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SlimFast Keto Review - 13 Things You Need to Know

Slimfast Keto: another well-known company on the keto train? For over forty years, SlimFast has produced weight loss products like nutritional bars and meal replacement shakes.

SlimFast Keto provides a plan to support dieters who wish to try a ketogenic diet. Along with a sensible diet and regular exercise, the program claims that dieters can see results in one week.

Our research team wanted to look into the SlimFast Keto products to determine their overall effectiveness as part of the ketogenic diet, including ingredients and clinical research. The research team found lots of information, including some things you’d never guess about the keto diet.

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What is SlimFast Keto?

The SlimFast Keto line provides products for consumers on a high-fat, low-sugar, low-carbohydrate ketogenic diet. The keto diet is designed to keep users in a fat-burning state called ketosis.

SlimFast Keto products include keto smoothies and bars and keto-compatible supplements. SlimFast claims that following their low-carbohydrate diet plan will provide some of the following benefits:

  • Rapid fat burning
  • Hunger suppression
  • Ability to eat foods like bacon and steak

SlimFast Keto Competitors

Kara Keto Burn
Kiss My Keto
Pruvit Keto OS

How Did SlimFast Keto Start?

SlimFast has been in business since 1977; focusing on SlimFast diet pills, shakes, snacks, prepackaged meals, and other products for managed weight loss. SlimFast also provides meal plans to help consumers attain their health goals.

Beginning in 2004 in response to demand for low-carb products, SlimFast first produced the lower-sugar SlimFast Optima line and recently introduced SlimFast Keto products for the needs of a ketogenic diet.


SlimFast Keto Claims

SlimFast Keto products claim to help keep dieters in ketosis. While the official site acknowledges that there is no “magical, quick-fix cure for weight loss,” a low-carbohydrate keto diet such as the SlimFast diet plan can play a significant role in weight loss.

According to a study by the Experimental and Clinical Cardiology, on a ketogenic diet, the weight and body mass of obese patients “decreased significantly.”

The SlimFast Keto Diet also claims a ketogenic diet will help reduce hunger pangs by suppressing hunger hormones while also allowing dieters to eat satisfying foods like steak.


SlimFast Keto Ingredients

SlimFast Keto products include meal replacement shakes, snacks, and dietary supplements. All of the products provide low-carbohydrate, high-fat nutrition.

Some key SlimFast Keto ingredients include:

  • MCT Oil Blend (palm, coconut, grass-fed butter)
  • Protein Blend (whey protein concentrate, whey protein isolate)
  • Grass-Fed Collagen Peptides
  • Cocoa
  • Erythritol


MCT Oil is an oil made of medium-chain triglycerides (MCT) that commonly occurs in coconut oil. Medical News Today acknowledges that MCT oils such as coconut oil help reduce obesity in mice. MCT oils help raise the fat content of SlimFast Keto products and help promote a feeling of fullness.


Erythritol is a sugar alcohol. Erythritol is a modified form of sugar that does not raise your blood sugar level, according to the European Journal of Clinical Nutrition


SlimFast Keto products frequently feature a natural sweetener called Stevia. Although stevia is 300 times sweeter than standard sugar, it has a limited caloric impact and has been used in foods in Japan since the 1970s.

Whey Protein and Collagen Protein

As shown in Obesity Research and , MCT oils allow the body to generate more energy, which gives dieters more room to eat satisfying proteins. Whey and collagen protein enable cells to rebuild themselves, which is especially important in conjunction with a healthy exercise program, as the SlimFast diet plan recommends.

Does SlimFast Keto Work?

Any diet or exercise plan has variable results depending on a person’s health and general commitment to the plan. However, as the International Journal of Environmental Research and Public Health points out, the ketogenic diet does tend to be effective for some different possible reasons:

  • Control of appetite hormones
  • Appetite suppressant effect of ketones

The SlimFast Keto diet, designed to maintain ketosis, has the potential to help dieters achieve these results.

