Are Diet Shakes the Answer to Weight Loss?

Reducing your calorie intake and exercising more is seen as the correct solution to losing weight. As we all know that’s easier said than done! Restricting your daily energy intake is certainly not easy and it is why meal replacement diet shakes have grown in popularity during recent years. Do weight loss shakes really work and more importantly are they safe? Today we take a look at this popular dieting approach.

Weight loss shakesWe all know that skipping meals and not eating for hours on end is not a long-term solution for losing weight. Not only does our will power eventually crumble but it often results in overeating, making the whole process counterproductive!

Our bodies’ response to very low calorie diets (VLCD) or starvation diets is to go into self-preservation mode and reduces our metabolism to preserve energy, the human body as we know it took several million years of evolution to get where it is know and it’s only in roughly the last 0.00001% of that time that we’ve had food just round the corner. We’ve evolved to survive, if we start starving then we our bodies go into survival mode, which is all good if you are actually stuck in the Wild’s of Alaska but not good if you’re just dieting.

Diet shakes can be effective for some people when starting a strict diet or weight loss programme though. They help to control calorie intake and make calorie counting easier. Consuming shakes as a meal replacement ensures you don’t skip meals as well!

So are diet shakes the answer to kick starting your weight loss programme or just another dieting fad?

The Pros and Cons of Diet Shakes


  • Easy to keep an eye on your calorie intake without weighing everything
  • Ensures you don’t miss out on meals especially if you have a hectic lifestyle!
  • Can be a healthy choice providing protein and other nutrients (Many diet shakes have Vitamins and Minerals added


  • Not designed for those who need to lose a lot of weight, such as greater than 20% of their body weight
  • Not an easy weight loss solution and relies on us resisting temptation to snacks
  • They can be expensive
  • There can be side effects that include, hunger, fatigue and disturbing bowel complaints
  • Common for people to gain weight (and more) after resuming a typical diet

A Brief History of Diet Shakes

Meal replacements first started as a solution to providing nutrients and sufficient calories to astronauts whilst in space.

Slim Fast LabelIt was during the late 1970’s when the first commercial meal replacements were available being the famous “Slim Fast” diet shake introduced by Thompson Medical Company founded by S. Daniel Abraham in 1940.

Now owned by Unilever, the Slim Fast shakes were incredibly popular during the 80’s and 90’s available in a number of flavours (chocolate, vanilla and strawberry) but struggled when low-carb diets were introduced at the start of 2002.

Unilever re-branded their Slim Fast range and offered a new product range including meal replacement bars, snack bars, soups, pasta and shakes.

A variety of shakes promoting weight loss and optimal protein are now available on the market, let’s take a look at the modern day shake!

Weight Loss Diet Shakes at a Glance

Diet shakes have certainly moved on from the days of the space race with meal replacements taking a variety of forms. Available in a wide range of flavours from the standard strawberry and banana to more exotic flavour shakes such as coconut and choc cookie!

The idea behind diet shakes is to replace one or two of your meals, typically breakfast and lunch, with a shake as a replacement these typically contains around 200 calories. You are recommended to prepare and eat one healthy meal yourself which is most often your evening meal. No foods are off limits but you are advised to stick to lean proteins, fruits and vegetables for best results.

Weight loss shakes are big business with a number of well known brands on the shelves of local supermarkets, as well as advertised in magazines and the TV.

Can I Really Lose Weight with Meal Replacement Shakes?

The principle behind diet shakes is to control your portion size and therefore control and reduce the number of calories you consume each day. Diet plans that employ the use of shakes, such as Slim Fast, report weight loss of 10% of your body weight in 6 months, which works out to be around 1 to 2 pounds per week, which is seen as the safe way of losing those pounds..

It’s not a rapid weight loss approach but is a safe and healthy method that a number of health professionals suggest could work for many people.

Certainly using meal replacement shakes can help to remove the guess work out of counting calories. But with any diet plan you need determination as well as control and focus to ensure you stick to the diet shakes and not to snack out on unhealthy foods.

So how many calories are in diet shakes?

Diet shakes often contain around 200 – 250 calories per serving. So by consuming two shakes per day, one for breakfast and for one lunch, you are consuming around 600 calories from the diet shakes per day.

Take into account the healthy meal in the evening consisting of around 600 calories and a few low calorie snacks during the day, following a meal replacement diet plan provides around 1,200 -1,400 calories per day.

Are there Side Effects with Diet Shakes?

Some consumers have reported problems when trying meal replacement shakes as their chosen diet plan. Below are some of the complaints:

  • Tiredness and fatigue: There are fewer calories in meal replacement shakes which can drastically cut down on your calorie intake. This can be great to reduce calorie intake to help promote weight loss but may cause lethargy/tiredness and fatigue if you are used to consuming much more calories, especially if you aren’t active.
  • Constant hunger: Meal replacement shakes only contain around 200 calories per serving, a lot less than eating even a small meal and usually contain little fiber or fat. Unlike eating proper meals, shakes are quick to consume as you don’t need to chew any food and contains no bulk to help your stomach feel full. This means that you can often feel hungry again very soon after finishing their diet shake.
  • Digestive and bowel issues: The lack of fiber intake by consuming one or two meal replacement shakes during the day instead of meals containing more fiber and roughage may cause irregular bowel movements, diarrhoea or even constipation.

