For anyone who has tried to lose weight one of the first questions you probably asked was “Is Slim Fast good for weight loss?” Before we answer this question let’s first determine whether you have tried to lose weight in the past. If you have I have no doubt that you heard of Slim Fast. Many people have been left wondering if Slim Fast will help you lose weight or if it is a scam. Are these statements true, or just something the marketing department made up to make their product sell?
The Slimfast of today is different than you may remember: Gone are the days of shakes alone. The original plan promises you can drop pounds with tasty snacks, meal replacements, and one sensible meal a day.
With the Slimfast plan, you eat two Slimfast meal replacements, three 100-calorie snacks (Slimfast snack bars, fruits, veggies, or even nuts), and one 500-calorie meal that you provide. With this plan you can eat 6 times per day.
The program says you can lose a safe 1 to 2 pounds per week with this strategy.
They also offer products called Slimfast Advanced Nutrition that provide high-protein meal-replacement shakes or smoothies with less sugar than many other brands. They have more protein than the original Slimfast products. The advanced plan also offers 100-calorie snacks and meal replacement bars.
What You Can Eat and What You Can’t
Meal replacements include a variety of flavors in their original and advanced protein meal bars, premade protein meal shakes, and powdered protein shake mixes (to be mixed with skim milk). In 2020, the company reformulated its drinks.
For 100-calorie snack options, choose from a variety of flavors from their original Slimfast snack bars or from the Slimfast Advanced Nutrition snacks.
For the meal you provide, Slimfast recommends filling half of your plate with vegetables (such as green beans, carrots, eggplant, spinach, or broccoli); a quarter with lean protein (beef, poultry, pork, tofu, or fish); and the remaining quarter with starch (whole wheat pasta or bread, brown rice, potatoes, or corn).
Nothing is totally off-limits with Slimfast, including alcohol. The Slimfast website features recipes for alcoholic and nonalcoholic drinks made with its shakes.
Level of Effort: Medium
You’ll need Slimfast’s snack bars, meal bars, and shakes for most of your food, but you have some flexibility for the meal that you provide.
Limitations: Slimfast’s selection of meal replacement bars and shakes is limited to about 20. You have more flexibility with snacks and with the meal you provide, which includes lean protein, vegetables, and a starch.
Cooking and shopping: Snack bars, meal replacement bars, and shakes are grab-and-go. You only plan and prepare one meal a day, which cuts down on trips to the grocery store.
Packaged foods or meals: Required.
In-person meetings: None.
Exercise: Daily exercise, including walking and strength training, is encouraged. The program doesn’t offer a specific workout plan.
Does It Allow for Dietary Restrictions or Preferences?
Vegetarians and vegans: Vegetarians can have 4 to 6 ounces of a meat alternative, such as quinoa, tofu, lentils, or black beans, for their daily meal. Reduced- or low-fat dairy (yogurt, milk, cheese) is also OK. Vegans have fewer options, since most meal replacements are made with dairy or eggs, which aren’t part of a vegan diet.
Gluten-free: The Slimfast meal-replacement shakes and smoothies are labeled gluten-free. Other products are not labeled with regard to gluten, so check the ingredients list for possible sources of gluten, and contact the company if in doubt.
Lactose-intolerant: If you have problems digesting lactose, you can combine Slimfast shake mixes with lactose-free milk or low-fat soy milk. Slimfast meal bars have 2 grams of lactose or less per serving. Slimfast Advanced Nutrition meal-replacement shakes are lactose-free.
What Else You Should Know
Cost: Slimfast products are sold in grocery stores and drugstores. Packages range from $9.99 to $89.99.
Support: You can submit questions to Slimfast’s online dietitian. Slimfast’s Facebook page offers dieters a way to connect with each other and offer advice. The Slimfast website includes meal and drink recipes, and you can sign up to get monthly emails featuring recipes, exercise and weight-loss tips, and coupons.
What Brunilda Nazario, MD, Says:
Does It Work?
Yes, Slimfast can work for weight loss. Structured programs, like this one, work for people who don’t want to count calories. Studies show that people lose more weight when they eat portion-controlled meals or meal replacements.
Low-calorie diets, such as the Slimfast diet or the use of one or two meal replacements, promote weight loss and can help you keep it off longer.
What Is the SlimFast Diet?
The SlimFast diet is a weight loss plan centered on meal-replacement shakes and snack bars formulated by the company. The shakes come in regular, low-sugar, and high-protein varieties, and the snacks are 100 calories each. The company claims that weight loss results are possible within one week.