Benefits & Results

SlimFast Keto Benefits and Results

SlimFast Keto results will vary. The products are designed to get dieters in a state of ketosis. In ketosis, the body uses fat to produce ketones, which are small molecules used for energy.

In short, an important benefit of the SlimFast Keto diet plan is that your body will burn its own stored fat to power you. The results of a long-term ketogenic diet have not been studied extensively.

Details on SlimFast Keto and Weight Loss

An important aspect to understand about this keto diet plan is that dieters replace two daily meals with SlimFast products including shakes, bars, or cookies to reduce hunger and maintain metabolic rate at a higher level.

For optimal weight loss, the SlimFast diet strongly advises dieters to avoid sweetened beverages and sweets in general. SlimFast Keto results depend on keeping sugar and carbs to a minimum.

Weight loss is more likely to occur when dieters keep themselves in a ketogenic state. Sugars or excessive carbohydrates will make the body “switch over” from burning fat to burning the carbs in food. This will cause weight loss to slow down, or more likely, reverse, so you gain weight.


How to Use SlimFast Keto

SlimFast Keto products can be used individually on an as-needed basis by dieters wanting an occasional low-carbohydrate snack or meal replacement shake. Additionally, SlimFast products can form an important part of an overall health program.

One to two meals a day can be replaced by SlimFast shakes, bars, or snacks. The final meal of the day can follow recipes or suggestions on the SlimFast keto diet program. Ideally, the meal should be higher in healthy fats, adequate in protein, and low in carbohydrates.


How Much Does Slimfast Keto Cost?

The official SlimFast website does not list prices for its items. Is SlimFast Keto on Amazon? Yes, and the products are easy to find. Some representative costs of specific SlimFast Keto products are as follows:

  • Keto Meal Replacement Peanut Butter Fat Bomb: $9.93 per box
  • Keto Meal Replacement Bar: $9.97 per box
  • Keto Meal Replacement Powder Fudge Brownie Batter: $14.23 per canister
  • Keto Creamer: $10.79
  • MCT Oil: $15.97
  • Ketone Test Strips: $9.97
Side Effects

Potential SlimFast Keto Side Effects

Potential SlimFast keto side effects can vary. Medical News Today points out that especially if dieters are new to ketosis, they may experience sluggishness, constipation, or low blood sugar.

Other keto dieters experience what is known as “keto flu,” a general feeling of lowered energy as your body adjusts from burning carbs to burning fat. Keto flu can be helped by drinking water with electrolytes.

Pros & Cons

SlimFast Keto Pros and Cons

SlimFast Keto products, if used as part of an overall health management program and regular exercise, may help dieters lose weight. Weight loss in a low-carbohydrate plan usually happens quickly before some degree of plateauing or tapering.

One downside to the SlimFast program may be the limited number of products available through the SlimFast Keto line. As Harvard University states, a low-carbohydrate diet can be challenging to stick to over the long run. Lack of food variety may cause dieters to lose interest.

What Users Are Saying

“I can stomach a lot of the meal replacement bars out there but this one is just awful. The size and look of the bar is appealing but the actual taste is disgusting and leaves a horrible taste in your mouth. The texture is even weird. Not sure those are actual chocolate chips or what? This is such a miss compared to the shake – which I love.”

“Great tasting shake that is making the keto transition much easier. Blends nicely and isn’t chalky or gritty like other shakes I have tried.”

“Taste is tolerable… has the typical stevia aftertaste. Since it contains MCT oil, I do not recommend this unless you have ready access to a toilet for a few hours after consumption. On the other hand, maybe it’s a good remedy for “keto constipation”.”

Bottom Line

Bottom Line on SlimFast Keto

The SlimFast Keto line claims that dieters can lose weight with a minimal amount of hunger pangs or cravings by using SlimFast Keto products as part of an overall weight management plan in combination with exercise.