Do Meal Replacement Shakes Provide a Balanced Diet?

Although meal replacement diet plans are designed to be low calorie diets they still provide more than 1,000 calories per day. This means they are not “very low calorie diet” (VLCD) plans, which are not regards to be healthy and suitable for most people.

There are European guidelines that stipulate what must be provided in diet shakes to ensure essential nutrients are consumed. So meal replacement products must contain between 200 and 400 calories, at least 25 percent protein and 23 vitamins and minerals.

What tends to be lacking in many meal replacement products is fiber, which falls short of the daily recommended amount. This is why such diet plans will recommend having fruit and vegetables to ensure you get enough fiber in your diet.

Are Diet Shakes Recommended for Everyone?

The simple answer is no. Pregnant or breast feeding women are not recommended to take diet shakes.

If you are lactose intolerant then you need to be aware that most diet shakes contain milk.

What are the Most Popular Diet Shakes?

There are a number of diet shakes and meal replacement brands on the market; the most popular in the UK is without doubt Slim Fast, closely followed by Tony Ferguson.

Other diet plan manufacturers, such as Atkins and Jenny Craig also include meal replacement shakes too. Let’s take a quick look at Slim Fast and Tony Ferguson, where you can buy the shakes and the monthly cost.

Slim Fast

Slim FastThe first meal replacement diet shake to be commercially available (see history above), with widespread exposure in the UK and available in many high street stores such as Boots, Superdrug, Asda, Tesco and Waitrose, was Slim Fast and they now dominate the diet shake market in the UK.

Their latest range called The Slim Fast 3-2-1 Plan is their “meal replacement plan” that offers an easier way to control calorie intake without forsaking essential nutrients.

Slim Fast 123 range varies in cost according to which product you buy, a single 325ml bottle diet milkshake costs around $2.20 (£1.59). One months’ supply could cost $125 (£80), based on a minimum of two shakes per day.

Tony Ferguson

Tony FergusonDeveloped by Australian pharmacist Tony Ferguson it has been Australia’s #1 weight loss programme, the Tony Ferguson range of products is available exclusively from Boots UK.

The shakes and soups in the Tony Ferguson range replace breakfast and lunch are designed to provide 50% carbohydrates, 30% proteins and 20% essential fats and nutrients.

Tony Ferguson Multipack – 4 week supply costs around $150 (£93).

Conclusion: Weight Loss Shakes or Diet Pills?

Very few diet pills offer the range of vitamins and nutrients supplied in most diet shakes, unless you opt for fruit diet pills containing a variety of superfoods. Shakes are also ideal meal replacements as you wouldn’t wish to only take a pill for breakfast or lunch!

That said diet shakes do not increase calorie burning, but act to reduce calorie intake. They can be expensive depending upon the brand and require strong motivation and determination to succeed.

Like diet pills, meal replacement shakes do work for many people and can help weight loss. Unfortunately once the weight has come off many people go back to their usual eating habits and often put the weight back on again.

Whether you opt for shakes or pills will be somewhat a matter of preference as both can be effective. Just be aware that following a meal replacement programme properly will almost certainly cost more than buying diet pills!

Diet shakes are not for everyone! If you have lots of weight to lose, lactose intolerant, suffer from food cravings, and detest the taste or are simply on a budget you may wish to consider more cost effective diet solutions.

Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.

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5 comments on 'Are Diet Shakes the Answer to Weight Loss?'

  1. Hi there, Just thought I’d let you know that there are a couple of factual errors in this article.

    I have just been put onto a Diet by my doctor- called the Newcastle diet, this is where you have three shakes a day and an evening meal consisting only of veg- no meat, eggs, fish poultry, cheese etc.

    It can control Diabetes and results in rapid weight loss.

    The original clinical tests used the Optifast brand of shakes, but since then lots of other brands have appeared including Asda & Tesco.

    The errors:
    1) I have been set the task of losing 30% of my body mass until I retake my medic and return to work, so the factoid about not for people losing 20% is contrary to current medical opinion.
    2) The most recent pack of shake mixes I bought were 30 meal sachets for £10.00, or 33p each- which is really not expensive at all, to put this into perspective 6 sachets (2 days worth) costs less than any drink you can buy from starbucks!

    Here is the link to Newcastle Universities research.

    1. The newcastle diet as it is known is good for a few weeks but it is hard. Many shakes have over 25% sugar.When a diabetic is trying to lose weight these shakes only serve to boost your sugar numbers.
      I would like to try the Ideal shake as it only has 1 gram of sugar but these are American.

  2. I have to say Surely Slim is amazing!! I am a mom of three and have had a lot of problems trying to get rid of my baby fat. I talked to a friend who told me about Surely Slim and ordered it for me. I was 213 lbs on Wednesday and now 7 days later I am at 204 lbs. I have never had results like this with anything! You have to try it for your self you will see that it really works!

  3. I’ve been having 2 shakes a day plus lots of fruit and veg and a 600 calorie healthy evening meal for 4 days now and feel great. I’d lost 1lb after the first 2 days but haven’t weighed myself since. It’s a good way to kick start a healthy eating weight loss plan in my opinion.