How The SlimFast Diet Works – Pros, Cons, And A Sample Meal Plan

Written by Priyanka Sadhukhan , MSc (Nutrition), Certified Diabetes Educator

SlimFast diet is the latest, the most raved-about diet plan that has helped many people to lose weight and retain it permanently. This meal replacement diet plan was founded by S. Daniel Abraham way back in 1977 to revolutionize the world of weight loss.

The SlimFast diet plan follows the principle of three large meals with intermittent healthy snack bars to boost metabolism, curb hunger pangs, and promote satiety. The weight loss meal replacement shake mix is packed with whey protein, vitamins, and minerals. It is also low on calories and helps one achieve sustainable weight loss.

This article elaborates on the SlimFast diet. It also contains a sample diet plan, along with the pros and cons of the diet. Swipe Up!

What Is The SlimFast Diet?

The SlimFast diet is a short-term weight loss program that uses meal replacement shakes, porridges,and meal replacement bars to help one shed fat. It is simple, convenient, and easy to follow. Its basic principle is to replace one or two meals with SlimFast shakes, enjoy real healthy foods of your choice, and include 100-calorie snack bars in between meals to curb hunger pangs and promote satiety.

SlimFast includes different formulas to add variety to the diet. It has different programs based on the need – including the SlimFast Keto Shakes, SlimFast Diabetes Weight Loss Shakes, SlimFast Advanced Energy System to boost energy levels, and SlimFast Advanced Nutrition Smoothies Mix that is ideal for the low-carb diet. It also contains a SlimFast starter pack for those who want to kick start their weight loss journey. The SlimFast Advanced Vitality Pack supports metabolism, alleviates fatigue and tiredness, and helps with weight loss.

The next section helps you understand how the SlimFast diet works.

How Does The SlimFast Diet Work?

The SlimFast diet is an upgraded weight loss program that focuses on the 3-2-1 plan. The principle of this approach is to include 3 healthy SlimFast snacks, 2 healthy SlimFast shakes, and 1 healthy meal of your choice.  By replacing regular meals and snacks with the low-calorie variants, you will be able to lose weight and kick start your body’s metabolic processes (1).

On average, the SlimFast diet provides 1200 calories for women and an additional 400 calories (1600 calories) for men per day. The SlimFast diet plans six meals a day through one full meal (500 calories for women, 800 calories for men), two shakes or smoothies, and three 100-calorie snacks. This diet kick starts your metabolism, curbs hunger, and offers complete satisfaction.

SlimFast offers a variety of 7-day meal planners that can be downloaded from their website. It also has a 30-minute workout regime to suit your weight loss goals.

Can It Help With Weight Loss

If followed as per the guidance, the SlimFast diet does help with weight loss. It works by lowering one’s calorie intake and encouraging one to replace their high-calorie conventional meals with protein-rich shakes, snack bars, and porridges.

A study showed that a very low-calorie diet with restricted carbohydrates (3-10% of total calorie intake) and restricted fat helps lower body weight by 8% in the short-run (2), (3).

A study in the Journal of Nutrition showed that people on the meal replacement SlimFast diet plan lost weight effectively when compared with those on a conventional but structured diet plan (4).

A study published in the British Medical Journal compared the effectiveness of four commercial weight-loss programs in obese and overweight individuals. Dieters on the SlimFast diet plan lost an average of 6 pounds in 4 weeks, along with significant fat loss (5).

Another study showed that the SlimFast meal replacement therapy decreased body weight by 7% and reduced BMI from 40kg/m2 to 37kg/m2 over a six-month treatment period (6).

SlimFast shakes are rich in protein. One sachet of the shake contains 26 grams of protein per serving. It contains whey protein isolates for optimum supply. Studies show that a high-protein diet increases leptin sensitivity and results in significant weight loss (7).

Furthermore, one review of six studies showed that meal replacement programs like that of SlimFast result in sustainable weight loss in long-term weight management (8).

