The Best Weight Loss Shakes - 2025 Options
Our guide explains everything you need to know about weight loss shakes, what to look for and which to choose for your weight loss goals. We compare Optifast, FastFx, Naturally Slim Powder (by Healtheries), Horleys Sculpt, Celebrity Slim and IsaLean Shake (by Isagenix)
Updated 3 April 2025
Know This First: When buying any weight loss shakes, it's essential to look at the nutritional information on the packaging. Often, weight loss shakes are marketed as low fat and end up adding hidden sugars that can increase your calories.
Our guide covers:
Know This First: When buying any weight loss shakes, it's essential to look at the nutritional information on the packaging. Often, weight loss shakes are marketed as low fat and end up adding hidden sugars that can increase your calories.
Our guide covers:
- What are Weight-Loss Shakes, and How Do They Work?
- Calorie Intake Goal - How to Make Calorie Calculations, and What Should the Deficit Be?
- Weight-loss Shakes: Pros and Cons
- Top Weight Loss Shakes: Optifast vs FastFx vs Naturally Slim Powder (by Healtheries) vs Horleys Sculpt vs Celebrity Slim vs IsaLean Shake (by Isagenix)
What are Weight-Loss Shakes, and How Do They Work?
Weight loss shakes are also known as meal replacement shakes. They're an alternative way to incorporate nutrition into your body if you lack time to prepare a healthy meal or are looking to lose some weight. Weight loss shakes are designed to help with weight control by reducing the number of carbs and sugar consumed while still providing other essential nutrients such as vitamins and antioxidants. In addition, given that most weight loss shakes are protein-based, they can help support your normal healthy metabolism and reduce your appetite.
Most weight loss shakes contain 200 - 400 calories per serving and provide a good amount of protein, fibre and essential vitamins. The ingredients and nutrient composition can vary, of course, depending on the brand you buy. Some weight loss shakes are pre-made, making it convenient to bring around as a single serving bottle. Other shakes come as a powder that you can mix with milk or water.
Most weight loss shakes contain 200 - 400 calories per serving and provide a good amount of protein, fibre and essential vitamins. The ingredients and nutrient composition can vary, of course, depending on the brand you buy. Some weight loss shakes are pre-made, making it convenient to bring around as a single serving bottle. Other shakes come as a powder that you can mix with milk or water.
Calorie Intake Goal - How to Make Calorie Calculations, and What Should the Deficit Be?
Nutrition for weight loss is about three things: appetite management, calorie control and healthy snacking. For calorie control, the most simple thing to look out for is calorie intake: the number of calories you consume should be less than the number of calories you burn. This creates a calorie deficit. For most people, having a deficit of 500 calories is sufficient to enter a weight-loss state. To know how many calories to consume, it's important to know where your calories come from and where they're being spent.
This may require you to do some calorie calculations. To get started:
Example: If your total calorie expenditure is 3000 calories in a day, your goal would be to create a deficit of 500 and consume 2500 calories.
Important to note:
This may require you to do some calorie calculations. To get started:
- Know your base metabolic rate - this represents the number of calories your body burns at its resting state
- Add the calories your body consumes throughout the day and note down all physical activity you perform
- Total will equal the number of calories you must consume on a given day to maintain your weight (also known as total calorie expenditure)
- Your initial goal will be to create a deficit by subtracting about 500 calories from that calculated total expenditure
Example: If your total calorie expenditure is 3000 calories in a day, your goal would be to create a deficit of 500 and consume 2500 calories.
Important to note:
- Introducing a deficit to your calorie intake should be done slowly, not abruptly. That way, your body will be prepared to handle the deficit.
- Make sure to consult a professional (such as a nutritionist, dietitian or doctor) if needed.
- Do not consume less than 1,200 calories - this may potentially be harmful to some people as basic nutrients would be lacking for the proper functioning of the body.
Weight-loss Shakes: Pros and Cons
Weight loss shakes come with many advantages, but it's always good to look at the downsides to help you make a more informed decision. Losing weight isn't ever easy, especially when it requires certain lifestyle and habit changes.
Pros of weight loss shakes:
- It helps you consume all the nutrients you need in your diet - weight loss shakes are designed to work as a full meal. When you go on diets to cut back on calories, it can be difficult to obtain all the nutrients your body needs. These include calcium, potassium, iron, vitamin C, vitamin D and many more. In addition, weight loss shakes are often high in fibre which helps with digestion, so you don't feel bloated or have constipation. Using weight loss shakes in conjunction with nutrient-packed, low-calorie snacks like a fruit salad or serving of brown rice can help you fill that nutrient gap.
