Why are people talking about the SlimFast diet? Our attention turned toward ingredients, side effects, clinical research, peer-reviewed studies and customer service quality. Additionally, we dissected hundreds of dieter reviews and comments to see if anyone was successful in reducing caloric intake and weight. Then, we condensed and summarized to give you the information you need.
What is SlimFast?
First off, the Slim Fast diet is a meal-replacement system offering ready-to-drink shakes, 100-calorie snacks and nutrition bars. The ingredients include amorphophallus konjac , rhizome, apple pectin, oat fiber, fat free milk, water, sugar, gum arabic, canola oil, milk protein concentrate, cellulose gel, coffee powder, mono and diglycerides, potassium phosphate, hydrogenated soybean oil, natural and artificial flavors, maltodextrin, dl-alpha-tocopheryl acetate, phytonadione, thiamine mononitrate , riboflavin, niacinamide, pyridoxine hydrochloride, and folic acid. You’ll replace one meal and incorporate a snack as needed, ideally to curb appetite and keep blood glucose level between meals.
The Slim Fast diet was introduced in 1977. The official website and local grocery stores sell the product line. The longevity of the company and the affordability are positives, but read on…
Poor Taste – “Is it Flavorful?”
The first concern about SlimFast ingredients is taste. “Meal-replacement shakes , nutrition bars and snacks are intended to substitute regular foods,” said our Research Editor. “If the dieter doesn’t like the flavor, that is more than enough to keep them from sticking with the SlimFast products. If you don’t maintain a reduced-calorie diet, you are less likely to shed weight.”
“I purchased Cappuccino Delight. Delightful it’s NOT. The taste reminds me of burnt coffee beans,” said one customer using the Slimfast meal replacement.
“Too much sugar , way too sweet and chocolaty. Does not feel like a meal,” said another user.
On the other hand, we found SlimFast reviews that didn’t mention poor taste.
“Fills me up and tastes good,” reported a dieter.
Side Effects of Slim Fast – “Digestive Issues?”
As we read through more and more reviews, side effects of Slim Fast were a concern. “It gave me gas and diarrhea.  Never tried it again,” said a customer.
“The first gave me stomach pain. Within an hour the diarrhea  began again,” said another.
While SlimFast side effects were a concern for some, others didn’t mention adverse reactions.
“No gastrointestinal issues to speak of,” reported a customer.
“There’s no effects on my digestive system ,” stated another.
Our research has shown that it often takes a tiny thing, like Slim Fast reviews talking about side effects, to slash the dieter’s chances of success. If Slim Fast powder reviews do say it can cause some stomach or digestive issues, that could be an issue.
The Science – “Any Research Behind the Shake?”
Slim Fast does mention some studies relating to its effect on weight-loss. There’s even scientific evidence supporting using meal replacements to cut calories. Unfortunately, when we searched PubMed and various medical journals, we were unable to find any peer-reviewed studies to prove it works. It does contain protein and human studies have shown it to “[induce] sustained reductions in appetite.”  We’d like to see a little more soluble fiber, as that ingredient can slow the digestive process. 
At DietSpotlight, we look for solid science. When there’s no clear link to clinical studies, we get concerned. We’ve found far too many readers asking, does SlimFast work? We’d really need research to say yes, as it pertains to this specific brand.
The Bottom Line – Does Slim Fast Really Work?
So, are you heading out to buy a case of SlimFast meal replacement? Well, we like the longevity of the company and it’s affordable, but we’re hesitant about this one because the research doesn’t directly link it to weight-loss, there are no dedicated peer-reviewed studies and elements in the formula that could disrupt or slow the digestive process, like fiber, to reduce hunger and slow the onset of appetite are missing. We’re also concerned about the fact that beverages are not as effective as solid foods in terms of satiety. 
Do you want to trim down a bit? If so, we suggest going with a supplement with a formula containing clinically tested ingredients shown to help promote weight-loss. It’s not that we’re putting down SlimFast products, we just tend to err on the side of our scientific research.
Among the best products we’ve seen this year is one called Leptigen. It features four clinically-tested ingredients which have been shown to help accelerate metabolism, ignite fat loss and fight hunger. We’ve found some pretty amazing user reviews and customer service rocks.
Also, the makers of Leptigen are so confident in their supplement, they’re offering a Special Trial Offer.