In the following section, we have listed the foods you can eat on the SlimFast diet.

Foods To Eat

The main focus of the SlimFast diet is to make meal replacement shakes a part of the major meal. You also will have healthy 100-calorie snacks that help curb hunger pangs. The SlimFast balanced diet emphasizes filling your plate with 50% of vegetables and fruits, 25% of lean protein, and the rest 25% with whole grains.

The following options will help you plan your meals:

  • Vegetables: cucumber, tomato, asparagus, spring onion, artichokes, baby corn, bean sprouts, Italian beans, cherry tomatoes, and bell peppers
  • Leafy vegetables: Spinach, kale, celery, and Swiss chard
  • Fruits: apple, banana, pear, berries, and grapes
  • Lean meats: lean cuts of poultry, beef, and bacon
  • Dairy and dairy products: low-fat yogurt, Greek yogurt, and low-fat milk
  • Legumes: chickpeas, black beans, and lentils

In addition to including these foods in your diet, you also need to avoid certain foods.

Foods To Avoid

No foods are restricted in the SlimFast diet plan. But, as it focuses on limiting your calorie intake, the following food groups must be limited or even avoided.

  • Sugar and sugary products
  • Aerated drinks or carbonated beverages
  • Processed foods
  • High-fat fried snacks
  • Baked foods
  • Alcoholic beverages

The following section includes a sample diet plan. It will help you prepare your meal within an estimated calorie budget.

A Sample SlimFast Diet Plan

Diet Plan 1

MealsFoods To Be Included
BreakfastChunky Chocolate Flavor Shake
Snacks-11 apple
LunchSummer Strawberry Milkshake
Snacks-2Cheddar Flavor Bites
DinnerSmoked mackerel+ beetroot, potato salad with 1 tsp olive oil dressing
Snacks-3SlimFast Chocolate Caramel Treat Snack Bar

 Diet Plan 2

MealsFoods To Be Included
BreakfastSlimFast Creamy Milk Chocolate Shake
Snacks-1SlimFast Sour Cream & Chive Flavor Pretzels
LunchCafe Latte Flavor Shake
Snacks-2Heavenly Chocolate Delight Snack Bar
DinnerMushroom asparagus and bacon risotto
Snacks-3SlimFast Chocolate Caramel Treat Snack Bar

 Diet Plan 3

MealsFoods To Be Included
BreakfastSlimFast Porridge
Snacks-1Cucumber and celery stick with hummus bowl
LunchSpicy barbeque chicken salsa and potato wedges
Snacks-2A small bowl of berries mix
DinnerSlimFast Chunky Chocolate Flavor Shake
Snacks-3SlimFast Cheddar Flavor Bites

 The next section shares some recipes that can add some variety to your routine. Enjoy the healthiest foods within your calorie budget.

Healthy SlimFastRecipes

1. Mediterranian Greek Salad

Mediterranian Greek Salad


Serves: 2; Prep Time: 15 min; Cooking Time: 5 min; Total Time: 20 min

  • 1 large cucumber
  • ½ cup chopped sun-dried tomatoes
  • ½ cup chopped Roma tomatoes
  • ½ cup sliced red onions
  • ½ cup crumbled feta
  • 3 tablespoons sliced black olives
  • 2 tablespoons olive oil
  • 3 tablespoons lime juice
  • ¼ teaspoon black pepper
  • Salt to taste
How To Prepare
  1. Use a vegetable peeler to shave the cucumber into thin ribbons.
  2. Toss the cucumber ribbons, Roma tomatoes, sun-dried tomatoes, feta, and black olives in a bowl.
  3. Add olive oil, lime juice, black pepper, and salt.
  4. Toss well before eating.