- Help you avoid unhealthy meals - one of the biggest barriers to losing weight is taking time out to prepare healthy meals. Often, it's much easier to grab some processed food from the supermarket or give in to fast food options. Processed foods are high in sugar, salt and fat, which can derail your weight loss efforts by a lot. With most weight loss shakes being portable and convenient, it helps you resist indulging in unhealthy foods.
- Weight loss shakes can decrease hunger and appetite - as outlined above, many weight loss shakes are high in protein, which generally helps your body feel satisfied for longer than other macronutrients. This is partly due to the release of satiety hormones GLP-1 and PYY that play a role in the sensations of fullness.
Cons of weight loss shakes:
- Some weight loss shakes may contain unnecessary added sugar, especially ones that taste like milkshakes, and may have extra sugar lurking behind the packaging. When deciding what weight loss shakes to choose, aim for an option that contains less than 10 grams of sugar per serving.
The reason is that many weight loss shakes are marketed as low fat. Fat has an inherent flavour, so for the product to taste nice, the easiest way to add flavour is by cranking up the sugar. But, once sugar is digested, the excess stored in your body becomes fat.
If you have serious sugar cravings, consider adding some pre-prepared snacks to your weight loss shakes or add a handful of low sugar fruit like mixed berries or add coconut, almond or hazelnut milk. As you see, there are so many delicious ways to get healthy and achieve your weight loss goal. Choosing a sugar-free or low sugar option doesn't mean you have to sacrifice taste. - It May not be a long term solution.
Most people don't live on weight loss shakes forever. Usually, these last for no more than a few months. That's because it takes the fun and pleasure out of eating. However, for people on weight loss shakes, it can leave them with a dieting mentality by seeing foods as good or bad and feeling guilty for eating "bad" foods - which often can lead to a cycle of restricting food, bingeing and then restricting again. Furthermore, it can be a socially isolating practice since many social events include food. - They don't change habits.
While drinking weight loss shakes can help lose weight, they don't force people to change their unhealthy eating habits. Long term weight loss requires a long term lifestyle change. That's why diets generally don't work. After the diet ends, you simply go back to your old eating habits and regain that weight back again.
Top Weight Loss Shakes - Our In-Depth Comparison: Optifast vs FastFx vs Naturally Slim Powder (by Healtheries) vs Horleys Sculpt vs Celebrity Slim vs IsaLean Shake (by Isagenix)
Just as everyone has different nutritional needs, not all weight loss shakes are created equal. When determining which weight-loss shake to choose, it's important to look at ingredient quality, nutrient ratio, dietary requirements and price.
Optifast
More details: Optifast
Optifast is one of the most well-known brands when it comes to effective weight loss. They are also one of the few medically supervised weight loss programs shown to work with studies that show effectiveness in achieving weight loss. Optifast offers a range of products from bars, shakes and soups. Its intensive VLCD (Very Low-Calorie Diet) program is a nutritionally complete diet regimen with the weight loss averaging approximately 1.2 - 2.5kg per week, providing greater initial weight loss than other forms of calorie restriction. This varies between individuals and depends on how much and what type of other foods are being eaten and the amount and intensity of physical exercise.
Optifast ingredients include:
Nutrition information for Optifast's chocolate-flavoured shake per serving:
Optifast is one of the most well-known brands when it comes to effective weight loss. They are also one of the few medically supervised weight loss programs shown to work with studies that show effectiveness in achieving weight loss. Optifast offers a range of products from bars, shakes and soups. Its intensive VLCD (Very Low-Calorie Diet) program is a nutritionally complete diet regimen with the weight loss averaging approximately 1.2 - 2.5kg per week, providing greater initial weight loss than other forms of calorie restriction. This varies between individuals and depends on how much and what type of other foods are being eaten and the amount and intensity of physical exercise.
Optifast ingredients include:
- Milk protein concentrate - this aids weight loss by boosting metabolism and reducing appetite. However, one downside is poor solubility; if it is not properly dissolved, the powder can leave a grainy feeling in the mouth.