Previous SlimFast Review (Updated November 5, 2014):
What You Should Know About Slim Fast Results
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. You can find 100-Calorie Snacks, Meal Replacement Shakes and Smoothies and Eat Less Pills on their website. 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. Easy to follow, Medifast is an alternate weight-loss program that offers specific foods to be consumed on a regular basis that include soups, entrees, bars, shakes in a four day meal plan.
Slim Fast Ingredients
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. You can also check out our Meal Replacement Article which talks about companies such as Slim Fast that extensively talk about meal replacements for weight loss.
Slim Fast 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". Similar to these sensible meals, Shakeology is a line of meal-replacement shakes high in protein discovered to reduce cravings. Although these proteins shakes are found to support a high supply of protein, the side effects still cause a concern for negative reactions. According to a source, you may be able to achieve these results by either using Slim Fast's 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 two meals a day that includes one of their products for each one, and one sensible meal at night with snacking in between. As it pertains to appetite suppressants, a good source for weight loss can be found in caffeine, one in particular product that resembles same results is Hydroxycut. Needless to say, this thermogenic can be taken once or twice a day, like Slim Fast. Caffeine is found to coincide with with healthy weight loss by suppressing the appetite and increasing energy levels. Of course, their 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 stimulant will result in less food and less calories, but it may be delivering the proper amount of nutrition to your body while doing so. You can find identical results in PhenQ affirming the supplement elevates energy levels with it's secret ingredient, caffeine.
Advantages of Slim Fast
- 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
Disadvantages of Slim Fast
- 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 results? It 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 diet products in order to maintain their weight.
SlimFast Questions & Answers:
We read hundreds of customer reviews about SlimFast meal replacement and other SlimFast products and put the most common questions into this helpful FAQ.
What are the side effects of SlimFast?
According to some customer reviews, SlimFast side effects may include digestive discomfort , diarrhea, and stomach pain.
Can Slimfast give you diarrhea?
We didn’t find any specific ingredients in Slimfast products that are associated with diarrhea, but some users have reported this side effect.
What is SlimFast made of?
SlimFast ingredients include 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.
Does Slim Fast work – how effective are the ingredients in Slim Fast?
SlimFast meal replacement shakes are not directly clinically tested or proven, but research shows meal replacements, in general, can help reduce caloric intake. So, how good is SlimFast for weight loss? It’s likely as effective as other options that offer protein, fiber and vitamins in a shake (or snacks/foods).
How much do Slim Fast diet shakes cost?
Slim Fast diet shakes costs typically ranges from around $5 to more than $15, depending on the SlimFast products and quantities.
Where to buy SlimFast?
SlimFast products are available in various retail stores like Walmart, CVS, Kmart and Walgreens. You can also find it in some convenience stores, according to SlimFast reviews.
How many times can I drink SlimFast in a day?
SlimFast meal replacement shakes are suggested twice daily when following the diet plan. However, depending on your caloric needs, this may be different for you. Ultimately, the idea is to burn more calories than you take in to lose weight.
How do you make SlimFast?
Many of the SlimFast products are ready-to-eat/drink. But, there are some powders out there that can be mixed with water, juice or milk. To reduce the total number of calories, you can use almond, soy or coconut milk with your SlimFast meal replacement shakes.
Is there gluten in Slim Fast?
The description for SlimFast meal replacement shakes say they are gluten-free. We didn’t see the same claim in any information on the snacks and other foods.
What does SlimFast taste like?
Some SlimFast reviews claim the meal replacements taste a little gritty or powdery. However, there are an equal number of reviews talking about how good SlimFast products taste – so it looks like it’s 50/50.
What flavors does Slim Fast have?
As of early 2017, Slim Fast meal replacement shakes were available in Creamy Chocolate, Vanilla Cream, Strawberries & Cream, Caramel Latte and Mocha Cappuccino.
Can I take SlimFast if I have a health condition?
As with any meal replacement or weight-loss supplement, you should consult your doctor before using SlimFast, especially if you are pregnant, under 18 years of age, nursing, or suffering from any health condition.
What do users like about SlimFast results?
SlimFast customers enjoy the weight-loss results with regular use.
What do users NOT like about SlimFast results?
Some customers of SlimFast do not like the bad taste and it caused indigestion, according to reviews.
