is more likely to help with sustained healthy weight.
In conclusion
There is some evidence that meal replacement therapies do assist short-term weight loss. However, many of the studies do not extend beyond a year and other studies have shown longer term weight gain to be significantly higher in all individuals who have previously taken meal replacement therapies for up to one year. Whilst meal replacement therapies may provide a quick and effective method for calorific intake for individuals leading busy lives, tried and tested foods that have proven health benefits such as fruit, granola bars, dry cereal and yogurt will provide the same level of nutrition as replacement supplements and give individuals an increased possibility of maintaining a balanced, healthy weight in the long run.
References
- Rippe JM, Price JM, Hess SA, Kline G, DeMers KA, Damitz S et al. (1998). Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program. Obes.Res 6:208-18
- Ahrens RA, Hower M, Best AM. (2003). Effects of weight reduction interventions by community pharmacists. J Am Pharm Assoc (Wash DC) 43:583-9.
- Rothacker DQ. (2000). Five-year self-management of weight using meal replacements: comparison with matched controls in rural Wisconsin. Nutrition 16:344-8
- Davis LM, Coleman C, Kiel J, Rampolla J et al. (2010). 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 doi: 10.1186/1475-2891-9-11
- Heymsfield SB, van Mierlo CA, van der Knaap HC, Heo M, Frier HI. (2003). Weight management using a meal replacement strategy: meta and pooling analysis from six studies. DARE Available online at http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0020536/ (last accessed 26th March 2015)
- Koohkan S, Schaffner D, Milliron BJ, Frey I. et al. (2014). The impact of a weight reduction program with and without meal-replacement on health related quality of life in middle-aged obese females BMC Women Health 14:45 Available online at http://www.biomedcentral.com/1472-6874/14/45 (last accessed 26th March 2015)
- Blomain ES, Dirhan DA, Valentino MA, Kim GW, Waldman SA. (2013). Mechanisms of weight regain following weight loss. doi: 10.1155/2013/210524. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3901982/ (last accessed 27th March 2015)
- Lopez Barron G, Bacardi Gascon M, De Lira Garcia C, Jimenez Cruz A. (2011). Meal replacement efficacy on long-term weight loss: a systematic review. Nutr Hosp 26(6):1260-5
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