- Soy protein isolate - a good source of high-quality protein and healthful fat. Soy has also been shown to help with mood and skin health.
- Maltodextrin - This is added as a source of fibre or as a prebiotic
Nutrition information for Optifast's chocolate-flavoured shake per serving:
Calories |
201 |
Protein |
20 grams |
Fat |
4.5 grams |
Carbs |
18.2 grams |
Sugars |
9.5 grams |
Dietary Fiber |
3.6 grams |
Servings per pack: 12
Serving size: 53g (powder)
Price: $48 (depends on where the product is bought)
Price per serving: $4
Available flavours: chocolate, vanilla, strawberry, caramel, coffee, mocha, banana and chai
Dietary requirements: vegetarian friendly and gluten free
More details: Optifast
Serving size: 53g (powder)
Price: $48 (depends on where the product is bought)
Price per serving: $4
Available flavours: chocolate, vanilla, strawberry, caramel, coffee, mocha, banana and chai
Dietary requirements: vegetarian friendly and gluten free
More details: Optifast
FastFx
More details: FastFx
All products of FastFx are carefully designed, using only ingredients of the highest quality. Designed and made in New Zealand by gastroenterologists and dietitians, their formula contains 21 organic vitamins and minerals from fruit and vegetables. Additionally, all of their products are certified non-GMO ingredients.
What's great is that they utilise plant-based proteins that contain high levels of amino acids, fibre, vitamins and minerals.
FastFx ingredients include:
Nutrition information for FastFx's vanilla shake per serving:
All products of FastFx are carefully designed, using only ingredients of the highest quality. Designed and made in New Zealand by gastroenterologists and dietitians, their formula contains 21 organic vitamins and minerals from fruit and vegetables. Additionally, all of their products are certified non-GMO ingredients.
What's great is that they utilise plant-based proteins that contain high levels of amino acids, fibre, vitamins and minerals.
FastFx ingredients include:
- Pea protein isolate - high source of protein that is naturally vegan, hypoallergenic and a great source of iron
- Isomaltulose - a better alternative to common sugars found naturally in small quantities in honey and sugar cane juice
- Inulin - prebiotic fibre that helps boost gut health and improves the regularity of digestion
Nutrition information for FastFx's vanilla shake per serving:
Calories |
204 |
Protein |
27.4 grams |
Fat |
0.4 grams |
Carbs |
16.4 grams |
Sugars |
13.9 grams |
Dietary Fiber |
5.5 grams |
Servings per pack: 20
Serving size: 250ml
Price: $85 (depends on where the product is bought)
Price per serving: $4.25
Available flavours: vanilla, salted caramel, chocolate, green apple, spiced chai and mixed berry (All contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: FastFx
Serving size: 250ml
Price: $85 (depends on where the product is bought)
Price per serving: $4.25
Available flavours: vanilla, salted caramel, chocolate, green apple, spiced chai and mixed berry (All contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: FastFx
Naturally Slim Powder (by Healtheries)
More details: Naturally Slim Powder (by Healtheries)
If you've been to any natural health stores in New Zealand, you've probably seen Healtheries. Healtheries is a trusted NZ brand for vitamins and supplements with a strong focus on overall health and wellness. Their weight loss shakes are no exception. Healtheries's Naturally Slim Powders have a 5-star health rating that come with high protein and fibre content as well as 15 vitamins and minerals to help support a healthy lifestyle.
Healtheries ingredients include:
Nutrition information for Naturally Slim Powder per serving:
If you've been to any natural health stores in New Zealand, you've probably seen Healtheries. Healtheries is a trusted NZ brand for vitamins and supplements with a strong focus on overall health and wellness. Their weight loss shakes are no exception. Healtheries's Naturally Slim Powders have a 5-star health rating that come with high protein and fibre content as well as 15 vitamins and minerals to help support a healthy lifestyle.
Healtheries ingredients include:
- Whey protein concentrate - taking whey protein is a great way to increase protein intake while optimising overall health, such as lowering high cholesterol.
- Prebiotic corn fibre - helps feed the beneficial bacteria in your gut to improve overall gut health.
- Niacin - This is a source of B vitamins used by your body to turn food into energy. This helps keep your nervous system, digestive system and skin healthy.