How do I contact the Slim Fast customer service department?
You can call SlimFast at 1-800-754-6327. They also have various social media platforms you can contact them through.
What flavors does SlimFast have?
SlimFast meal replacement shakes are offered in Creamy Chocolate, Strawberries and Cream, Vanilla Cream, and Caramel Latte.
Do they offer other products like Slim Fast diet pills?
SlimFast as a brand does offer other products, including snacks, smoothies, and bars, but we couldn’t find anything about Slim Fast diet pills.
Does SlimFast come with a guarantee?
SlimFast may come with a guarantee, depending on the policies of the retailer it is sold at.
Do you know of any special deals or discounts on SlimFast?
No special deals or discounts are available for SlimFast. If you are looking for a great deal on a great weight-loss supplement, you may want to give Leptigen’s Special Trial Offer a try. Customers love the results and the ingredients, something that is important to us. Click here to check it out.
SlimFast Scientific Abstracts:
Soy protein consumption was linked with changes in serum LDL cholesterol levels of -0.23 mmol/l (95% confidence interval, -0.28 to -0.18 mmol/l) or a decrease (5.5%) in comparable research and -0.16 mmol/l (95% confidence interval, -0.22 to -0.11 mmol/l) or a decrease (4.2%) with crossover studies (p < 0.001 parallel versus crossover). Net serum HDL cholesterol levels were 3.2% greater (p < 0.007) in parallel studies with soy in comparison to control. Fasting serum triacylglycerol levels were lower (10.7%) for soy in comparison to control (p < 0.008). In conclusion, soy protein intake of 30 g per day was linked with substantial improvement in lipoprotein risk factors for coronary heart disease. In comparison with crossover randomized clinical trials, parallel randomized clinical trials had substantially higher quality grades and were linked with greater improvements in serum LDL cholesterol. Intake of 1 to 2 servings of soy protein every day has substantial positive effects on serum lipoprotein risk factors for cardiovascular heart disease. 
In some individuals, cognitive function quickly declined at younger ages, yet stayed intact within others until older ages. Using multivariate regression analyses, following adjustments for risk factors, the concentrations of vitamin B12 holotranscobalamin, total homocysteine, and methylmalonic acid showed a cognitive decline, while folate did not. Doubling concentrations of vitamin B12 holotranscobalamin (from 50 to 100 pmol/L) was linked with a 30% cognitive decline (−0.137 to −0.083). Doubling total homocysteine from 10 to 20 μmol/L or methylmalonic acid from 0.25 to 0.50 μmol/L was showed to have a cognitive decline of 50%. Following adjustments for every vitamin marker at the same time, the links of cognitive decline with methylmalonic acid as well as vitamin B12 holotranscobalamin remained substantial. 
Consumption of dark chocolate (cocoa products) substantially decreased serum low-density lipoprotein and total cholesterol levels (mean differences (95% confidence interval) were −5.90 mg/dl and −6.23 mg/dl. There were no statistically important effects noticed for high-density lipoprotein (mean differences (95% confidence interval): −0.76 mg/dl (−3.02 to 1.51 mg/dl)) as well as and triglyceride (−5.06 mg/dl (−13.45 to 3.32 mg/dl)). The data is consistent with the helpful traits of cocoa products on total and low-density lipoprotein cholesterol and no significant effects on high-density lipoprotein and triglyceride within short-term intervention trials. 
Before and after analysis in the group displayed substantial decreases in body mass index by 0.32 (95% confidence interval: 0.17 to 0.47; P<0.0001) as well as body fat percentage by 2.18% (95% confidence interval: 1.54 to 2.83; P<0.0001) after consumption of 30gm per day Gum Arabic for a period of 6 weeks. Participants experienced side effects of the Gum Arabic only during the first week. In conclusion, Gum Arabic was the cause of a substantial decrease in body mass index and boy fat percentage in the healthy adult females. These effects could be helpful in the treatment of obesity. 
- 1. Soy protein effects on serum lipoproteins: a quality assessment and meta-analysis of randomized, controlled studies (2011). Journal of the American College of Nutrition. January 14, 2017.
- 2. Low vitamin B-12 status and risk of cognitive decline in older adults (2007). The American Journal of Clinical Nutrition. January 14, 2017.
