SlimFast Reviews 2023: Does It Work For Weight Loss?

Reviewed by Kathy Shattler, MS, RDN

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  • = Quality
  • = Brand’s Transparency
  • = Value

  • Simple instructions to follow for meal replacement shakes
  • Low-calorie meal replacement products
  • Contains different vital minerals and vitamins
  • Effective for short-term weight loss
  • Naturally flavored meal replacement bars
  • Ideal for adding to meal planning
  • Creamy and tasty shake mix
  • Reputable company 
  • Provides clear details of ingredients
  • Products have a good taste
  • Good for advanced nutrition
  • Regulates blood sugar content
  • Good for weight loss

About The Brand

SlimFast is a popular weight loss plan that’s been around for decades. Since 1977, SlimFast has been a much sought-after meal replacement diet plan for people who want to lose weight. Initially, users had to take two meal replacement shakes and a healthy meal each day.

But, as time changes, the company has added different SlimFast meal replacement products. Now, you can find snacks, shakes, bars, and smoothies from SlimFast. Products from the company vary from Keto Formulations, Original, Diabetic Weight Loss, Advanced Nutrition, and Advanced Energy.

A 1-2-3 plan guides the upgraded SlimFast partial meal replacement plan. You can take one sensible meal, two meal replacements, and three snacks each day you follow the diet plan. You’re also free to pick from 4 different versions: Low-Carbohydrate (carb), Original, Keto, and Favorite Food. Reading through SlimFast diet reviews shows the products are good for weight loss.

Does SlimFast Work?

Is SlimFast effective for weight loss? This is one of the biggest concerns people have when they come across a diet plan. Will having one sensible meal, two meal replacements, and three snacks be the key to losing weight?

If you consider the total calorie intake, you just might end up attaining your weight loss goals. This is because you get to consume only 1200 calories per day. Many people need about 2,000 calories to maintain their weight on a normal day. So this means using the SlimFast meal replacement plan, you have a deficit of 800 calories[1].

As good as this may sound, maintaining the SlimFast diet plan long-term[2] may be an unobtainable challenge. Maintaining this way of life for a long time is difficult to achieve sustainable weight loss. This is why SlimFast and other similar commercial weight loss programs[3] may only be ideal for short-term weight loss.

A recent study[4] showed that meal replacement programs are effective for weight loss. However, the results would be so much more effective when mixed with behavioral changes and program support. This means improving self-efficacy, going for therapy, practicing portion control and developing better food relationships.

Top SlimFast Products In (March. 2023)

SlimFast Original Shake Mixes
SlimFast Original Shake Mixes
  • Comes in a delicious chocolate flavor
  • Creamy and tasty shake mix
  • Contains 26 different minerals and vitamins

SlimFast Intermittent Fasting Complete Meal Bars
SlimFast Intermittent Fasting Complete Meal Bars
  • Comes in two different flavors
  • Naturally flavored meal replacement bars
  • Contains 15 grams of protein and 10 grams fiber

SlimFast Keto Fat Bomb Snack Cups
SlimFast Keto Fat Bomb Snack Cups
  • Perfect Keto snacks for weight loss
  • Low-carbohydrate meal replacement product
  • No added sugar

SlimFast Advanced Nutrition Shakes
SlimFast Advanced Nutrition Shakes
  • High protein meal replacement shakes
  • Contain 20 grams of drinkable protein
  • Has only one gram of sugar per serving

Who Is SlimFast For?

SlimFast Meal Replacement products are perfect for folks who want to achieve their weight loss goals. The good news is these are low-calorie products that are simple to mix and consume. These products are great for a busy lifestyle, but you still want to focus on healthy eating and being physically active. There are no cumbersome rules that govern a SlimFast diet plan. Everything is straightforward, and the ingredients are clearly detailed on each product. There are many minerals and vitamins in each SlimFast product that benefit your health and well-being.


  • Simple instructions to follow for meal replacement shakes
  • Low-calorie meal replacement products
  • Perfect for a busy lifestyle


  • Highly-priced meal replacement products
  • Can be a bit restrictive
  • Reliance on highly processed ingredients
  • May not be ideal for long-term weight loss

Best-Sellers Products Of Nutricode In 2023

Original Shake Mixes

SlimFast Original Shake Mixes

SlimFast Original Shake Mixes is the perfect example of a meal replacement product. A whole host of ingredients in the shake mix include sugar, cocoa, milk protein concentrate, buttermilk powder, gum arabic, soy lecithin, soy fiber.

