Slim Fast Shake Review: Does it work?

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Expert rating: 2.8/5

Customer rating: stars-icon voted

Intro: What is it?

Slim Fast Shake is a meal replacement that’s widely available and meant to help you control your hunger for up to 4 hours. It’s offered in Creamy Chocolate, Strawberries & Cream, Vanilla Cream, and Caramel Latte.

It’s gluten free and is 99.8% lactose free; according to the bottle it also is clinically proven to help people lose weight. So is this actually true? What kind of benefit is possible if any? Read on to discover the truth about Slim Fast Shake.

Ingredients of Slim Fast Shake

Here are the ingredients for the Vanilla Cream version:

Water Calcium Caseinate Milk Protein Concentrate Canola Oil Maltodextrin
Cellulose Gel Natural Flavor Artificial Flavor Potassium Phosphate Mono and Diglycerides
Potassium Citrate Soy Lecithin Salt Sucralose Carrageenan
Sodium Citrate Citric Acid FD&C Yellow 5 FD&C Yellow 6 Magnesium Phosphate
Sodium Ascorbate Calcium Phosphate Sodium Ascorbate Calcium Phosphate Vitamin E Acetate
Zinc Gluconate Ferric Orthophosphate Manganese Hydrochloride Thiamine Mononitrate Riboflavin
Chromium Chloride Folic Acid Biotin Sodium Molybdate Potassium Iodide
Phylloquinone Sodium Selenite Cyanocobalamin Cholecalciferol

Some of the ingredients aren’t beneficial additives and they’ve been known to cause potential side effects:

FD&C Yellow 5: Food coloring added strictly to make a product look better. It’s one of the most allergen causing of all the food colorings. It can lead to hives and an increase in asthma. Some studies show that it can also lead to ADHD and that it disrupts learning.

FD&C Yellow 6: An extract of petroleum that is used in cosmetics and drugs.  It’s banned in Norway, Sweden, and Finland due to health concerns. There’s no health benefit to adding this ingredient beyond giving the product a more appealing look.

Artificial Flavor: Synthetic ingredient used to mimic the taste of other more wholesome and natural ingredients.  It’s created in a lab and is often used as cheap alternative to all natural ingredients. It’s often not known exactly what went into the making of this additive.

Ferric Orthophosphate: An iron source that is added to processed foods. It’s known as an irritant that can be harmful if swallowed, and it has been shown to lead to skin, eye, and respiratory tract irritations. It’s banned by the European Union since it was deemed unfit for human consumption. Though it has not been banned in the US, there are still red flags raised since published studies have shown these additives are potentially harmful.

None of these ingredients are required; they’re simply cheaper alternatives to all natural additives. They’re either added to provide more minerals, or to make the product look better.

Macronutrients and Calories

Calories 180 Calories from Fat 80 Total Fat 9g, 14% Saturated Fat 1.5g, 8% Cholesterol 10mg, 3%
Sodium 180mg, 8% Potassium 700mg, 20% Carbohydrate 6g, 2% Dietary Fiber 5g, 20% Sugars 1g
Protein 20g, 40% Vitamin A 40% Vitamin C 110% Calcium 40% Iron 15%
Vitamin D 40% Vitamin E 110% Vitamin K 25% Thiamin 40% Riboflavin 40%
Niacin 35% Vitamin B6 30% Folate 35% Vitamin B12 35% Biotin 35%
Pantothenic Acid 35% Phosphorus 45% Iodine 35% Magnesium 35% Zinc 15%
Selenium 20% Manganese 35% Chromium 30%


There’s a significant amount of calories, and a large chunk of it comes from fat. At 180 calories you can expect more effort on your part if you’re looking to lose weight.  It will require you to work harder to burn it off than other lower calorie alternatives.


While 5 grams is a good amount, it’s important to find out where it comes from. The added fiber comes from a mix of ingredients, one of which is something called Cellulose Gel; it’s a processed thickener that’s also used to drill for oil.

A study published by mentioned that his ingredient could lead to:

“Low-grade inflammation” and “obesity/metabolic syndrome”

Another ingredient called Carrageenan is also used to give the shake consistency by thickening it. It has been banned by the European Union over safety concerns.

There have also been multiple studies done which shows it can lead to health problems in mice.  One study also revealed:

Gastrointestinal malignancy and inflammatory bowel disease”

As I’ll go over in the Customer Opinions section, some customers have reported experiencing symptoms similar to what was found in studies on lab mice.  Though Slim Fast Shake provided you with about 20% of your daily fiber per serving, the quality is lacking.

Quality of Slim Fast Shakes protein

There’s a mixture of 2 different protein sources, though since water is the 1st ingredient listed, this means most of it is made up of water instead of protein:

Calcium Caseinate: Slow acting protein source that’s extracted from lower fat milk.  It has been stripped of its vitamins, sugars, and lactose.

Milk Protein Concentrate: Between 40% to 90% protein by volume. It’s often imported from countries like Mexico and China where there are fears that the quality control suffers. The food and water watch organization has expressed concern over the potential for contamination.

Both of these ingredients are somewhat high in protein, but Calcium Caseinate is weak in its lack of minerals. Also there are concerns over the overall safety of Milk Protein Concentrate. It’s not a proper mix of protein and there are much better sources out there for the cost.

These protein sources are not as bioavailable as whey protein as well.

