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What Is the Slimfast Diet?

What Is the Slimfast Diet?

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    The Slimfast diet is a diet plan based on having one meal of your own, followed by consuming Slimfast products as meal replacements and three snacks every day — offering weight loss within one week.

    What Is the Slimfast Diet?

    Created in 1977 by Daniel Abraham, the Slimfast diet, as the name implies, is about achieving your weight loss goals quickly. Slimfast was a popular pick given its convenience and flexibility, and it was perceived as introducing an innovative approach to weight.

    Slimfast boasts weight loss results within one week. It has an easy-to-remember three-step structure, representing your one sensible meal, two replacement meals, and three snacks. Replacement meals can include Slimfast shakes, 100-calorie snacks, or bars. These products are available on the Slimfast website and in some retail stores. Slimfast began as meal replacement shakes, and over the last 40 years, it has expanded so that its diet includes keto diets and diabetes.

    No food is forbidden, as you’re free to make your favorite foods for one daily meal. They offer convenient and flavorful meal replacement bars, 100-calorie snacks, and shakes on the Slimfast plan, including strawberries, cream shakes, and whipped triple chocolate bars.

    How the Slimfast Diet Works

    The philosophy of the Slimfast plan is that by having one meal of your own, you can replace other meals with low-calorie options to reduce your caloric intake. They suggest that regular meals and snacks boost your metabolism. Additionally, their replacement meals and snacks balance protein, fiber, and fat, allowing you to feel full and resist cravings.

    Women are allocated 1,200 calories daily, while men consume 1,600. Each snack provides 100 calories, and 200 calories come from meal replacement shakes. The 500 remaining calories come from your own meal. You can choose when and what you’d like to have for this meal, allowing it to remain relatively flexible. If you’re struggling with ideas, their website offers recipes to give you some inspiration!

    If you want additional motivation and guidance, they now offer an app to help you track your progress and meal plan.


    Exercise is recommended while on this plan. They highlight that to produce the caloric deficit required for weight loss, you should exercise for around 30 minutes daily.

    The Diet Plan

    The Slimfast diet offers four plans. These are original, favorite foods, low carb, and keto. Their in-app quiz can help you determine the best option for you. Original and favorite foods provide freedom and flexibility, while low carb and keto offer more strict options.


    Their products are available online, with Slimfast meal replacements and snacks expected to cost around $50 per week. You will then provide one meal of your own choice per week, and the cost of this will vary depending on your preferences. This is a modestly priced diet to follow—you can also buy their products in bulk and save!

    Dos and Don’ts


    • Track your calories.
    • Limit, or eliminate alcohol.
    • Exercise, around 30 minutes per day.
    • Eat many vegetables, lean meats, and legumes in your main meals.


    • Consume sugary drinks, baked, or fried foods.
    • Replace all meals with shakes: make sure you maintain one regular meal a day, alongside a maximum of two shakes.

    Sample Diet Plan

    Breakfast: Slimfast Creamy Milk Chocolate Shake

    Snack: Banana

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    avocado, broccoli and vegetables on counter

    Lunch: Slimfast Rocky Road Meal Replacement Bar

    Snack: Slimfast Chocolate Snack Bar

    Dinner: Spaghetti carbonara

    Snack: Slimfast Pretzels Snack

    Health Benefits and Drawbacks



    • Meal replacement bars, shakes, and snacks are highly processed.
    • Slimfast products are high in added sugar, which may hinder weight loss and cause you to crave sugar after getting off the diet.
    • Not sustainable long term: as this diet is labeled as a quick fix, you are not expected to sustain it long term, and it does not teach healthy eating patterns to maintain once off the diet.
    • The meal plan may become repetitive: particularly if you are purchasing Slimfast products in bulk; the lack of variety can make this diet more challenging to stay motivated on
    • While studies have demonstrated significant weight loss on this diet, other diets have resulted in more significant weight loss, particularly fat loss, that is better maintained over time.

    The Bottom Line: Is the Slimfast Diet a Healthy Way to Lose Weight?

    Like any diet that restricts calories and replaces meals, the Slimfast diet approach makes the weight challenging to keep off long term. It doesn’t teach you to cook and portion healthy meals, making it a relatively unsustainable choice.

    While Slimfast products may help you achieve your weight loss goals quickly, they will hinder your ability to learn proper cooking and eating habits that build a positive relationship with food. You can not live off Slimfast meal replacements for the rest of your life, so you could benefit more from a sensible meal plan that incorporates whole foods, teaching you how to portion your own meals and listen to your body.

    Disclaimer: The information on this website is for informational purposes only. No material on this site is intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare providers with any questions you may have regarding a medical condition or treatment before undertaking a new healthcare regimen.
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