  • Creamy, and tasty shake mix
  • Contains 26 different minerals and vitamins as well as four grams of fiber
  • Good for meal substitution when you want to lose weight
  • Contains a significant amount of sugar and other artificial sweeteners

One of the best SlimFast products to take when you want to lose weight is the SlimFast milk replacement shake mix. This is a diet-friendly shake you can take on your weight loss journey.

You can take this gluten-free product as you consider other calorie restrictions. The product has two grams of protein, but you can add protein content by mixing it with milk. The SlimFast meal replacement shakes contain four grams of fiber and is a popular meal replacement product that helps you control your hunger.

Always note the ingredients when you consider taking meal replacement shakes for weight loss. What stands out is the numerous vitamins and minerals that you get in the SlimFast shake mixes. Unfortunately, the product contains ingredients such as 10 grams of sugar that may increase inflammation and blood sugars and artificial sweeteners such as acesulfame potassium that may adversely affect the gut microbiome[5] and, ultimately, blood sugar.

The vitamins in the product include the following nutrients: vitamin A at 150 micrograms (mcg), vitamins B1/thiamin (0.3 milligrams (mg), B2/riboflavin (0.18 mg), B3/niacin (5 mg), B6 (0.5 mg), B7/biotin 10 mcg), B12 (1 mcg), C (27 mg ), D (2.5 mcg ), E (13.5 mg), and K (20 mcg).

SlimFast shake reviews show the product includes calcium (190 mg ), iron (6.3 mg), potassium (260 mg), folate (100 mcg), phosphorus (80 mg), iodine (15 mcg), magnesium (90 mg), zinc (3.3 mg), selenium (16 mcg), copper (0.18 mg), manganese (0.7 mg), chromium (10 mcg), and molybdenum (15 mcg).

The ready-to-drink meal replacement shakes are tasty and only require mixing with milk or other suitable beverages. Add 1 level scoop of the SlimFast Meal Replacement Shake into a blender and mix with milk and ice.

Intermittent Fasting Complete Meal Bars

SlimFast Intermittent Fasting Complete Meal Bars

The SlimFast Intermittent Fasting Complete Meal Bars are suitable for weight loss. These bars are rich in natural ingredients, including flavored milk coating made using maltitol, calcium caseinate, milk protein concentrate, cocoa.

  • Naturally flavored meal replacement bars
  • Contains 15 grams of protein and 10 grams of fiber
  • Has 24 different minerals and vitamins
  • Made at a facility that also processes milk, tree nuts, and soy products
  • Contains sucralose and malitol
  • Contains a bioengineered food ingredient

SlimFast meal replacement bars are perfect for folks who want to adopt an intermittent fasting lifestyle. The product can become part of your healthy diet as you lose weight. While eating the bars may not help you lose weight quickly, the 190 calories per serving are perfect for your weight-loss program.

These are small bars that you can carry anywhere you go. They taste great and provide advanced nutrition to your body. There are 15 grams of protein and 10 grams of dietary fiber per bar. It has only one gram of sugar for each meal replacement bar. 

However, it does contain sucralose, a sugar substitute found recently to significantly and adversely affect[5] the gut microbiome and, thus, blood sugar regulation. Also contained in the formula is maltitol, a sugar alcohol[6], which has been linked to a worsening of irritable bowel syndrome and may aggravate digestive problems such as diarrhea and gas.

Keto Fat Bomb Snack Cup

SlimFast Keto Fat Bomb Snack Cups

The SlimFast Keto Fat Bomb Snack Cup meets your snacking needs when planning for meals and snacks. It contains real ingredients beneficial to the body, such as milk chocolate coating, cocoa butter, chocolate erythritol, whole milk powder, non-fat dry milk, inulin.

  • Low-carb meal replacement product
  • No added cane sugar but does contain stevia and erythritol
  • Gluten-free SlimFast snack cups
  • Made in a facility that processes wheat, tree nuts, and eggs

SlimFast reviews show that Keto Fat Bomb Snack Cups are among the most popular meal replacement products. These are perfect to have in between main meals to help curb cravings. This is ideal to have on a Keto diet, as per SlimFast Keto reviews

The meal replacement snacks come in a convenient small pack and are healthy to enjoy. These are low-calorie products for snacking and providing the body with advanced nutrition. Snack cups are shelf-stable and portable when you pack a meal. They’re also good to store in the pantry.

