Liquid diet for weight loss: Does it work and is it safe?

Unless you've gone off the grid, you've probably been exposed to a bunch of them — influencer ads peddling weight loss shakes, and liquid meal products.

There are new brands popping up every day, making it hard to tell what's legit and what isn't. Just because it comes with a cute hoodie or drink bottle, doesn't mean we need it in our bodies!

While we all want to look as hot as our favourite celebs, can we really trust them to be giving diet advice?

Before you click on the latest sponsored Insta post, let's have a closer look at some of these trends. In this article, we'll explore liquid diets, how safe they are, and other weight loss alternatives if that's your goal.

What is a liquid diet?

A liquid diet refers to following a diet plan where you only consume liquids or foods that become liquid at room temperature (like ice cream).

You might have heard of a liquid diet if you've had certain surgeries or had to get ready for a medical procedure — like a colonoscopy or surgery on your stomach/intestines [1].

But what actually counts as a liquid diet?

If you've been asked to follow a liquid diet, some of the things medical professionals say can be included are:

• Icy poles or popsicles
• Plain ice cream or frozen yoghurt
• Water
• Soups and broths (like bone broth, chicken broth, and strained creamy soups)
• Jelly, custard, and pudding
• Fruit or vegetable juices
• Tea or coffee (with milk, sugar and/or honey if needed)
• Greek yoghurt
• Butter/margarine, oils, and cream
• Soft drinks (like Sprite or ginger ale)
• Protein shakes and meal replacement shakes (which should be discussed with your doctor [1]).

Things that don't count as being part of a liquid diet include: mashed potatoes, mashed avocado (sorry avo toast lovers!), cheese, fruit, meat, raw or cooked vegetables, or cereals.

You should also look out for any yoghurts or ice creams that have add-ons like nuts, choc chips, or cookie pieces (these aren't approved for liquid diets) [1].

If you're on a medical liquid diet and unsure about something you can/can't eat, it's always best to check in with your doctor or dietitian. They can give you advice on how to mix and match from the approved 'liquid diet foods' list — to make sure you're getting the right amount of calories, protein, energy and fat.

Types of liquid diets

Full liquid diets sound kind of self-explanatory, but they're actually more complex than you might think (just look at the rules above). And did we mention there are different kinds of liquid diets?

The one we've just mentioned is what's called a full liquid diet. But there's actually more than one type of liquid diet out there — let's check out the rest.

Clear liquid diets

A clear liquid diet is pretty much what it sounds like — it's made up of clear liquids and foods, or foods that become clear at room temperature.

The list of things you're allowed to consume on a clear liquid diet is a bit stricter, but it includes plain water, fruit juices or vegetable juices without pulp, clear broths, clear soft drinks (like Sprite), sports drinks without colour, tea or coffee with no milk, and clear icy poles that don't have fruit juice/pulp in them [2].

The clear liquid diet should only be done under medical supervision or as part of a medical procedure — this isn't a diet for losing weight.

Healthy people shouldn't be on a clear liquid diet for more than 3 to 4 days [2].

Liquid meal replacement diets

A liquid meal replacement diet is one you've probably seen more often. These diets use meal replacement shakes in place of solid food, to help people consume fewer calories. Think of the shakes in TV ads or in your local pharmacy [3].

People often use liquid meals or meal replacements by swapping them out for their normal diet once or twice a day.

Although meal replacement shakes can be a great tool if you're struggling not to overeat, it's important to know that they don't contain all the essential nutrients you need in a day, so should never be used as your only food source or replace a balanced diet.

It's also really important to seek advice from your doctor or dietitian before making any substantial changes to your diet [3].

Mechanical soft diets and dysphagia diets

The last kind of liquid diets you may come across are mechanical soft diets or dysphagia diets. These are medically advised liquid diets for people who are having trouble chewing or swallowing or have recently had surgery on their mouth, throat, or jaw [4].