2. Savory Herb Whole Grain Crackers

Savory Herb Whole Grain Crackers


Serves: 6; Prep Time: 15 min; Cooking Time: 15 min; Total Time: 30 min

  • 1 cup whole wheat flour
  • 2 teaspoons sesame seeds
  • 2 teaspoons mixed herbs, like oregano and basil
How To Prepare
  1. Make a stiff dough with the ingredients and water.
  2. Roll the dough out into thin tortillas (Indian flatbreads or chapatis)and cut theminto strips.
  3. Bake at 450°F for 10-15 minutes until they are crisp.

3. Chicken Breast With Brussel Sprouts

Chicken Breast With Brussel Sprouts


Serves – 2;Prep Time – 15 min;Cooking Time – 25 min;Total Time – 40 min


  • 8 ounces boneless chicken
  • 3 teaspoons salt
  • 2 stems broccoli
  • 2 spoons olive oil
  • 2 spoons fresh lemon juice
  • ¼ spoon freshly ground pepper
  • 3 cups thinly sliced Brussels sprouts
  • 2 stalks celery
  • ¼ cup hazel stalks
  • ¼ cup flat-leaf parsley
  • 1 ounce parmesan cheese

How To Prepare

  1. Cook chicken with salt in a saucepan. Cover with water and let it boil.
  2. Let it stand for 15 minutes.
  3. Drain the chicken and let it cool aside.
  4. Remove the broccoli stems in the meantime.
  5. Whisk lemon juice, oil, celery, salt, and pepper.
  6. Add the broccoli stems and Brussels sprouts.
  7. Add hazel and parsley too.
  8. Add chicken with dressing.
  9. Divide among 4 bowls.

SlimFast Shopping List

Following a SlimFast diet plan is easy. You need to start with stocking up on SlimFast products along with other foods. We have included them below.

  • SlimFast meal replacements: SlimFast meal shakes, cookies, meal replacement bars, porridge mixes
  • Vegetables: broccoli, tomatoes, sweet potato, potato, asparagus, leafy greens, and Brussel sprouts
  • Lean meats: beef, poultry, pork, and lamb
  • Fruits: apple, pear, papaya, cantaloupe, banana, berries, and grapes
  • Dairy and dairy products: low-fat milk, cottage cheese, unsweetened nut milk, and yogurt
  • Whole grains: quinoa, steel-cut oats, brown rice, barley, and buckwheat
  • Nuts: almonds, Brazillian nuts, pistachio nuts, and pecan nuts
  • Oils: olive, avocado, and cold-pressed coconut oils

The SlimFast diet plan is simple and effective. Like every other diet plan, it does have its share of pros and cons. We will explore them in the upcoming sections.


  • The SlimFast diet plan is an effective and sustainable weight loss program. It gives results if one follows it properly. Reduction in body weight may alleviate high blood pressure, reduce cardiovascular disease risk, and help in the treatment of diabetes (8), (9),(10).
  • The SlimFast diet schedule also encourages one to exercise for at least 30 minutes a day. Studies have shown that meal replacement plans, along with a structured exercise regime, help shed pounds and improve different biochemical markers (10).


  • Over-dependence on meal replacement shakes could keep you away from natural and seasonal food sources.
  • The program is expensive to be followed over extended periods.
  • It could limit healthy cooking options.
  • There is no mention of portion control in healthy meal plans.
  • It does not mention weight maintenance plans.
  • The diet mostly focuses on restricting calories with a high-protein meal shake. It may not be suitable for people with kidney disorders, gout, etc.

Should You Try The SlimFast Diet Plan For Weight Loss?

The SlimFast diet plan is an excellent way to reduce pounds and get your body in shape. It is a simple plan that works without compromising on your meal intake. It emphasizes eating at regular intervals to boost your metabolism and curb hunger pangs – promoting sustainable weight loss. The SlimFast meal replacement diet plan easily fits into your busy schedule and gives you the exact results that you wish for. However, there is no scientific evidence on the long-term effectiveness of the SlimFast diet plan. Hence, it is recommended you check with your doctor prior.