 And, of all the sweeteners that could be used, stevia and erythritol are the safest. Stevia has only a modest effect on the gut microbiome, while erythritol might even have some health benefits.

On top of the real and nutritious ingredients are minerals such as calcium (26 mg ), iron (1 mg ), and potassium (62 mg ). As per the 1-2-3 plan, you can have three Keto snacks daily when following the SlimFast diet plan. The calcium content promotes good bone health[7].

Advanced Nutrition Shakes

SlimFast Advanced Nutrition Shakes

The SlimFast Advanced Nutrition Shakes fit the bill regarding ideal meal replacement shakes. This product contains such ingredients as water, milk protein concentrate, 24 vitamins and minerals, canola oil, cocoa, maltodextrin, cellulose gel, potassium phosphate, mono and diglycerides.

  • Contain 20 grams of drinkable protein
  • Has only one gram of sugar per serving
  • Contains 24 essential vitamins and minerals
  • Can be a little too sweet
  • Does contain artificial flavors and colors
  • Contains sucralose and maltodextrin

Enjoy the Advanced Nutrition Shakes that have a higher protein content. Protein is good when you want to maintain a healthy weight, build muscle and have a speedy recovery after a workout. On top of that, the shake contains five grams of dietary fiber and only nine grams of total fat, along with its 24 vitamins and minerals.

Each serving of the meal replacement shake contains 180 calories. There are artificial flavorings and colors worth noting. As per the 1-2-3 SlimFast diet plan, you can take 2 SlimFast shakes daily.

Controversial ingredients are included in the formulary, such as sucralose[5] and maltodextrin[8]. Both chemicals, while approved by the Food and Drug Administration (FDA), alter the gut microbiome adversely, thus potentially negatively impacting blood sugar control and immunities. Controversial ingredients are those entities suspected of causing harm but have not accumulated sufficient evidence from human scientific trials to warrant being taken off of the FDA’s list of safe ingredients and may actually be banned in other countries.

Alternatives To SlimFast

ProductLYFE fuel Daily Essentials ShakeOrgain Organic Protein ShakeVega Organic All-in-One Shake
NameLYFE FuelOrgainVega
ProsPlant-based whole food meals
Gluten-free and soy-free
Made using ethically sourced ingredients
Comes in delicious flavors
Contains organic shake perfect for kids
Non-GMO and gluten-free
No artificial flavors and preservatives
Comes in different flavors
Contains high protein content
Good for high nutrient content
Plant-based products
ConsTaste can be overly sweetTaste can be overwhelming for someCan be high-priced
Full reviewLYFE Review Orgain Review Vega Review

Final Thought

The SlimFast diet plan is a good way to lose weight and attain your weight loss goals. According to SlimFast reviews, the products can help you lose short-term weight. And it’s a plus that all products have high levels of minerals and vitamins. However, many products contain a significant amount of sugar, artificial flavors, sweeteners, and ultra-processed chemicals such as maltodextrin that are not beneficial to your overall health and should be considered when making a product decision.

Most meal replacements work when there’s a calorie deficit which you can achieve with SlimFast. This is possible by following the 1-2-3 meal plan. This includes one sensible meal, two meal replacement shakes, and three daily snacks. It is worth noting that some of the products are low in protein compared to other meal replacement shakes, such as the SlimFast Original meal replacement shake, which has only two grams of protein per scoop of powder.

However, it’s good to pair the SlimFast diet with behavioral changes to achieve long-term weight loss. Eating a healthy diet, using low-fat food preparation techniques, and avoiding processed foods after the plan ends help keep the weight off. Consult a registered dietitian before committing to meal replacement.

Frequently Asked Questions

Who is SlimFast good for?

SlimFast meal replacements are good for people who want to achieve short-term weight loss interventions. It helps you maintain a calorie deficit while working to burn fat but may not provide enough protein for effective muscle building.

Will SlimFast products help me lose weight?

Yes, SlimFast meal replacements can help you lose weight. However, this can work best for a short duration. After that, it’s good to make changes that work towards healthy eating and maintaining an active lifestyle. SlimFast Diet reviews suggest that the shakes are designed for those who want to lose weight fast with little fuss.

Does SlimFast work?

Yes, it does work because you end up eating fewer calories than you need. Limiting your meals to one a day and adding two meal replacement shakes and three snacks mean you cut off about 800 calories from your diet on average. Other SlimFast shakes reviews suggest that the diet lacks variety, and many healthy foods are cut out, thus making it unsustainable.

