Updated: 02/02/2016 - Sponsored by Leptigen

SlimFast Review - Does This Meal Replacement System Work? Are bad taste and dietary side effects deal breakers?

Editor's Review: 3.2 / 5.0

slimfast-product-imageConvenience and efficacy are the two biggest factors in modern weight loss programs, and we’ve heard consumers discussing the pros and cons of Slim Fast for a while now. We decided to review the product carefully to get a feel for the ingredients, customer service, clinical studies, and side effects. Then we explored as many customer reviews online as we could find, and we condensed all of that information here into a brief summary.

EDITOR'S TIP: Combine SlimFast with a proven fat burner such as Leptigen for better results.

What You Need To Know

Here’ a brief summary of the product: Slim Fast meal replacement shakes contain fat free milk, water, sugar, cocoa (processed with alkali), gum Arabic, calcium caseinate, cellulose gel, canola oil, potassium phosphate, cellulose gum, soybean lecithin, mono and diglycerides, artificial flavor, carrageenan, maltodextrin, and dextrose. Users are instructed to replace breakfast and lunch with these 11 oz. shakes and to supplement with a few small snacks. The shakes seem fairly practical, so the user can consume them at home, in the car, or at the office.

Slim Fast has been around the block once or twice–it was initially introduced in 1977. Fueled by Tony Lasorda’s spokesmanship, the product grew, and today it is owned by Unilever. You can purchase Slim Fast from online retailers or from stores like Walgreens and Walmart, although you can’t purchase the shakes directly from Slim Fast online. There are some studies suggesting that Slim Fast works, and the emphasis on keeping calories down is a plus, but read on…

Side Effects–Can Users Handle the Taste for Very Long?

We read through many online reviews, and the question of taste kept coming up. “Simply put, you will lose weight if you burn more calories than you eat,” said our research editor. “Slim Fast provides you with a way to quickly replace breakfast and lunch with a shake rich in protein, and if you stick to it, you should shed some pounds. The problem is, you have the same shake to look forward to two times every day.” That’s replacing two meals with shakes twice a day for 8-10 weeks.

“I purchased Cappuccino Delight. Delightful it’s NOT. It tastes gross and reminds me of burnt coffee beans,” said one customer. He wasn’t the only one.

“Too much sugar, way too sweet and chocolaty. Does not feel like a meal after either,” said another user about a different flavored shake.

Scroll below for one of the best products we’ve seen over the last year.

Another Concern–Digestive Side Effects

As we read through more and more reviews, another trend began to emerge–undesirable digestive discomfort. “It gave me very bad gas and diarrhea. Never tried it again,” said an unhappy customer.

“The first gave me stomach pain followed by diarrhea. I had a bottle this morning and within an hour the diarrhea began again,” said another. Other customers seemed to think that the high concentration of sugar (not found in every flavor) had a negative impact on the way they felt. “18 grams of sugar–it is so sweet. It stays in your system for days,” said another reviewer.

It’s no secret that side effects can hamper the ability of a supplement to produce long-term results, but our research has shown that even a minor annoyance with a product can really disrupt a customer’s loyalty to it. If Slimfast does have a bad taste, and if it does lead to undesirable (albeit minor) digestive discomfort, a user is unlikely to stick with it for the necessary 8-10 weeks.

That brings us to the science–Is it proven to work?

Slimfast, believe it or not, is one of the few diet products that has been clinically verified to have an effect on weight loss. Given the longevity of the product, the fact that it has been featured in clinical studies is no surprise, and you can be sure that a lengthy and regular engagement with Slim Fast will lead to a few pounds lost. Unfortunately, digestive discomforts and the prospect of drinking two Slim Fast shakes per day may not be worth the moderate weight loss.

The Bottom Line: Should you try Slim Fast?

While the decision of whether or not to try Slim Fast is ultimately up to you, the information found in this review has hopefully been a help. We like the longevity of Slim Fast, and the fact that it is featured in clinical studies is reassuring. The poor reviews regarding the taste and the fact that it just doesn’t “sit well” with everyone are certainly cause for concern, however, and there are plenty of other meal replacement programs out there to try.

