Why I Opted Out of the Slim Fast Challenge



Whether you are fat or thin you are bound to know the one rule of losing weight: ‘eat less, move more’. It is not a difficult concept to understand but many people, including me, have trouble following it through.

As I already explained, my problem is that I love food or, more to the point and to put it bluntly, I love food and am greedy. I don’t move as much as I should in order to burn the energy I consume, and I consume far too much than I need to. I know it. I admit it. And as a consequence I am fat.

I know that I need to be better at controlling what I eat. I eat when I am bored, when I am stressed, when I am tired, or just when I fancy it. It does not matter whether I am hungry or not. I eat.

I wrote about my scepticism with regards to the Slim.Fast plan. The Slim.Fast products all contain the following information: ‘Substituting two daily meals of an energy restricted diet with meal replacements contributes to weight loss’.

It wasn’t that I didn’t believe that you could lose weight on the plan. I was quite certain that by controlling your calorie intake and upping your exercise level you would achieve some weight loss – that is the way weight loss works after all. What I was sceptical about and did concern me was whether this was actually a healthy, nutritious option. I thought that I would be able to commit to two weeks – or at the very least one week – of replacing homemade meals with substitutes, but I had not realised, or maybe just not acknowledged, the true extent of how unnatural this diet was. I accepted the challenge because I wanted to find out more.

I was keen to see what the plan involved and what I was expected to consume. I might be fat but it is all natural ingredients that made me that way. We love fresh, homemade food, barely ever have takeaways and never ready-made or convenience food. I might enjoy a cream-filled, fatty cake or lasagne but oh boy, it’ll be made from scratch with proper ingredients! I was not in the habit of consuming fake foods and I certainly wasn’t about to begin now. Would substituting unhealthy overeating of proper foods with sugar-filled, unnatural replacements have an adverse effect? I was concerned with the ingredients that actually went into creating these products.

My usual breakfast would consist of a fat free yoghurt mixed in with 30g of bran flakes or porridge. Breakfast and lunches aren’t my problem. I am content to eat healthily during the day, with this as my breakfast and a salad for lunch. My dangerous times are evenings when I pick, pick, pick at snacks, my inability to say no to pudding (‘oh, just one small slice. No, a bit bigger. Just a bit more…’), and my terrible habit of piling my dinner plate as high as I can muster.

This morning I had a Mocha flavoured shake as my replacement. The milkshake wasn’t as thick or substantial as I had expected it would be. The flavour wasn’t completely unpleasant but probably not something I would have chosen again. It wasn’t the taste of the products which concerned me but the continued selling point that replacing two meals a day would enable you to lose weight. I do not do well with denial. And if I know I am denying myself food the result is that I crave it more – whether I need it or not.

I was sent a selection of products including shakes, meal replacement bars and snacks to try. I decided to compare my usual breakfast with the Slim.Fast milkshake. Here is how they measured up:


slimfast comparison

As you can see, I have separately listed the 30g of Bran Flakes (Harvest Moon from Aldi, to be precise), and a pot of Greek Style Fat Free Lemon Yoghurt by Milbona (available from Lidl). I then added their individual figures to create a final total for my usual breakfast’s nutritional value. I then listed the nutritional values of the Slim.Fast milkshake and either a negative (red) or positive (blue) directional arrow pointing up or down indicating the increased or decreased value in comparison to my usual breakfast.

Let’s begin with the energy content. On any other morning I would have consumed a total of 188 calories with my bran and porridge breakfast. This morning, having not eaten but having only drank a liquid, I had consumed a total of 230 calories. This means I am up a total of 42 calories compared to my usual diet. Choosing a different flavour wouldn’t have made any difference to this either with Simply Vanilla, Cafe Latte, Summer Strawberry and Blissful Banana flavours all coming in with the same 962kj/230kcals per 325ml bottle. Considering that there are only 138kcal in a can of cola in comparison, it doesn’t look great.

So far, not good.

Next we will compare the fat content. My usual breakfast would have seen me consume 1g of fat – absolutely minimal at the best of times but looking even more insignificant when compared to Slim.Fast’s whopping 5.2g of fat in comparison. Wanting to give Slim.Fast the benefit of the doubt, I thought it best to check the level of saturated fat that this figure contained. It turns out that Slim.Fast’s saturated fat content is only 2g out of that 5.2g – better, but still a whole gram more than the total fat content of my usual breakfast. When compared to my usual breakfast’s saturated fat content of 0.4g however, it seems relatively fatty indeed.

Okay, let us now compare the carbs. Our bodies need carbs for energy. Carbohydrates aren’t necessarily a bad thing but they do need to be controlled. The reason for my being overweight is a limitless love of carbs and sweet treats. Cakes, breads, pasta and potatoes are my culinary delights, alas not for my figure.