We’re all for moving toward a healthier life, but sometimes, it can be hard to make those lifestyle changes needed. Luckily, clinically-proven programs exist to make the transition a whole lot easier.

One the best weight-loss apps we’ve seen is one called Noom. Noom provides users with everything they need to start making healthier choices and lose some weight along the way, plus an amazing app so you can access your personalized plan from anywhere.

Dietspotlight readers can now try Noom as part of a 14-day trial for a limited time – something you might want to take advantage of!

Learn More About Noom »
SlimFast Keto Review
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SlimFast Keto

Is Slimfast Keto for weight loss?

Slimfast Keto products support a low carbohydrate, high fat diet for weight loss.

What are the Slimfast Keto ingredients?

MCT Oil Blend, protein blends, cocoa, Erythritol, grass-fed collagen peptides

Are there Slimfast Keto side effects to know about?

Side effects of Slimfast Keto are possible tiredness, constipation, and a lowered sugar level.

Is Slimfast Keto safe?

This product is generally considered safe for men and non-pregnant women over 18.

Where can I buy Slimfast Keto?

Slimfast Keto is available with online shopping, such as Amazon, or most health and supplement stores.

Is there a Slimfast Keto free trial or free samples?

Currently free trials or samples are unavailable.

What is the most common Slimfast Keto complaint?

There are a limited amount of products available.

What are some similar products to Slimfast Keto?
TruKETO, and Kara Keto Burn are similar products to Slimfast Keto.
Are Slimfast Fat Bombs Keto?

The Slimfast Fat Bombs are keto-friendly.

How many carbs are in SlimFast Keto?

The amount of carbs in Slimfast Keto products will depend on what you choose to consume and in what flavor.. For example, the Slimfast Keto Meal Replacement Mix in Cake Batter contains 5 grams of net carbs.

Is SlimFast Keto actually keto?

Slimfast Keto says it is a good choice for ketogenic diet followers as their products are low-carb and easy to use.

29 SlimFast Keto Reviews

    Helen (Verified Purchase)

    I just tried the Fudge Brownie Batter shake this morning. It is AWFUL! It left such a HORRIBLE aftertaste that I couldn’t even finish the whole shake! Not even going to try the fat bombs. Everything is going back to Walmart and, hopefully, I can get a refund.

  • These made me so sick
    K (Verified Purchase)

    I have an iron stomach. I can eat almost anything. Having said that, these shakes have made me so sick I can’t even explain it. Two days in a row after drinking the shake, immediate flushing and hot feeling, stomach cramps and burning. I feel like I’m going to lose it out of one end or the other. This is a horrible feeling. Never experienced anything like it. Avoid. Avoid. Avoid.

    • CJ

      Same thing for me, I don’t know what it is because I was previously drinking “bulletproof coffee” (mct oil + natural butter) every morning without the same feeling. I think it’s the whey for me, I don’t know. The bars and fat bomb snacks are fine but the shakes give me the same result. I’ll be trashing them and going back to my coffee in the morning.

    • Nic

      Same thing happened to me! The first day I just thought I was sick. The second day I got the same feeling immediately following the shake. I got a burning sensation in my stomach and felt completely nauseous.

      • Melanie

        Same!!! I have tried it on multiple occasions and it makes me sick as hell Everytime!

        • Anonymous

          Same here. Got the runs within an hour

    • David Palmer

      Yes me to it is the mct oil to much for me my wife has no problem with it!

  • Sick 🤢
    Robin (Verified Purchase)

    No wonder it says it curbs appetite for 4 hours… I’ve been nauseous and sick to my stomach ever since I drank the shake! Will not be trying it again!

    • Patricia

      Me too!! I couldn’t figure out why it was making me so sick!! I’ve been on a Keto diet for months and nothing has ever made me feel this bad!!! I’m done it!!!

  • Sick 🤢
    Anonymous (Verified Purchase)

    No wonder it says it curbs appetite for 4 hours… I’ve been nauseous and sick to my stomach ever since I drank the shake! Will not be trying it again!