If you still need to trim down a bit, we suggest looking for a product that won’t replace actual meals with a bad-tasting substitute and won’t lead to digestive irregularities.

We’ve been repeatedly impressed with a supplement called Leptigen this year. It features a proprietary blend of four ingredients–all of which have been clinically studied–that burn fat and boost metabolism. We’ve looked for talk of negative side effects, and we can’t find any; the online reviews are overwhelmingly positive.

Better yet, the makers of Leptigen are offering a special trying offer for the time being. It’s always a good sign when the makers of a product are willing to stand behind it.

Learn More About Leptigen »
GD Star Rating

How Does SlimFast Compare?

Previous SlimFast Review (Updated November 5, 2014):

What You Should Know

Click Here To See Our Highest Rated Review

Slim-Fast is a well established company that has been around for many years. It produces a wide variety of products that range anywhere from shakes to candy bars. Claims have been made that these products can help you to lose weight by reducing your calorie intake, but providing you with the proper nutrition and vitamins that your body needs. It is said that Slim Fast is easy to follow and it won't make you hungry. We will now take a closer look so it may be determined if these claims hold any relevance.


The contents of Slim Fast Ingredients, in most of their products, are Fat free milk, water, sugar, cocoa (processed with alkali), gum Arabic, calcium caseinate, cellulose gel, canola oil, potassium phosphate, cellulose gum, soybean lecithin, mono and dyglicerides, artificial flavor, carrageenan, maltodextrin and dextrose.

Product Features

Slim Fast does not appear to contain any special ingredients that really stick out as a "weight loss supplement". Basically, it is believed that the main purpose of the product is to make sure that your body is receiving the proper amount of nutrition by really making an attempt to include all of the daily dietary needs by combining the product with what Slim Fast likes to call "sensible meals". According to a source, you may be able to achieve these results by either using their products as a meal replacement, or by combining them with other foods that you may already have in your pantry or refrigerator. They recommend that you eat 2 meals a day that includes one of their products for each one, and one sensible meal at night with snacking in between. Of course, the snacks would also be Slim Fast products. It appears that Slim Fast's main goal may be to encourage you to eat less of regular everyday foods and replace them with Slim fast products. This will result in less food and less calories, but it may be delivering the proper amount of nutrition to your body while doing so.

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  • One advantage of this is that it appears that you still get to eat regular foods with the available meal plan system.
  • Slim Fast products can be found nearly anywhere from shopping centers to drug stores.
  • Slim Fast provides online support and helps to plan your menus


  • Most nutritionist may believe that this is not a long term solution to weight loss.
  • Nutritionist may also believe that the caloric intake is not enough.
  • It seems to contain too much sugar, probably resulting in an energy boost then a crash.
  • This does not appear to contain an effective metabolism booster.


Slim Fast appears as though it could be an effective weight loss regimen. However, there may be some concerns about the amount of sugar that is included in these products. These days manufacturers tend to put less sugar in products due to the crash and burn effects that it can have, especially when following a diet with such low caloric intake. Also, it may not be realistic to believe that this is a lifelong solution to weight loss due to the fact that someone simply may want to go their entire lives having to buy Slim Fast products in order to maintain their weight.

21 User Reviews About SlimFast

Leave comments below
  • 1

    It is about 5 days now I started taking slim fast shake.i have severe gastric problem. But I am not sure it is because of this product.i wanted to know if I consume for long term, is there any health issues with this product. Thanks


    Stephen (Editor)

    Hey, Reema! We’ve not heard complaints of long term use, according to SlimFasts’ studies. If you are experiencing discomfort we suggest stopping and asking your doctor if these problems persist.


  • 2
    Connie Belt

    My thoughts are, that i can never find French Vanilla on the shelves at Walmart in Paducah, Ky. I love this product and it is very frustrating not to be able to find it!! I even went on line to purchase it and they were sold out! But last week they had it, but was only going to let me buy 2, when I was wanting 10 cans. I like the powder so I can mix it myself. Thank you for listening. Connie Belt


  • 3

    slim fast contain to much sugar I start to take tons of water after using this product for one month .I will quit it inmmediately.


  • 4

    nursing infants….good or bad?