The 2021 U.S. News and World Report Best Diets ranks the SlimFast diet number 26 in Best Diets Overall and gives it an overall score of 2.8/5. Its ranking is based on its success rate for short-term weight loss, but it received lower marks based on its nutrition content and mixed results for long-term weight loss.1
What Experts Say
“Diets that promote eating bars and shakes instead of real foods aren’t sustainable and often aren’t healthy. You might lose weight, but repla
What You Can Eat
The main focus of the SlimFast diet is the shakes, which come in a few different formulas and flavors. The newer Advanced Nutrition Shakes and Smoothies provide more protein and less carbohydrate than the original shakes.
The SlimFast Diet is centered around shakes. There are several options for what to mix in with the shake powder. Mixing the powder with water is one option, but according to SlimFast, adding unsweetened nut milk can add up to 8 grams of protein to the shakes while adding as few as 25 calories. Some options include almond milk, cashew milk, macadamia milk, and coconut milk. The nutrition information below is for the shake mix only.
Original SlimFast Chocolate Royale Shake Mix
- 110 calories
- 4 grams fat
- 18 grams carbohydrate
- 4 grams fiber
- 10 grams sugar
- 2 grams protein
Ingredients: Sugar, sunflower creamer, alkalized cocoa powder, and other ingredients.
Original SlimFast Rich Chocolate Royale Shake (Ready-to-Drink)
- 180 calories
- 5 grams fat
- 26 grams carbohydrate
- 5 grams fiber
- 19 grams sugar
- 10 grams protein
Ingredients: fat-free milk, water, sugar, cocoa, canola oil, and other ingredients.
Advanced Nutrition SlimFast Creamy Chocolate Smoothie Mix
(Before mixing with 8 ounces of skim or fat-free milk)
- 100 calories
- 3 grams fat
- 7 grams carbohydrate
- 5 grams fiber
- 1 gram sugar
- 12 grams protein
Ingredients: Whey protein isolate, soy protein isolate, cocoa, sunflower oil, and other ingredients.
The SlimFast diet allows for one “sensible” meal per day. You may consume any foods you like, as long as you stay within the caloric limits.
If you follow this diet plan, make sure your one sensible meal a day includes foods with fiber and protein.
What You Cannot Eat
No foods are explicitly banned on the SlimFast diet, but calories are restricted. You may choose to have alcohol in moderation, but SlimFast suggests limiting consumption since alcohol provides only calories and no nutrients.
How to Prepare the SlimFast Diet & Tips
If you decide to go on the SlimFast plan, you will eat six times a day: Three meals and three snacks. Two meals are replaced with a SlimFast shake, and one meal is portion-controlled. Each snack is 100 calories.
Your non-SlimFast meal can be eaten out or cooked at home, and though no foods are restricted, you are encouraged to eat nutrient-dense foods. The meal must also be very low in calories, limited to just 500 calories for women and 800 calories for men.
You can purchase SlimFast branded snacks or make your own 100-calorie snacks at home. The 100-calorie snack packs are part of SlimFast’s Advanced Nutrition program. There are a variety of both salty and sweet snacks to choose from.
According to SlimFast, women on the diet consume approximately 1,200 calories per day on the plan, and men consume 1,600 calories per day. The company claims this allows for a reasonable rate of weight loss of about 1 to 2 pounds per week. However, some people may find that they’re not getting enough daily calories, and replacing meals with shakes is not a very satiating way to eat.
When you compare the ingredients and nutrition for SlimFast products with a smoothie you make at home with fresh fruit, fiber-rich nuts and seeds, and other nutritious ingredients, you may find that DIY smoothies are a healthier choice. It would be unusual to add artificial sweeteners and thickening agents to typical smoothie recipes.
cing your meals with highly processed meal replacements won’t deliver long-lasting, satiating results.”
Does SlimFast Work?
SlimFast is a popular type of portion-controlled diet plan that involves replacing two meals per day with meal-replacement shakes, smoothies, and bars. SlimFast also has specific keto and diabetic weight loss plans. It allows for three snacks per day in addition to meals and meal replacements, chosen from SlimFast products or a list of approved 100-calorie snacks such as fruit, air-popped popcorn, or Greek yogurt.
There is one meal per day prepared by the dieter that is allowed on the SlimFast plan, though there are specific guidelines to follow on which foods to include and which foods to avoid for the meals.
Overall, the SlimFast plan works by restricting calories. In general, women will consume about 1,200 calories per day on SlimFast, while men will consume about 1,600.