  • Instant stomach pain and cramping!
    Shelly McDonald (Verified Purchase)

    I had instant pain and cramping when it hit my stomach. Day one I chalked it up as a fluke… when it occurred the second day, I did not finish the bottle and will not be drinking the other two… What a waste of money.

    • tammy

      me too!!!!! exactly the same!!!! my tummy hurt every time!!! horrible! for a long time after why!

    • Stephanie White

      I also get stomach pains immediately. I love the shake taste and it makes me sad. I wish this product didnt do this to me. I’ve tried 3 different times with the same effect each time. 🙁

      • Anonymous

        Luis – we get it. Thanks for cut and pasting the same exact thing in every reply.

    Lakeisha Burse


  • I drank the Keto Slim Fast and immediately my stomach started to burn, cramp and just sick. I was in the bathroom all day with diarrhea! I was sick! I thought maybe my body had to get adjusted to it so I took it like crazy person again the next day. The same thing happened except it was worse! I normally drink the Advanced Slim Fast so I stopped drinking the Keto Silm Fast and went back to the Adavanced Slim Fast and I have NO PROBLEMS!!! I DO NOT RECOMMEND SLIM FAST KETO!!!
    LAKEISHA BURSE (Verified Purchase)

    Burning, Cramping, and Simply Sick!!!

    • tammy

      same but not the last because i hv constipation im sure but i drink the others never a problem either!

  • Cramping and Pain
    Katherine Lostritto (Verified Purchase)

    I drank the keto shake about an hour ago and have cramping and used the restroom. I’ve been keto for about a year and a half, use one tablespoon MCT oil daily in my coffee, and am used to the keto diet. No clue why I feel so bad…

    • Lakeisha Burse

      I am so glad to read that others experienced this problem too. Something is not right. I drank the Vanilla Cream and it tasted great but it went horribly wrong in my stomach!

    • Lauren

      I have just started using the slimfast keto products and I haven’t had any problems until today. I tried one of the shakes and ended up with stomach issues and threw up. I think (but can’t find a true ingredient list) they’ve put cayenne pepper in the shakes. This is my thoughts because I’m not able to eat spicy foods without having to throw up due to acid reflux (I think). When I got sick from the shake, not to be gross, but it was like there was a lot of cayenne pepper there and left my mouth burning like I’d had spicy food. Just a thought, but maybe they’ve put too much cayenne pepper into the shakes?

  • Sandra

    Why do the shakes hurt my stomach immediately after drinking?

    • Anonymous

      Mine too…I had to rush to the bathroom and I’ve been on keto for a while now. What a scam..10.00 to make you sick !

  • Never again
    Dana (Verified Purchase)

    I tried keto shakes after a few sips my stomach was burning. Will not use again.

    • Christi

      I had the burning too. was wondering if it’s because I’ve had diverticulitis in the past.

  • Instant side effect. Not worth it for me.
    Anonymous (Verified Purchase)

    I tried a bomb today and 2 hours later was in the bathroom for the rest of the evening intestinally sick!
    Never again!

    • Abigail

      It took just 30 minutes for me and I threw up after taking the Slimfast Keto Shake this morning. Of course I didn’t see this long thread of complaints until after the fact. Will be returning the rest of the package back to the store. Not worth the trouble for me.

  • Nutritive Sweetener?

    Nutritive Sweetener? Is that safe for Keto? No artificial sweeteners should be used while on a Keto diet lifestyle. Is this referring to Stevia?
    Why does this cause constipation? MCT Oil and Collagen cause diarrhea.

    • some doktor

      no mct oil doesnt. fibre might do. but i just wanted to see how many poeple know that this is a scam product keto means 5% carbs or less this will just make you fat. it has a 2:3 carb fat ratio. thats the perfect way to get obese. and the package is misleading

      • Lauren

        I’ve tried losing weight with everything else but never could. I’ve finally lost 10 pounds in my first 3 weeks of using these keto products.