Food & Nutrition

Do liquid diets works?

We weigh up whether or not shakes are all it takes to lose weight and achieve long term weight loss success.
Published 21 September 2018

The truth about liquid diets


With a surge in weight-management ‘solutions’, meal replacement systems are everywhere. So what’s in these diet shakes that make them effective for weight loss and do they really work?


Do diet shakes work?

Contrary to popular belief, there is no miracle weight loss cure or proven ingredient lurking within a chocolate-flavoured diet shake. The products are simply a combination of vitamins, minerals and other additives in a flavoured milk- or water-based drink. Recently, we have seen protein shakes take the spot light in this category as a convenience food providing a short term fix for weight loss. They have gained a boom in popularity following high profile celebrities gratifying their benefits however it’s important to note that carefully planned wholesome meals can give the same benefits and may be more sustainable for long term weight loss success. Diet shakes are designed to be partial meal replacements, where one or two meals a day are replaced with the shake and the remaining meals made up of regular food. So there is no magic to unravel with their weight loss success. With a total kilojoule count of only 500-800kJ per meal-replacement drink, shakes exert their effect via kilojoule control. If you ate a couple of small pieces of fruit instead of a couple of meals a day, you would create the same kilojoule deficit. The only difference is that meal-replacement shakes are designed to maintain your nutrition status, while you lose weight. While a few are formulated by government guidelines, with appropriate levels of vitamins, minerals, fibre, omega-3s and more, others are lacking in key nutrients and are not nutritionally complete.


The science behind weight loss shakes

Why do some health professionals prescribe a little shake-up when it was not that long ago meal replacements were seen as a last resort for many dietitians and doctors counselling patients for weight loss? Australia’s rising rate of obesity has put more patients medically at-risk and in need of rapid weight loss before undergoing life-saving surgery. Several clinical studies support that properly formulated meal replacements can be effective for achieving short-term weight loss for people with obesity – in the range of 9-10 per cent of total body weight in the short-term (six to 12 months). Health professionals follow strict screening guidelines and monitoring to minimise patient health risks or complications from rapid weight loss.  


Slow and steady weight loss is best

If you’ve been on the dieting merry-go-round, you want weight loss that lasts. Successful slimmers often say 'slow and steady' wins the race. So before you shake, rattle and roll remember that while some shakes and protein supplements contain filling fibre to help curb hunger, they are a drink, not real food. Unless you can ignore the tastes, sights and smells of your favourite foods you’re likely to feel deprived, and social dates may drop off. Some health professionals are concerned that meal replacements are a temporary fix. Even though there are a lot of celebrity testimonials, on-pack 'guarantees' and persuasive promises, there is a lack of published studies to support many of the brands bursting out of pharmacies.  


The bottom line

While some products are part of broader weight loss programs, taken purely as a diet shake they lack the fundamentals of weight loss success. They do not guide you towards healthier food choices, involve an active lifestyle, provide a supportive environment or promote behavioural change. And once you stop the meal-replacement shakes, many find themselves back at square one and weight regain occurs.