- 3. Effects of cocoa products/dark chocolate on serum lipids: a meta-analysis (2011). European Journal of Clinical Nutrition. January 14, 2017.
- 4. Effects of gum Arabic ingestion on body mass index and body fat percentage in healthy adult females: two-arm randomized, placebo controlled, double-blind trial (2012). Nutrition Journal. January 14, 2017.
Slim Fast meal replacements shakes and products claim to help with weight loss by helping control caloric intake.
SlimFast Ingredients and Supplement Facts
Serving Per Container:
|Amount per Serving||% DV|
|Fat free milk||*|
|Milk protein concentrate||*|
|Natural & Artificial flavors||*|
|Mono & diglycerides||*|
Other Ingredients: None
We’ve heard the ramblings about Slim Fast, so we turned our attention to Slim Fast ingredients. We will take a close look at the formula and focus on clinical research. Additionally, we’ll concentrate on hundreds of dieter comments. We’ll then summarize the info to give you the bottom line.
What You Need to Know
Slim Fast is a meal replacement containing water, milk and soy protein, sugars and vitamins, among others. Depending on the product, you consume the drink multiple times per day, which supposedly promotes weight-loss. You can bring your shake with you on the go.
The product line, introduced as a weight-loss supplement in 1977, does contain some natural ingredients, a good choice. Dieters can purchase Slim Fast through trusted retailers and at local stores. We like that the product has been around for decades and that we found some positive customer comments, but read on…
Added Sugars – Not Helping the Waistline?
The first negative about Slim Fact ingredients was added sugars. “One of the best ways to lose weight is to eliminate sugar from the diet,” said our Research Editor. “We have no idea why a dieter would want to use a product that adds it.”
“I wonder why Slim Fast can’t seem to provide a decent product that would really help dieters? This mix includes sugar as the second highest (in quantity) ingredient. Really? In a diet shake? Why? Chemical cocktail for breakfast?,” commented a dieter.
“This product contains Acesulfame which the liver cannot process, so the stuff sits on your liver and produces FORMALDEHYDE! No one should use it,” reported a customer.
In December of 2009, the Food and Drug Administration worked with Unilever relating to voluntarily recalling products due to possible contamination. The affected items were Slim Fast RTD (ready to drink) products. No further issues have arisen
According to customer reviews, Slim Fast ingredients were not as effective as promised. “High sugar, high carbs, low protein, which translates into a painfully slow weight loss. SlimFast is 10g of sugar, 2g of protein and 18 carbs! No wonder people have to keep buying this…to lose weight! It takes forever!,” reported a user.
“I started drinking it every morning starting November 1st, while adjusting my solid food intake to about 1000 calories, and I immediately plateaued. I even GAINED a pound,” commented a customer.
“Lost no weight for the months I took it. Was very careful what I ate the whole time I used Slim-fast,” said a dieter.
Throughout our research, we found that small concerns like ineffectiveness, could reduce the chances of long-term success. If Slim Fast doesn’t help you lose weight, why bother?
Based on the information on the official Slim Fast website, the products are “clinically proven”, but the company doesn’t provide links to published studies. We found information relating to sugar sweetened and artificially sweetened beverages, similar to this meal replacement. According to the American Journal of Clinical Nutrition, “Both SSB[sugar-sweetened beverage] consumption and ASB [artificially sweetened beverage] consumption were associated with increased T2D [type 2 diabetes] risk.” At DietSpotlight, finding research proving the effectiveness of items is critical. If there’s no concrete science, there are problems.
The Bottom Line
After taking a comprehensive look at Slim Fast, we’ve come to a decision. We like that the company has been offering products for decades and that we found some positive customer comments, but we can’t recommend it because there’s no published clinical research linking the ingredients to weight-loss offered up by the company. Plus, we’re concerned about added sugars and reports of the meal replacement being ineffective.
If you are looking to lose more weight, we recommend going with a supplement containing a formula supported by published clinical research with no artificial ingredients.
One of the best supplements we’ve come across in 2016 is one called Leptigen. The product contains a formula consisting of a four-ingredient proprietary blend, which has been highlighted in published scientific studies to help promote fat loss and ignite metabolism. There’s no one talking about negative side effects and from dieter reviews, people are seeing excellent results.
The makers of Leptigen are confident in the supplement, so they’re providing a Special Trial Offer, a great choice.