Generally, in order to shed unwanted weight, we’re told to eat less and move a little more. But could using a meal replacement shake to lose weight be a useful addition to an individual’s weight loss journey?
A meal replacement shake involves very little effort and tends to be either premade or a powder mixed with water or milk. There are a number of reasons why someone may use a meal replacement shake to lose weight, from calorie control through to convenience. However, there are also some drawbacks. Often they may not be filling enough. Plus, for the foodies out there, it can take away the joy of cooking. Because of this, they may cause people to eat more food due to hunger, which could negate the potential weight loss benefits.
Live Science spoke to Liam Holmes, Performance Nutritionist and foodspring (opens in new tab) Ambassador, to determine whether using a meal replacement shake for weight loss is safe or recommended.
How does a meal replacement shake work?
A meal replacement shake is normally a shake that has a balance of protein, carbs and fats with added vitamins and minerals. As the name suggests, these shakes are created to replace a meal, whether that be breakfast, lunch or dinner, or a combination of these.
Holmes explains that meal replacement shakes differ from the best protein powder as they contain a slower digesting form of protein, as well as carbohydrates such as oats, to help you to feel fuller. Since they are replacing a meal, it’s important that a meal replacement shake still fills you up.
“People can find that meal replacement shakes help them to make better choices at meal times,” says Holmes. This is largely due to the fact that there isn’t as much choice when deciding what to make: you simply mix and drink.
“Whereas thinking about breakfast and actually cooking it can be a challenge for some people,” he adds. “Meal replacement shakes are popular with people as they’re just so convenient.”
Does a meal replacement shake work for weight loss?
There are several benefits to meal replacement shakes, making them a useful tool for shedding any unwanted pounds:
May help to control calorie intake
Holmes says that using a meal replacement shake can help with weight loss, as long as the person maintains a calorie deficit over a period of time.
“Being in a calorie deficit is the key driver of weight loss, so if a person swaps a 700 calorie meal for a 400 calorie shake, it could help them to create the deficit needed to elicit weight loss.”
He adds that people could use it to replace a meal where they often overeat or struggle to make good choices, and this will in turn help them to be more consistent.
However, it's important to maintain this calorie deficit. It might be worth tracking calories to stay on top of any extra snacks or food that’s consumed. Research published in Current Nutrition and Food Science (opens in new tab) has also found that swapping a meal or two each day with a meal replacement shake can speed up weight loss.
However, as Holmes explains, a meal replacement shake is not a “magical drink that burns fat and guarantees weight loss”.
“A meal replacement shake can work but only if a person creates a calorie deficit and is consistent with this,” he says.
Ensures protein intake
“Protein is a very important nutrient and when dieting it is essential,” says Holmes. He explains that protein helps to preserve muscle mass when dieting, while also helping people to feel fuller.
“When dieting, managing hunger is a key area that needs attention so having a higher protein intake of around 1.4-1.8g per kg of bodyweight per day, will help. A meal replacement is a convenient way to get adequate protein into your diet.”
There’s also research published in the Nutrition Journal (opens in new tab) to show how a protein-enriched meal replacement can help to increase fat loss. Fat loss and weight loss differ here, as weight loss can include the loss of muscle mass, which is what we want to maintain. Muscle also helps to ensure people have a healthy metabolism, which helps with ongoing calorie burning.
Packs in vitamins and minerals
According to Holmes, when a person is dieting, the fact that calories have to be reduced means there is less opportunity to nourish the body.
“Having a meal replacement with added vitamins and minerals can be a nice way to get some essential nutrients into your diet,” he adds.
In fact, some vitamins and minerals have been proven to actually help with weight maintenance. One study published in Nutrients (opens in new tab) found that whilst vitamin and mineral deficiencies were common among obese individuals, it wasn’t so commonplace in “long-term weight loss maintainers”.
Other research published in the Nutrition Journal (opens in new tab) also found that over a year-long study, those who took meal replacement shakes or bars actually had a more adequate essential nutrient intake than those who ate a traditional food diet.
Using a meal replacement shake for weight loss: Risks & considerations
Amongst the benefits of using a meal replacement shake for weight loss are several negatives. One of these pitfalls is that an individual could become reliant on meal replacement shakes.
“I do think that people can end up using meal replacements for more than one meal or skipping meals and just taking a shake,” says Holmes, who suggests that people use meal replacements sparingly.
“Don’t rely on them for every meal. A good way to use them is for snacks – use half or spit over the morning or afternoon – or to top up the protein content of a meal.”
He also adds that you need to be aware of how you feel after taking a meal replacement shake. “If you feel okay drinking it but are then starving an hour later and end up snacking or overeating in the next meal, then you need to readjust your strategy,” he says.
To stop the hunger that could kick in and potentially disrupt your weight loss efforts, Holmes says that a meal replacement shake could be used alongside a small meal.
“You could have some boiled eggs and a shake, or some yogurt and fruit and a shake for breakfast. This way you get some solid food that doesn’t involve cooking a lot of food.”
There’s also the potential of certain vitamin and mineral deficiencies when taking a meal replacement shake. Although meal replacement shakes tend to contain an array of nutrients needed for good health, they may contain less than wholefoods, or the spectrum of vitamins and minerals may not be suited to the individual.
However, it is worth checking with your GP before embarking on a meal replacement shake diet, to ensure you’re getting the nutrients you need.