What Is SlimFast?
The premise of the SlimFast diet is that meal replacement products will help you lose weight, says Keri Gans, a registered dietitian nutritionist based in New York City. On the SlimFast plan, you consume two meal replacement shakes, bars, or cookies, have a sensible meal of your choice, and three 100-calorie snacks throughout the day. (1) If you’re interested in trying the ketogenic diet, you can also follow the SlimFast Keto Plan, which requires understanding the SlimFast Keto Quick-Start Guide. “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. 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. 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. (6) 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:
ChickenCanned tunaShrimpSalmonSteakSalad greensSpaghetti squashOnionsBell peppersAsparagusFresh mozzarellaCream cheeseRicotta cheeseEggsAvocadoWhole grain pastaQuinoaUnsweetened nutsHummusPopcorn
Day 1
Breakfast SlimFast Creamy Milk Chocolate Shake (For men: Add berry parfait) Snack 100-calorie SlimFast Mesquite BBQ Baked Chips Lunch SlimFast Chocolatey Peanut Butter Pie Bar (For men: Add bowl of chili) Snack 100-calorie SlimFast S’Mores Drizzled Crisps Dinner Steak tacos Snack Nuts
Day 2
Breakfast Vegetable omelet Snack SlimFast Peanut Butter Chocolate Bites Lunch SlimFast French Vanilla Shake (For men: Add beef jerky) Snack Baby carrots and hummus Dinner SlimFast Creamy Milk Chocolate Shake (For men: Add tuna salad with crackers) Snack Sour Cream & Onion Baked Chips
Day 3
Breakfast SlimFast Double Chocolate Chip Cookie (For men: Add strips of bacon) Snack Mesquite BBQ Baked Chips Lunch Salad topped with veggies and chicken Snack String cheese Dinner SlimFast French Vanilla Shake (For men: Add prosciutto wrapped mozzarella stick) Snack Cinnamon Bun Swirl Drizzled Crisps
Pros
It’s convenient. The SlimFast plan helps people track their meals and snacks, and makes it easy to reduce calories and lose weight. You don’t have to think about portioning your food yourself or making choices on a menu. It’s all done for you. “You’re grabbing a product,” says Blatner. It removes the guesswork. With the exception of watching calories and portions during the meal and snacks you choose, you don’t have to count or measure anything for two meals and two snacks during the day. There’s wiggle room. SlimFast acknowledges that you have a social life and that your diet should fit into that. That means you can choose whatever meal is going to be your “sensible” (or healthy) meal for the day, whether that’s dinner with the family or lunch with coworkers. (1) There is a good support system. People who are on the SlimFast plan can find meal plans, recipes and ideas for snacks, tips for fitness, and an online community for support at the SlimFast website. There’s even a dietitian on staff who can answer questions.
Cons
The plan doesn’t have enough real food, by some experts’ standards. With the SlimFast plan, you are not getting the benefit of having whole, natural foods in every meal and snack. “You miss out on vital nutrients found in whole foods,” says Blatner. Adds Goodson: “This diet contains a lot of highly processed food.” Some people may not feel full after eating. Not everyone can be satisfied with the SlimFast plan. “Some people may eat multiple SlimFast bars and gain weight,” says Blatner. What’s more, if you’re heavily relying on shakes, you may not feel satisfied because you’re not chewing your food. Boredom is possible. “As with any meal replacement product, it could get tiresome,” says Gans. Though you can mix up your free meal and snack to add variety, there aren’t a lot of choices when it comes to the shakes, bars, and snacks. It’s not that tasty. Aside from being potentially boring, drinking shakes or eating chips lacks flavor, says Angela Lemond, RDN, a co-owner of Lemond Nutrition in Plano and Rockwall, Texas. It can get expensive. The SlimFast plan calls for multiple daily servings of their shakes and bars. “They are more expensive than produce,” says Blatner.
Benefits
The upside to SlimFast: “It’s super easy to follow, grab-and-go for most of the day, and is better than all-out starving yourself,” says Lemond. That’s not the most resounding review, but at least the shakes are formulated to keep you as full as possible, she says.
Risks
It’s a low-calorie plan. Even when you’re trying to lose weight, your body still needs calories to stay fueled and energized — and that’s just for the basics. “If someone likes to be active, I do not recommend this diet,” says Lemond. “It will be too restrictive and it will make it difficult to function normally,” she says. If you’re set on going on SlimFast, she recommends seeing your doctor for medical supervision.
Short-Term Effects
In the short term, being on the SlimFast plan will lead to weight loss. You’re eating 1,200 or 1,600 calories (for men and women, respectively) a day. But “people who lose weight quickly often gain it back quickly,” says Goodson.
Long-Term Effects
The likelihood you’ll want to stay on the SlimFast plan for the long term is doubtful, as you’ll probably grow tired of the limited options (and flavor and textures) of the meal replacements. Even once you hit your goal weight, SlimFast advises continuing to replace one meal a day with a SlimFast shake, bar, or cookie. (8) This means that staying on SlimFast products for the long haul is built into the plan. If you haven’t learned how to create healthy meals, you may go back to eating the way you did before, which means you may regain the weight. Moreover, experts don’t know if SlimFast will help you lose weight for good. In a review of randomized controlled studies on popular commercial weight loss diets published in the Archives of Internal Medicine in April 2015, researchers found that SlimFast had “mixed” results and that more studies are needed. Weight Watchers (WW) and Jenny Craig were found to be the best commercial programs for weight loss. (9) It’s also worth noting that for some people, a super-strict plan like this may be appealing because they don’t feel like they can trust themselves around food or they feel out of control. If that’s you, you may find that talking to a skilled therapist or knowledgeable dietitian may help you address the root problem, says Goodson. On the upside, SlimFast encourages 30 minutes of daily exercise, something they call “me time.” (1) If you follow this part of the plan, you may be able to get into the habit of regular exercise, something that will serve your health for years to come. Keto is a high-fat, very low carb diet designed to help your body enter ketosis, which is a state in which you burn fat for fuel rather than carbs. On a keto diet menu, you’ll forgo high-carb foods like bread, pasta, crackers, and even many fruits, and instead eat high-fat foods like chicken thighs with skin, avocado, and olive oil. On the SlimFast Keto plan, you will replace two meals with a low-carb, high-fat SlimFast Keto meal replacement product (like a shake or meal bar), three 100-calorie SlimFast Keto snacks, and a healthy keto-friendly meal of your choice. Additional reporting by Katherine Lee.