Does SlimFast have any side effects?

As you work towards weight loss, you have to eat fewer calories to enjoy the benefits of a calorie deficit. Eating less can result in symptoms[9] like lightheadedness, nausea, and at times feeling cold.

+ 9 sources

MIDSS adheres to strict procurement guidelines and relies on peer-reviewed studies, academic research institutes, and medical associations. We work mainly with peer-reviewed studies to ensure the accuracy of the information. We avoid the use of tertiary references. You can read about how we ensure the accuracy and timeliness of our content in our editorial process.

  1. USDA (2020). Dietary Guidelines for Americans 2020 -2025 Make Every Bite Count With the Dietary Guidelines. [online] Available at:
  2. Truby, H., Baic, S., deLooy, A., Fox, K.R., Livingstone, M.B.E., Logan, C.M., Macdonald, I.A., Morgan, L.M., Taylor, M.A. and Millward, D.J. (2006). Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC ‘diet trials’. BMJ, [online] 332(7553), pp.1309–1314. doi:10.1136/bmj.38833.411204.80.
  3. Gudzune, K.A., Doshi, R.S., Mehta, A.K., Chaudhry, Z.W., Jacobs, D.K., Vakil, R.M., Lee, C.J., Bleich, S.N. and Clark, J.M. (2015). Efficacy of Commercial Weight-Loss Programs. Annals of Internal Medicine, [online] 162(7), pp.501–512. doi:10.7326/m14-2238.
  4. Astbury, N.M., Piernas, C., Hartmann-Boyce, J., Lapworth, S., Aveyard, P. and Jebb, S.A. (2019). A systematic review and meta-analysis of the effectiveness of meal replacements for weight loss. Obesity Reviews, [online] 20(4), pp.569–587. doi:10.1111/obr.12816.
  5. ‌Suez, J., Cohen, Y., Valdés-Mas, R., Mor, U., Dori-Bachash, M., Federici, S., Zmora, N., Leshem, A., Heinemann, M., Linevsky, R., Zur, M., Ben-Zeev Brik, R., Bukimer, A., Eliyahu-Miller, S., Metz, A., Fischbein, R., Sharov, O., Malitsky, S., Itkin, M. and Stettner, N. (2022). Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance. Cell, [online] 185(18), pp.3307-3328.e19. doi:10.1016/j.cell.2022.07.016.
  6. Staff, U. (2020). Maltitol: What You Should Know About This Common Sweetener. [online] University Health News. Available at:
  7. Vannucci, L., Fossi, C., Quattrini, S., Guasti, L., Pampaloni, B., Gronchi, G., Giusti, F., Romagnoli, C., Cianferotti, L., Marcucci, G. and Brandi, M.L. (2018). Calcium Intake in Bone Health: A Focus on Calcium-Rich Mineral Waters. Nutrients, [online] 10(12), p.1930. doi:10.3390/nu10121930.
  8. Gerasimidis, K., Bryden, K., Chen, X., Papachristou, E., Verney, A., Roig, M., Hansen, R., Nichols, B., Papadopoulou, R. and Parrett, A. (2019). The impact of food additives, artificial sweeteners and domestic hygiene products on the human gut microbiome and its fibre fermentation capacity. European Journal of Nutrition, [online] 59(7), pp.3213–3230. doi:10.1007/s00394-019-02161-8.
  9. Pi-Sunyer, F.X. (1993). Short-Term Medical Benefits and Adverse Effects of Weight Loss. Annals of Internal Medicine, [online] 119(7_Part_2), p.722. doi:10.7326/0003-4819-119-7_part_2-199310011-00019.


Mitchelle Morgan is a health and wellness writer with over 10 years of experience. She holds a Master's in Communication. Her mission is to provide readers with information that helps them live a better lifestyle. All her work is backed by scientific evidence to ensure readers get valuable and actionable content.


Kathy Shattler, MS, RDN
Medical Reviewer
Kathy Shattler has been a Registered Dietitian for over 25 years and currently runs her own Telehealth Clinic while freelance writing in her spare time. She graduated with a Master of Science degree in Human Nutrition from Michigan State University and has a plethora of experience in both clinical nutrition as well as public health. She has been deemed a trailblazer in her profession and continues to strive for excellence in public health education in integrative medicine and in her professional writing career.

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