My carb intake with my usual breakfast is quite a high 31.9g and, for the first time, Slim.Fast seems comparatively favourable with a lesser 28g per serving, a decrease of 3.9g. However, look a little further into carbs which sugars (this excludes starchy carbohydrates), and we’ll see that a magnificent 26g of Slim.Fast’s 28g of carbohydrates are made of up sugars. Magnificent, yes – but not in a good way, and this figure is found across the entire range of shakes too. Comparatively, my usual breakfast contains just 13.7g of sugars within its total carbohydrates of 31.9g. So where we thought Slim.Fast might have finally been more nutritious in at least one aspect, it turns out it isn’t. (For your information, a can of cola contains 35g of sugars – only 9g more than Slim.Fast’s ‘healthy’ meal alternative milkshake).

Let us see how they compare when it comes to fibre. My usual breakfast has a total of 4.7g of fibre compared to Slim.Fast’s 3.6g. Lower fibre isn’t a good thing, hence the explanation that the arrow is coloured red even though it is showing a lower figure. The fibre figure across the range of shakes is also consistent at either 3.6g or 3.9g.

Slim.Fast is still not proving itself to be a healthy alternative at all but we will press on. We will now compare protein. Here is where Slim.Fast does actually achieve a higher score than my usual bran flake and yoghurt breakfast with 15g of protein compared to my breakfast’s lower 10.2g. You would think we might be satisfied with that result but we needed more information such as, ‘how much of this protein is found naturally within the ingredients?’. Slim.Fast also fared better when it came to salt, containing just 0.4g compared to my usual’s 0.45g, with the range of shakes faring between the 0.39 and 0.42g mark.

Would my comparison have been any better if I had eaten a meal replacement bar instead of a milkshake? Let’s take a look:


slimfast comparison


As we can see, the Slim.Fast Chocolate Crunch Meal Bar does indeed score better when it comes to sugar, fibre and protein. Salt comes in with a higher content, and you’ll still be increasing your calorie and fat intake however.

Nutritional values aside, I wanted to take a closer look at the ingredients which made up my breakfast shake. Here are the ingredients that make up one ready-made bottle of milkshake:

Skimmed Milk (78%): Fairly self-explanatory there, but not sure whether it is real skimmed milk or powdered.

Coffee (6.7%): Again, real or not? And why do I feel so bad to even be questioning it?



MILK Proteins: MILK is written in CAPS. I am not sure why.

Corn Oil: An unsaturated oil extracted from the germ of corn.

Cocoa Powder (0.8%)

Stablisers (cellulose, carboxymethyl cellulose, dipotassium phospate, carrageenan): It is probably easier to decipher each of these ingredients separately so here we go:

  • Cellulose – an extract taken from wood pulp which, through processing and manufacturing, is suitable for anything from making paper to putting in our food as a thickening agent.
  • Carboxymethyl cellulose – otherwise known as E466 is another thickener used in foodstuffs. Found in many laxative remedies, it is sometimes included within a food label’s ‘dietary fibre’ figures, even though it cannot be absorbed or ingested and is incomparable to natural fibre ingredients.
  • Dipotassium phospate – a water-soluble salt used as a food additive and also within fertilisers.
  • Carrageenan – a mixture of  polysaccharides extracted from red and green seaweed used as a thickening agent in foodstuffs.

Maltodextrin: a white powder polysaccharide sugar derived from highly processed cornstarch or plants

Acacia gum: a natural gum from the acacia tree

Emulsifiers (mono and diglycerides of fatty acids) – synthetic fats produced from natural fatty acids and glycerol

Caramelised sugar

Flavourings – (no more info here than there need be)

Vitamins and minerals – magnesium oxide, vitamin C, zinc oxide, ferric pyrophosphate, vitamin E, niacin, sodium selenite, biotin, copper gluconate, manganese sulphate, vitamin A (contains SOYBEAN), vitamin B6, thiamin, vitamin D, pantothenic acid, folic acid, riboflavin

Antioxidants (sodium ascorbate, alpha-tacopherol) 

Sweeteners (sucralose, acesulfame potassium) – 

  • sucralose – a sweet synthetic compound which is up to 650 times sweeter than sugar
  • acesulfame potassium – a calorie-free sweetener. Up to 200 times sweeter than sugar and as sweet as aspartame, it is not broken down or stored by the body but absorbed and excreted.


To be fair, anything we buy will have a list of additives we don’t quite understand and, if we were to look into their meanings closer, we probably wouldn’t be very impressed with a lot of what we eat, especially when it comes to sweet treats. Having said that, reading through that ingredient list doesn’t reassure me very much that this sweet treat (or the meal replacement bars either), is a healthy replacement to a balanced meal. What this ingredient list does tell me is that this is essentially a milky coffee which has been thickened and sweetened with additives. Its ‘healthy’ aspect comes of the added vitamins and minerals it has been fortified with. There seems to be absolutely nothing of any substance which could be classed as natural or nutritious – apart from perhaps the original skimmed milk – and there is no way in the world that I can be convinced that this is a healthy alternative to a proper breakfast, lunch or dinner.