Nutrition information for Naturally Slim Powder per serving:
Calories |
100 |
Protein |
13.1 grams |
Fat |
1.9 grams |
Carbs |
6.0 grams |
Sugars |
5.4 grams |
Dietary Fiber |
2.5 grams |
Servings per pack: 19
Serving size: 250ml
Price: $24.99 (depends on where the product is bought)
Price per serving: $1.32
Available flavours: tropical, vanilla, chocolate and berry (All contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: Naturally Slim Powder (by Healtheries)
Serving size: 250ml
Price: $24.99 (depends on where the product is bought)
Price per serving: $1.32
Available flavours: tropical, vanilla, chocolate and berry (All contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: Naturally Slim Powder (by Healtheries)
Horleys Sculpt
More details: Horleys Sculpt
When people hear about Horleys, they think about sport, fitness and health. Being a customer-centric company, they focus on creating products that cater for diverse usage occasions, goals and budgets. All Horleys products are based on credible scientific research and established sports nutrition practices worldwide.
For weight loss, Horleys Sculpt provides you with high protein meal and snack options to help manage appetite, assist (along with regular exercise) with muscle tone and fat loss, and stave off unhealthy cravings. In addition, Sculpt can be used as an occasional nutritious and convenient meal replacement if you're actively managing your weight. Other weight loss options that can be looked at include Horleys Carb Less Protein bars and Protein Hit Low Carb Drink which are portable and convenient.
Horleys Sculpt ingredients include:
Nutrition information for Horleys Sculpt per serving:
When people hear about Horleys, they think about sport, fitness and health. Being a customer-centric company, they focus on creating products that cater for diverse usage occasions, goals and budgets. All Horleys products are based on credible scientific research and established sports nutrition practices worldwide.
For weight loss, Horleys Sculpt provides you with high protein meal and snack options to help manage appetite, assist (along with regular exercise) with muscle tone and fat loss, and stave off unhealthy cravings. In addition, Sculpt can be used as an occasional nutritious and convenient meal replacement if you're actively managing your weight. Other weight loss options that can be looked at include Horleys Carb Less Protein bars and Protein Hit Low Carb Drink which are portable and convenient.
Horleys Sculpt ingredients include:
- Whey protein concentrate and soy protein concentrate/isolate - a source of protein using pure NZ whey protein and non-GMO soy
- Garcinia Cambogia extract (also known as Super CitriMax) - blocks the body's ability to make fat and puts the brakes on your appetite by raising the levels of the brain chemical serotonin.
- Inulin - prebiotic fibre that helps boost gut health and improves the regularity of digestion
- L-carnitine - allows the cells in your body to break down fat and get energy from stored fat reserves.
- Green tea extract - rich in antioxidants and increases fat metabolism
Nutrition information for Horleys Sculpt per serving:
Calories |
96 |
Protein |
18.7 grams |
Fat |
1.1 grams |
Carbs |
2.0 grams |
Sugars |
1.4 grams |
Dietary Fiber |
1.0 grams |
Servings per pack: 20
Serving size: 250ml
Price: $30 (depends on where the product is bought)
Price per serving: $1.50
Available flavours: milk chocolate, vanilla cream, berry yoghurt, banana smoothie and salted caramel (all flavours contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: Horleys Sculpt
Serving size: 250ml
Price: $30 (depends on where the product is bought)
Price per serving: $1.50
Available flavours: milk chocolate, vanilla cream, berry yoghurt, banana smoothie and salted caramel (all flavours contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: Horleys Sculpt
Celebrity Slim
More details: Celebrity Slim
Developed by expert nutritionists and biochemists, Celebrity Slim is perhaps one of the best-tasting weight loss shakes out there. Instead of offering just one standard weight-loss shake, Celebrity Slim offers several weight loss shakes that suit various stages of the Celebrity Slim weight loss program and many dietary requirements. These include Celebrity Slim's Dairy and Gluten-free shakes, Rapid Low Sugar Shakes, Meal Replacement Shakes and Low Carb Shakes.
The Celebrity Slim program is designed in three stages:
Celebrity Slim ingredients include:
Nutrition information for Celebrity Slim per serving:
Developed by expert nutritionists and biochemists, Celebrity Slim is perhaps one of the best-tasting weight loss shakes out there. Instead of offering just one standard weight-loss shake, Celebrity Slim offers several weight loss shakes that suit various stages of the Celebrity Slim weight loss program and many dietary requirements. These include Celebrity Slim's Dairy and Gluten-free shakes, Rapid Low Sugar Shakes, Meal Replacement Shakes and Low Carb Shakes.