These diets focus more on soft foods (like mashed potatoes, blended foods or purees, soft-boiled eggs, etc.) but can also include liquids.

They might also involve a slow transition back to solid foods as you recover. Again, these diets aren't recommended for weight loss — they're only appropriate if medically necessary [4].

Do liquid diets work for weight loss?

Let's be very clear — it's possible to lose body weight on a liquid diet, but it's not the best (or healthiest) way to go about it. Most of the studies of liquid diets for weight loss have been conducted on diabetic people, who were all under strict medical supervision [5].

These studies showed that even though a liquid diet might lead to rapid weight loss, most people experienced weight gain again later on.

There was also little evidence to suggest that liquid diets led to significant changes in body fat or waist circumference [5].

Liquid diets or liquid meal replacement diets might be recommended by a doctor in certain situations —  like for people with diabetes, who need extra measures to regulate their blood sugar or for weight management.

It definitely shouldn't be used as a go-to for weight loss, or without the right guidance from a doctor or registered dietitian [5].

Pros and cons of a liquid diet

So, is a liquid diet healthy? Or a fad you should steer clear of?

In case you need a bit more info, here are some of the pros and cons of following a liquid diet. Spoiler alert: the cons list is longer.

Pros

• Can give your digestive system a break, particularly if you have certain medical conditions
• Can help you heal from jaw or mouth problems
• Might help you get some nutrients down if you're recovering from an illness
• Can aid weight loss in certain circumstances (under medical supervision) [1][2]

Cons

• Can cause nutrient deficiencies, meaning you don't get the vitamins and minerals your body needs
• Doesn't contain enough fibre, which can cause side effects such as constipation or diarrhoea
• Might cause fatigue, irritability or feeling unwell [1][2]
• Can lead to loss of muscle and a slower metabolism, making weight loss harder in the long run
• Can affect how certain medications work
• In some cases, can lead to increased thirst and dehydration
• Can lead to low mood and dissatisfaction, due to not being able to enjoy regular solid food [7]

How to lose weight sustainably

Here's the thing — losing weight isn't usually the difficult part, but maintaining weight loss can be.

By now it's pretty clear that liquid diets aren't going to create sustainable weight loss. Once you start to eat solid foods again and go back to your usual lifestyle, it's very easy to gain weight back [6].

So what's the best way to achieve sustainable weight loss? It's not detox diets, drastic eating habits or that new diet program everyone is posting about. The real key is making small, achievable changes to your diet and exercise habits that are easy to stick to [6].

This could look like making sure your daily calories (or energy intake) match the amount of energy/calories you're using in a day. Maybe it's time to introduce some more gentle exercise where you can [6].

It's also really important to keep eating a balanced diet, especially fruit and vegetables — which help you feel full for longer.

Other small changes like swapping soft drinks for water, reducing alcohol intake, watching things like salt, sugar and fat, eating regularly, avoiding snacking, and being mindful of portions can all make a huge difference [6].

When it comes to exercise, take it slow at first and find ways to be active you actually enjoy. Why slog it out for hours on a treadmill when you could go for a walk or do some gardening (if that's your thing)? Parking further away at the shops, taking the stairs instead of the lift, and walking the dog (or borrowing someone else's dog!) can all help burn calories and promote weight loss [6].

If you've tried every strategy under the sun and still feel like you're getting nowhere, it can be great to get some professional advice.

Juniper's Weight Reset Program can help give you the kickstart you need. Get treatment that targets weight gain on a biological level, plus a dietitian-led program that supports long-term weight maintenance.

Our team of dietitians, nutritionists, and health experts can support you to reach your weight loss goals and make changes that fit your specific needs.

When you're trying to lose weight, everything can feel like a punishment or obstacle. That's why it's important to do your research, and set goals that suit you — not the latest TikTok trend.

Be kind to yourself, wherever you're at. You deserve a loving relationship with your body.

Image credit: Getty Images