Studies have shown that meal replacement diet plans such as SlimFast can be effective ways to lose weight.
Advantages of SlimFast:
- It is easy to follow because SlimFast products make up a large part of the plan, which takes out the guesswork
- Meal replacements are high in protein, which has been shown to help keep the appetite in check
Disadvantages of SlimFast:
- It requires use of their products, which may be expensive for some people
- It focuses mainly on counting calories rather than paying attention to nutrition and healthy eating habits, so it may not be the healthiest diet plan
- Dieters may gain weight once they stop following the plan
How Quickly Will You See Results on SlimFast?
SlimFast says this on their website: “Give us a week, and we’ll take off the weight.” (1) That’s a big promise, and their promotional materials say that you can lose up to 5 pounds (lb) in that first week in their Quick Start program. While that does sound exciting, experts suggest exercising caution.
“Sometimes people on meal replacement plans like this see immediate results because the diet is a shock to the body. You may be losing a bit of fat at the time, but it’s more likely water weight initially,” says Amy Goodson, RD, of Dallas–Fort Worth. The catch is, the rate of loss will slow down or eventually stop, she says — you just can’t keep it up. It’s important to know that ahead of time so that you don’t get frustrated about something so normal and common. After the initial weight loss, you may lose 1 to 2 lb per week, a number that is more sustainable.
Can You Drink Coffee While on the SlimFast Diet?
The ideal beverage to choose on SlimFast (beyond the shakes) is water. But you can also drink tea and coffee on SlimFast. The company points out that a cup of black coffee contains 1 calorie, making it a waistline-friendly sip. If you do opt for coffee, avoid adding any type of sweetener, as the company notes that sugar-sweetened beverages will stall weight loss. It’s possible to have a latte or cappuccino (what they call a “milky” coffee), but order it with skim milk, take it without sugar or flavored syrups, and count it as one of your snacks. If you’re craving java, you can also have SlimCafe, their line of on-the-go coffee drinks.
SlimFast Product Options and Foods You Can Eat on the Diet
During the majority of the day, you will be eating SlimFast products. These include meal replacement shakes, bars, and cookies, as well as snack options. SlimFast offers these foods in several different categories, depending on what version of the diet you’re on. These include:
SlimFast Original Ready-to-drink shakes and shake mixes in five flavors (like Strawberries & Cream and Cappuccino Delight) have 10 grams (g) of protein, 5 g of fiber, and vitamins and minerals to potentially “control hunger for up to four hours,” according to SlimFast.
SlimFast Keto This is their newest line. These meal replacement products are low on carbs and high on “healthy” fats, so you can “become a fat-burning machine.” For instance, their meal shake includes whey protein and collagen protein with grass-fed butter and MCTs (medium chain triglycerides). Peanut Butter Fat Bombs look like peanut butter cups, and they also have MCT oil, which is a supplement to help you stay in ketosis.
SlimFast Diabetic Weight Loss These meal replacement shake mixes are an option for those who have type 2 diabetes.
SlimFast Advanced Energy This meal replacement shake and smoothie mix contains 20 g of protein, 5 g of fiber, 1 g of sugar, and caffeine.
SlimFast Advanced Nutrition The idea is that the 20 g of protein and 1 g of sugar in this shake and smoothie mix will reduce your appetite. Available in Creamy Chocolate, Strawberries & Cream, and Vanilla Cream.
Snacks Under 200 Calories
Bake Shop While shakes may be the most recognizable part of SlimFast, you can also opt for meal replacement cookies and bars, which have between 10 and 15 g of protein and 5 g of fiber.
SlimCafe These high-protein, no-added-sugar coffee drinks contain 120 calories.
Snacks SlimFast has high-fiber 100-calorie snack packs, including chips (Sour Cream and Onion and Mesquite BBQ), crisps (Cinnamon Bun Swirl and S’Mores), and candy-like snacks (Peanut Butter Chocolate Bites). The company recommends having one of these snacks between meals.
Foods You Supply The only fresh foods you’ll need to buy and prepare will be for the one “sensible” meal and one snack per day. The sensible meal is 500 calories. Your grocery list will differ week to week depending on the specific meals you’re replacing — and SlimFast also provides suggested recipes — but that list may contain:
- Canned tuna
- Salad greens
- Spaghetti squash
- Bell peppers
- Fresh mozzarella
- Cream cheese
- Ricotta cheese
- Whole grain pasta
- Unsweetened nuts