By Mizpah Matus B.Hlth.Sc(Hons)

slim-fastSlim Fast is a weight loss program that substitutes cooked meals with shakes and bars. The program is over 25 years old, and is currently a brand owned by Unilever.

Slim Fast has been a popular choice for weight loss with it’s huge range of weight loss shakes.

However in recent years, Unilever has struggled with declining sales – at first blaming the popularity of Atkins.

The original Slim-Fast shakes were criticized for being too high in sugar. This was rectified by replacing sugar with the artificial sweetener Splenda. The new range of Slim-Fast products are called Optima.

Slim Fast Products

The Slim Fast offerings comprise the following:

  • Optima – Shakes (Ready-to-Drink), Bars, Smoothies, and Powders
  • Original – Shakes (Ready-to-Drink), Bars, Smoothies, and Powders
  • High Protein – Shakes and Meal Bars

A typical shake (Optima Cappuccino Delight) contains the following:

  • 5g Fat
  • 24g Carbohydrate
  • 10g Protein
  • 180 Calories
  • 24 Vitamins and Minerals

Diet Plan

The diet involves replacing two main meals with Slim-Fast products. Each day will also include one “Sensible Meal”, and fruit/vegetable snacks.

A sensible meal is based around a lean protein (such as skinless chicken breast, or fish), carbohydrate (potato, rice, or whole wheat bread), and a large serving of vegetables.

Sample Meal Plan

Optima Cappuccino Shake &
1 slice frozen French toast with 1 Tbsp light syrup
1 cup grapes
Slim·Fast Optima French Vanilla Shake &
1/2 roast beef sandwich
(2 oz. Roast beef, 1 slice whole wheat bread, 1 tbsp horseradish, lettuce, tomato)
Afternoon Snack
1 apple
Chicken Veggies Grill:

  • 4 oz. Grilled chicken breast (no skin),
  • 1 small baked potato with 2 Tbsp fat-free sour cream,
  • 1 cup steamed broccoli with
    1 Tbsp Parmesan cheese

1 cup melon

One slice low fat pound cake OR Peanut Butter crunch Snack bar.

Find other healthy low Calorie recipes here.

Are Slim Fast Users Successful?

The Slim Fast diet is a sensible and workable plan, and many people find the convenience of using meal replacements outweighs other diet plans.

However, long-term, results using Slim Fast and other meal replacement diets isn’t common.

There is one study that Slim Fast cites claiming that “People who followed The Slim·Fast Plan routinely to lose and manage their weight were, on average, 33 pounds thinner after a decade as compared to a matched group from the same community who did not participate in the study. (reference: Blackburn GL. et al. Obesity Research 2003;11:A103)”



  • Noakes, M., Foster, P. R., Keogh, J. B., & Clifton, P. M. (2004). Meal replacements are as effective as structured weight-loss diets for treating obesity in adults with features of metabolic syndrome. The Journal of nutrition, 134(8), 1894-1899. link
  • Eckel, R. H. (2008). Nonsurgical management of obesity in adults. New England Journal of Medicine, 358(18), 1941-1950. link
  • Anderson, J. W. (2004). Combination approaches to weight management. Pharmacotherapy, 4, 16. link
 By Mizpah Matus B.Hlth.Sc(Hons)
Last Reviewed: October 14, 2015. Disclaimer


  1. Andrea 1 month ago

    Where do you find a list of regular foods you can eat together with the shakes and bars

  2. pani

    there used to be these slimfast bars, the traditional ones, they were the best. these are called optima now. the snak ones were great. they discontinued. i always lost weight with them and now i cant get them from anywhere. they were square sized ones with red label, says slimfast lunch and breakfast meal option ontop. lower in calorie. and i think those were the first slimfast snacks made. aaahhhhh wish i could find them. i dont like these new snacks. they have too much carb and calorie , which i dont find helpful. its just too much. !!!!!!!!

  3. Brenda

    Hi everyone. I started slim fast April 29, and so far have lost 17 pounds. And I do go out to eat at least once a week, you can’t deprive yourself. And I also only weigh myself once a month, I think it’s better that way, after that time of the month, I just feel it makes a big difference.