The price and quality of Slim Fast Shake

The price of this can vary wildly depending on where you get it from. I’ve looked over all the available prices on, and an average supply will cost $19.01 for 8 bottles worth.

To get a near a month’s supply you would have to either buy pricier bottles individually, or in bulk by getting 24 at:

$19.01 times 3= 24 bottles at $57.03.

Considering this high price, it would have been better if the company used whey instead of their protein blend. It’s much too costly for what you’re getting. You also have to consider the 180 calories, the fiber sources which have a controversial history, and the use of food colorings and artificial flavors.

Most of the ingredients are actually commonly found in processed foods as a cheaper and less wholesome alternative to all natural ingredients.

When considering meal replacement shakes, it’s important to get high levels of nutrients in order to avoid your body from breaking down. During caloric restrictions the body most needs high levels of nutrition to make up for the lack of calories.

Synthetic Ingredients

Several of the ingredients found inside are lab created and from unnatural sources. There’s added Artificial Flavors, food colorings, as well as a potentially harmful sweetener.

These additives are all added to enhance the product, but they’re really cheap substitutes which can have harmful effects.

Food coloring has been banned in certain countries, Artificial Flavors will often have unknown origins, and the added Sucralose has harmed lab rats.

These additives are best left avoided since the all natural alternatives can provide much more benefits.

The Slim Fat Plan

The company recommends that people take part in their comprehensive plan for optimal weight loss. It’s advised to drink 2 Slim Fast Shakes a day, and to end the day with a 500 calorie dinner.  There are also 3, 100 calorie snacks that are also made by Slim Fast which are recommended.

They offer a few recipe options as well. Though really there’s nothing really unique about the type of foods offered. It’s simply based off a basic reduction of calories which can be done with any kinds of foods.

They claim that Slim Fast offers America’s number #1 weight loss plan. Though this isn’t proven with any real statistics, nor do they offer any before and after photos to help prove these claims.


Slim Fast is operated in Florida and they have been around since 1977. Their main focus has been to sell meal replacement shakes in both powdered and ready to drink forms.

Phone Number: 1-877-375-4632

Address: PO Box 3625
West Palm Beach, FL 33402

They have had some controversies in their history:

  • The company stopped producing Slim Fast after there were fears of contamination. It was never explained what happened and why their manufacturing lead to this outbreak.
  • They have a low ranking on Consumer Affairs. Only 2 out of 5 stars were given to the company due to 33 customer complaints about the quality and overall taste of Slim Fast Shake. Some have criticized the company for offering a pricy meal replacement that has many artificial additives.

Customer Opinions of Slim Fast Shake

You can read many different reviews online from real customers, the most common opinions left on are:

great taste, bad ingredients”

“neutral flavor, not too strong”

“After taste is gross, had to wash my mouth after”

“gave me bad gas and diarrhea”

Though some did like the taste, it’s often reported that there’s a difficult aftertaste that isn’t very pleasant, it’s unknown which of the ingredients is causing this potential effect.  Since some have claimed there’s an artificial sweetness it’s likely from the Sucralose. This sugar source has caused side effects in lab settings.

Other common complaints you’ll often read are from people exclaiming how they felt several different side effects such as stomach issues.  This can be caused from the food coloring, but there’s also other ingredients which may have also been the reason for this effect.


Though widely available, this meal replacement shake has some noticeable flaws:

  • The quality of the protein is severely lacking: There’s 20 grams of protein that come from Milk Protein Concentrate and Calcium Caseinate. Both have their own set of issues. MPC is largely imported from countries where safety standards are not the same. Also, Calcium Caseinate is stripped of its nutrients; this is why companies will have to reintroduce minerals.  Both of these protein sources aren’t as beneficial due to their lower levels of amino acids as other proteins.
  • Processed and Artificial Ingredients are heavily used: In order to make the product more appealing there’s a large mixture of food coloring and Artificial Flavors. This is an unnecessary addition that’s only added because it’s cheaper than all natural ingredients. Money is better spent on avoiding these additives as some of them have been shown to potentially cause unwanted side effects. There’s the possibility for rashes, weight gain, and mood changes. 2 ingredients in this formula have been banned by several European countries over health concerns.
  • Customers have reported side effects: The most common symptoms people face are stomach issues. It’s unknown what the cause of this is, but it’s worth looking into. Some of the additives have been shown to increase the rate of side effects, so it would make sense that some people have reported negative experiences. Customers have also complained about the taste of the product. Some mention it has an artificial taste and that it’s unpleasant to drink.
  • Heavy on the calories and fat: A large chunk of this shake is calories from fat. There’s a total of 180 calories which is considerably more than other meal replacements. Though it’s included as a way to be a filling product, it ends up requiring more exercise on the customers part to help burn it off. Fat also is well retained by the body, so if you get 2 shakes a day you’re getting 160 calories just in fat.
  • Most of the product isn’t protein: The first ingredient listed is water. This means you’re paying for a product which has one of the cheapest ingredients you can find. It would have been better if it was more of a protein base instead. This would ensure you’re getting your money’s worth. The added protein is already lower in amino acids than other sources, so you end up losing even more money this way.

The quality of the ingredients is lacking and there’s a large amount of processed unnatural additives. It’s also expensive when you consider that it’s not as beneficial as other natural meal replacements.

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