Nothing can split opinion amongst those on a diet more than the weight loss (or to give them their ‘proper’ name, meal replacement) shake.
People often tend to fall into the evangelical, ‘this will change your life’ camp or the dubious, ‘you want me to replace two meals a day with this shit?’ camp.
There is always plenty of noise swirling around the interwebs regarding meal replacement shakes, making it difficult to actually nail down the true facts from the anecdotal ‘it worked for my cousin’s sister’s dog groomer’s best friend’ evidence. We’ve rounded up the evidence from trusted sources to give you the lowdown on how weight loss shakes work, why they work (it’s not magic sadly) and what to look for when choosing one.
Do they work?
The biggie – ‘cos no one wants to be living off a largely liquid diet for the hell of it. The answer? Yes-ish. Meal replacement shakes can work very effectively in the short term but only if you’re committed to using them in exactly the way it was suggested by your chosen program which is usually to replace two meals a day and then enjoy a low-calorie, balanced meal for the third.
The Weight Management Industry of Australia reports that meal replacement products have been shown in clinical trials to produce a weight loss of 3 to 9.5 kg over one to five years. They caution however that they are not a substitute for your entire daily food intake and should be used in conjunction with a healthy, balanced diet and regular exercise.
In other words, they are not a magic pill. They can help you lose a substantial amount of weight but to do so, you really do not to commit and work on building new habits for the long term.
Why do they work?
The science behind why meal replacement shakes and other products work is not complicated. Typically, your standard meal replacement shake will be extremely low in calories (usually between 800kj-900kj per serve). If you are replacing your typical breakfast and lunch with a weight loss shake, your overall calorie intake will be dramatically reduced. Experts generally recommend that to lose weight steadily, women should consume around 1200 calories per day. Weight loss shakes make it very easy (in theory) to stick to this number of calories without the need for meal planning or prepping. In short, they help you eat less and consume fewer calories. In conjunction with a third, healthy meal each day and moderate exercise, you will be able to achieve a reasonable calorie deficit which means you are using more energy than you are consuming.
The downside? Less calories means that your tummy may spend a lot more time rumbling, especially in the early days. If you are used to consuming more than 1200 calories (which many of us are), cutting right back can come as a shock to the system and leave you more prone to snacking or really going hell for leather during your non-shake meal each day.
The Canstar Blue survey of dieting Aussies found that 64% of those surveyed ended up snacking between meals after not feeling satisfied post shake which goes some way in explaining why less than 60% of respondents reported successfully losing weight while using meal replacement shakes. The moral of the story? You need to find a product and/or brand that leaves you feeling relatively full and satisfied.
What to look for when choosing a Meal Replacement product
There is no shortage of options when it comes to weight loss shakes. The market is absolutely saturated with products, all making slightly different claims but with the same end result — weight loss. The majority of products are made with skim milk powder and are high in protein and fibre and very low in fat. Many also contain ingredients like wheat and soy which is worth noting for those who may be sensitive or intolerant.
One of the most important things to note when choosing a product is the sugar content. Canstar found that some products can contain up to 23g of sugar per serve (almost 6 teaspoons!) while others contained less than 2g. The type of sugar it used is also important. Fructose, xylitol, stevia and a variety of artificial sweeteners are the most commonly used to ensure the shake tastes good. Clearly, avoiding products with an excess of sugar is going to be your best bet for sustained weight loss.
There are also a number of more ‘natural’ products hitting the market which are free from artificial sweeteners and use largely whole, organic ingredients. The downside to these products is the cost, sometimes more than double your typical supermarket brand.