It concerns me that the onus is on replacing healthy meals with sweet, unnatural products. The high sugar factor alone is a worry; how can it be considered healthy to choose between a chocolate bar or sweetened milkshake in place of a real meal? Common sense would surely tell you that it is not healthy to substitute a proper meal for something so synthetic and highly sweetened.

I do not like to be so openly negative when it comes to reviews without weighing them up against some positives but I am struggling to find the pros of the Slim.Fast plan. I don’t want to come across as a ‘difficult’ blogger and possibly discourage companies from working with me but I do need to be truthful and, where there are normally some positives to offset the negatives when it comes to reviews, I am finding it particularly difficult in this case. Slim.Fast might claim to be successful in aiding weight loss but if one were to spend each day keeping to a limit of 1200 calories daily, they most certainly would lose weight regardless of what their meals consisted of.

Much as I would like to be able to endorse this plan positively, I am afraid that I can’t. The Slim.Fast plan just isn’t an option for long-term, healthy weight loss. Depriving myself of normal meals in favour of synthetic replacements is not a solution – not for long-term weight control or healthwise either. Eating a Slim.Fast chocolate bar in place of lunch is no different to grabbing a Mars Bar from the garage when I stop for fuel. I do like the odd chocolate, ice-cream and packet of crisps (well, quite a bit really). I am not adverse to eating junk when it comes to the sweet stuff, but there is no way I would consider replacing a meal for them and call it ‘healthy weight loss’. If I cross the calories off from my daily allowance and stick to my limit, I will lose weight whatever I have chosen to eat in place of my normal meal. But that doesn’t mean that I will have done so safely or healthily and any effects will only be for the short-term only.

I know where my problem lies – it is in me needing to change the way I think about food and to be less greedy. I need to be aware of how many calories I am consuming. I need to eat less and move more. But I don’t need Slim.Fast to take credit where it’s not due.








21 thoughts on “Why I Opted Out of the Slim Fast Challenge

  1. I have recently got a fitbit flex as part of my phone contract. I had considered getting one before but wouldn’t have actually spent the money on it. After just under a month of owning it I am completely should. Like you I prefer to eat real food, snacked too much in the evenings, and didn’t move nearly enough. The first point being the very reason I was pretty sure Slimfast wouldn’t work for you when you said the same in your blog. I’ve got the app on my phone and the competitive streak in me loves trying to meet/beat my step goal. I’ve got to grips with the food tracker on the app. My weight is going down and I am really thinking more about what I eat/do. I had been trying to give more thought to what and how I eat for a short time before getting the fitbit and it has certainly helped me build on that.

    1. I have considered getting a Fitbit to see if whether it would encourage me to be more accountable and move more, but find it hard to justify the expense for what is essentially just another gadget. Glad to hear your positive view of it though!

  2. Good luck with the weight loss! Losing weight by eating correct portions and making healthy choices is difficult. But, you will be teaching your children the proper way to achieve goals. Have you considered trying Weight Watchers? Many of my friends have found that the encouragement of a group,the portions and point system teaches them how to lose weight and keep it off long term.

    1. Thanks, Anita. I have tried WW and it did work for a time. I’m not one for group meetings though so did it online. Maybe I’ll try it again one day but I wanted to see what other options were out there first.

  3. Bran flakes only contain as many nutrients because they are fortified with “fake” ones too as are nearly all breakfast cereals so not entirely different to a slim fast meal replacement. Just for info. 🙂

    1. I did check. The foods which contain added vitamins and minerals will normally have these additions included in their ingredients list (which by law needs to state everything that has been included to make the product). This is why they are included in the ingredients list and not just the nutritional info on the Slim Fast products. Also the packaging may state ‘Fortified with… ‘. However, I have checked the ingredients on the Bran Flakes packaging which are as follow: 70% Wheat, Sugar, 15% Wheat Bran, Barley, Malt Extract, Honey, Salt. So all natural ingredients there each of which contain their own proteins and fibres which do not need to be and haven’t been added. Very different from the Slim Fast product indeed.

    1. Thank you, Izzie. The ingredients list isn’t very tempting is it? Don’t misunderstand me – there is nothing wrong with how the products taste – but they shouldn’t be considered a healthy alternative to a proper meal because they are not.

  4. The only reason I have a slimfast powder shake for breakfast is that I mix with frozen berries n ice n drink it on way to work so it’s convenient for me as I don’t like eating so early n don’t get chance to eat later.Plus bran flakes taste like cardboard to me! Xx

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