  4. PB

    I started the Slim Fast diet about a week ago. I work out every day at the gym for about an hour and a half to two hours, and every few days do about 45 minutes of Zumba. I’ve been doing relatively well. The one thing I’m worried about is after I reach my goal weight. I’m worried that once I stop drinking slim fast, I will gain my weight back. Once I’m at my goal weight, I will obviously make sure all of the food I eat is very healthy and sensible choices. No more junk/fast food. Will this work? I’m just so tired of feeling like a pariah because I’m overweight.
    So, if I generally eat a low calorie diet and continue exercising on a regular basis, will I be able to maintain my ideal weight?
    Thanks a lot

    • ted

      Hi PB, You’ve discovered the problem with meal replacement products. They never teach you to eat right. Why not save your money and just eat healthy calorie controlled meals now? Here’s a site that can help with eating plans and calorie calculators. Good luck! 🙂

  5. DRiley

    Just finished my first week on SlimFast 321 plan. Messed up a few days with an extra piece of chocholate or granola bar here or there but still lost 2 lbs. Haven’t increased my exercise but still managed to lose. On to week 2 this time I’ll be better. Goal 140 current 161

  6. Sarah

    Hi there, I started Slim Fast 4 days ago-I broke last night and had sweets etc but I’m back on it again today. I want to lose 16 lbs, I would like to hear from anyone else who has slipped up and got back on it.

  7. lynn

    I started this diet three ago and lost 10lbs. For coffee lovers the mocha, vanilla, and choc. taste great in your coffee and you dont have to add the extra calorie with creams or milk and sweetners.

  8. gusta

    i have been looking for slim fast coupons and without luck, i can’t find any.. Will someone help me find them please

    thank you

  9. sadie

    for those who live in the uk, there is a really good deal on slim fast products in tesco at the moment. i’m stocked up and its day one for me so wish me luck!!

  10. stacy12

    im starting the slim fast diet today! i weigh 170 lbs… im hoping to lose 60 pounds in 2-4 months… it is suprisingly filling! hope it works for all you guys!

  11. Michelle

    I am 3 days into my 4th week on slim-fast…although i am lossing its pretty slow compared to what others say they have lost. I have a shake for breakfast, a snack bar mid morning, a shake for lunch and another snack bar in the afternoon. I have a healthy dinner. Sometimes i have the recommended 3rd snack if I need it later. So far i have lost 7lbs I am not a very big person but put some pounds on when I gave up smoking over 4mths ago that I want to come off.

  12. beth

    can the slimfast 321 plan work if you go out to eat?

    • ted

      Yes, With Slimfast you are to eat one healthy meal a day so Your eating out could be that meal, but you have to choose something healthy from the restaurant .

  13. milissa

    i started slim-fast 2 weeks ago and i am almost to the 10 lbs mark i love this diet it is really easy to follow but i changed mine a little bit to fit my schedule i have a shake for breakfast a shake for dinner a snack bar or another 100 calorie snack and i eat what ever i want for dinner since i already have a slow metabolism i did not get hungry before this diet i just ate because i knew i had to in order to live and i still do not get hungry but i also do not get super full or bloated anymore

  14. Amanda

    I just started the diet today! Had a shake this morning, snack bar, and a shake for lunch and I feel full. It’s amazing! Loving it so far

  15. LaDonna

    How can I get cappiccino flavored powder mix in Slim Fast. All you have is choc, strawberry and vanilla..I won’t buy the cans since the recall….

  16. Jamie

    I used slim fast to lose weight when I had my first daughter and it worked great…well another kid and about 5 years and I am the biggest I have been about 190lbs…I was diagnosed with PCOS and from the way the Dr. described it one day I will become a Diabetic unless I lose weight, I am also trying to concieve so before it will work I need to lose some weight. I hope this works with the help of some medicine she has me on.

  17. Sharon

    Hi, am willing to try for this slim-fast diet. Is there any store here in UAE who are selling this product?