The Celebrity Slim program is designed in three stages:
- Rapid phase: kickstart your weight loss and get the ball rolling
- Trim phase: reach your weight loss goal - intended for sustainable weight loss long-term
- Maintain phase: maintain your weight loss - intended for people who have reached their goal or require additional assistance to improve their health.
Celebrity Slim ingredients include:
- Whey protein concentrate and soy protein isolate - high source of protein. Soy protein contains specific plant nutrients known as isoflavones that help regulate many body processes to balance hormone and energy systems.
- Caseinate - a dairy protein rich in amino acids, provides you with a feeling of fullness to help control your appetite.
- Green tea extract - rich in antioxidants and increases fat metabolism
- BioFibre - increases satiety (fullness)
Nutrition information for Celebrity Slim per serving:
Calories |
212 |
Protein |
18.9 grams |
Fat |
2.4 grams |
Carbs |
27.4 grams |
Sugars |
24.6 grams |
Dietary Fiber |
1.2 grams |
Servings per pack: 10
Serving size: 55 grams
Price: $51.00 (depends on where the product is bought)
Price per serving: $5.50
Available flavours: chocolate, strawberry, banana, cafe latte, vanilla (all flavours contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: Celebrity Slim
Serving size: 55 grams
Price: $51.00 (depends on where the product is bought)
Price per serving: $5.50
Available flavours: chocolate, strawberry, banana, cafe latte, vanilla (all flavours contain MILK and SOY)
Dietary requirements: vegetarian friendly and gluten free
More details: Celebrity Slim
IsaLean Shake (by Isagenix)
More details: IsaLean Shake (by Isagenix)
IsaLean shakes are unique because they contain superior nutrition compared to other meal replacement shakes on the market. In addition, they contain exclusively sourced Myo-IsaLean Complex: high-quality whey protein from pasture-raised cows that are not treated with hormones or routine antibiotics.
Isagenix has an independent QRTS department (QRTS stands for Quality, Regulatory, Technology and Science) that ensures their products are science-backed and constantly tested in laboratories and clinical studies.
IsaLean Shake ingredients include:
Nutrition information for IsaLean Shake per serving:
IsaLean shakes are unique because they contain superior nutrition compared to other meal replacement shakes on the market. In addition, they contain exclusively sourced Myo-IsaLean Complex: high-quality whey protein from pasture-raised cows that are not treated with hormones or routine antibiotics.
Isagenix has an independent QRTS department (QRTS stands for Quality, Regulatory, Technology and Science) that ensures their products are science-backed and constantly tested in laboratories and clinical studies.
IsaLean Shake ingredients include:
- Whey protein concentrate (undenatured) - effective for low-calorie diets and modestly limiting fat gain during periods of excessive calorie intake
- Digestion-resistant maltodextrin - a common high-glycemic carbohydrate used in protein shakes
- Medicago sativa (also known as Ionic Alfalfa) is a low-calorie, nutrient-dense food that helps reduce cholesterol and aids in weight loss by increasing satiety.
- Lactobacillus acidophilus is a probiotic bacteria that naturally occurs in the human gut and other body parts. This helps the digestive system break down sugars.
Nutrition information for IsaLean Shake per serving:
Calories |
212 |
Protein |
24 grams |
Fat |
5 grams |
Carbs |
24 grams |
Sugars |
11 grams |
Dietary Fiber |
8 grams |
Servings per pack: 14
Serving size: 60 grams (2 scoops)
Price: $107 (as a one-off, and cheaper with a subscription)
Price per serving: $7.64
Available flavours: creamy french vanilla, creamy dutch chocolate, strawberry cream and chocolate mint (all flavours contain MILK and SOY)
Dietary requirements: vegetarian friendly, soy-free, low-glycemic and gluten-free
More details: IsaLean Shake (by Isagenix)
Serving size: 60 grams (2 scoops)
Price: $107 (as a one-off, and cheaper with a subscription)
Price per serving: $7.64
Available flavours: creamy french vanilla, creamy dutch chocolate, strawberry cream and chocolate mint (all flavours contain MILK and SOY)
Dietary requirements: vegetarian friendly, soy-free, low-glycemic and gluten-free
More details: IsaLean Shake (by Isagenix)
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