The SlimFast meal replacement plan is an effective and easy way to shed fat. The delicious shake mix is rich in protein, low in calories and carbs, and packed with vitamins and minerals. It helps kick start your metabolism and aids in weight loss. Combine the SlimFast diet plan with healthy recipes for a sustainable approach. But before you do that, consult your health care provider.

Frequently Asked Questions

Can you drink alcohol in the SlimFast diet plan?

Yes, you may. But moderation is key.

Can I drink tea or coffee in the SlimFast diet plan?

SlimFast diet plan emphasizes on drinking a lot of water and low-calorie beverages. You may drink black coffee or green tea or black tea, as they are low on calories. But if you want to have milk coffee, ensure you go for something made from low-fat or skim milk.

Can I use water or milk alternatives when using the shake or smoothie mix?

Yes, you may use nut milk or low-fat milk as alternatives.

Is the SlimFast plan suitable for those with diabetes?

SlimFast has formulated a range of products for those with diabetes, which help manage carb and sugar intake. If your blood sugar levels are not stable and have fluctuating HbA1C levels, consult with a diabetologist and a registered nutritionist before you go with the SlimFast diet.

Can you drink diet coke on the Slimfast diet plan?

Diet coke contains zero calories but has added sugars. It is not allowed on the Slimfastdiet plan.

What meals can you eat on the SlimFast diet?

Meals that are low on calories and packed with micronutrients can be consumed on the SlimFast diet plan.

Do you gain the weight back after you are off the SlimFast diet?

SlimFast diet is a way to schedule your meals, control hunger, and achieve satiety. After you are off the SlimFast diet, if you continue to manage your meal planning in a healthy way, you will not regain the lost weight.


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  • Guo, Xiaohui et al. “Effects of a Meal Replacement on Body Composition and Metabolic Parameters among Subjects with Overweight or Obesity.” Journal of obesity vol. 2018 2837367. 26 Dec. 2018, doi:10.1155/2018/2837367
  • Strychar, Irene. “Diet in the management of weight loss.” CMAJ : Canadian Medical Association journal = journal de l’Associationmedicalecanadienne vol. 174,1 (2006): 56-63. doi:10.1503/cmaj.045037
  • Finer, Nicholas. “Low‐Calorie Diets and Sustained Weight Loss.” Wiley Online Library, John Wiley & Sons, Ltd, 17 Sept. 2012,
  • Noakes, Manny et al. “Meal replacements are as effective as structured weight-loss diets for treating obesity in adults with features of metabolic syndrome.” The Journal of nutrition vol. 134,8 (2004): 1894-9. doi:10.1093/jn/134.8.1894
  • Truby, Helen et al. “Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC “diet trials”.” BMJ (Clinical research ed.) vol. 332,7553 (2006): 1309-14. doi:10.1136/bmj.38833.411204.80
  • Huerta, S et al. “Feasibility of a partial meal replacement plan for weight loss in low-income patients.” International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity vol. 28,12 (2004): 1575-9. doi:10.1038/sj.ijo.0802792
  • Weigle, David S et al. “A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations.” The American journal of clinical nutrition vol. 82,1 (2005): 41-8. doi:10.1093/ajcn.82.1.41
  • Heymsfield, SB. “Weight Management Using a Meal Replacement Strategy: Meta and Pooling Analysis from Six Studies.” Database of Abstracts of Reviews of Effects (DARE): Quality-Assessed Reviews [Internet]., U.S. National Library of Medicine, 1 Jan. 1970,
  • Champagne, Catherine M et al. “Dietary intakes associated with successful weight loss and maintenance during the Weight Loss Maintenance trial.” Journal of the American Dietetic Association vol. 111,12 (2011): 1826-35. doi:10.1016/j.jada.2011.09.014
  • Institute of Medicine (US) Subcommittee on Military Weight Management. “Weight-Loss and Maintenance Strategies.” Weight Management: State of the Science and Opportunities for Military Programs., U.S. National Library of Medicine, 1 Jan. 1970,

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