  • 5
    John Frohock

    I have been a long time user of slim-fast shakes. Today I am quitting. The reason is inconvenience of the new plastic bottles. I use to have my shake on the run. Pop the top and drink it on the drive to work. Now I have to remove the cap, remove the aluminum foil and figure out a place to put them while I drink my shake. The top of the bottle feels funny when drinking from it, and the bottle is to small; falls over in the cars’ cup holder. Looks like the price went up when you shifted to plastic as well. I’m dissapointed.


  • 6
    Judith Rubiel-Perez

    I went to the pharmacy to pick up meds and slimfast and was shocked at what I saw. Now your company is cheating us out of your product. I use to get a 12 pack now its an 8 pack. It use to be 11 ounces, now its 10 ounce. The 6 packs are now 4 packs for the same price. What the heck is going on? I feel your company is starting to screw the consumer. Does your company think that us consumers are stupid, do you think just because you put your product into a plastic bottles that we well be happy? Not me.. If your going to give us the same amount in your plastic bottles then fine and dandy, but don’t take away the volume. I think you need to talk to your marketing dept or your CEO and tell them that the public is not happy. The sales person said she had several complaints since your product hit the shelves. Its bad enough our gas and cost of living is going up, and now the one thing I felt I could afford to help me with my weight problem has gone up. I think you need to do some changes before people start to boycott your product…A concerned consumer.



    I agree with your comment. I will go to another brand. It is the price. slimfast take note, the price would usually be around $1.00 a can. the price per can has now gone up 40%. I don’t need that headache.


  • 7

    At 7 or 8 dollars for a 6 pack, it’s really expensive. I found some shakes at Aldi that taste just like them, same vitamins, less calories, and it’s 2.99 for a six pack on sale. Regular price is 4.29.



    What’s the name brand and do they offer a powder you can mix because I am lactose intolerent?



    whats the name of this cheaper drink?


  • 8

    I do love this program, it’s worked for me, and I continue exercise 3 times a week,also control myself do not eat after 6 pm. avoid from sweet. it’s good product.


  • 9

    How much sodiun is in a slim fast drink


  • 10

    Slimfast worked for me. i lost 3 lbs in the first week on the 3-2-1 plan & still losing about 2 lbs a week.



    Hey , you said you lost 3 lbs the first week. I was wondering how much exercising your doing with the diet to get those results, and what exercises are you doing? I wanted to try the SlimFast 3-2-1 Plan, but I wasn’t completely sure if it worked. Thanks.


  • 11

    what happened when your menstrual cycle won’t for a month with slimfast


  • 12
    Betty Hamilton

    When will Slim Fast be back in Southfield Mi Or Liviona MI


  • 13
    Kelly Southard

    Yes, I would throw them away. All Slim Fast shakes in a can from 2009 have been recalled. The powder and slim fast bars are ok. It’s just the cans.


  • 14
    Darlene Briggs

    i have 3 six-packs of Slim Fast Diet Drink that I purchased in 2009. My brother said That I should throw this away as it had been recalled. Is this correct? Please advise.


    Lawrence Smith

    Hello: I read your article on the ingredients in slimfast. For five years I have been using slimfast once a day in the morning. I usually mix a quart bottle in the night and it last about two days. During this five year period I had colitis of the stomach. Only recently did I hear that these problems can be caused by diet. I decided to eliminate foods form my diet to see what could be causing the colitis. I got down to milk and slimfast. When I stopped drinking milk with slimfast my symptoms finally went away. I thought at first it was the lactose, so I went for several days without any milk or slimfast, the symptoms are gone. They I started to see if I could drink milk with no lactose. For several days the symptoms have still been gone and I dont have to take the medicine which cost me $100 a month any longer. I believe the slimfast has been causing me colitis all these years. I am still off the medicine and slimfast and wont use the product any more. I would like to tell other people who may have colitis about this problem. Can you suggest places I can contact? Thanks very much Lawrence Smith


    Htay RN

    Lawrence, colitis of the stomach?? Colitis refers to the colon and has no referal to the stomach. Slimfast is not intended to be used “for five years” And a quart lasted you two days? That’s two servings you were drinking for one breakfast. With this is mind, I question your ability to mix the proper concentration. Don’t slam the product if you are not follwing direction of proper use.


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