Meal Replacements Under the Spotlight

Reviewed by Dietitian, Juliette Kellow BSc RD

With summer just around the corner, it’s likely many of us will be tempted to stray from our usual sensible diet plan and instead try something a little more extreme to quickly shift those pounds.

But while ‘miracle’ pills, patches and potions abound, the number one choice for many of us are meal replacement diets. Yes, in desperate times – we’re talking two weeks until we have to bare all on the beach – many of us are prepared to survive on just one meal each evening and fill up on strawberry shakes, tomato soup and chocolate bars during the day.

What’s the theory?

As most Weight Loss Resources members know, to lose weight we need to take in fewer calories than our body needs. When this happens, we draw on our fat stores to provide us with the extra energy we require to function properly. In the long term, this means we lose fat – and as a result, the pounds drop off.

Quite simply, meal replacement products offer a way to help us control our calorie intake, without having to worry about counting them for two meals a day. Ultimately, most plans provide around 1,200-1,400 calories each day.

How do I follow it?

It couldn’t be easier! Simply pick a meal replacement brand – the most popular one is Slim Fast – and follow the instructions.

In general, you replace two meals – usually breakfast and lunch – with a meal replacement shake, soup or bar and then have a low calorie healthy meal in the evening. Slim Fast also includes ready meals if you can’t be bothered to cook yourself a meal from scratch in the evening.

Most plans also allow two to three 100-calorie snacks a day and recommend drinking six to eight glasses of water or low-calorie drinks. Some plans also provide written information on healthy living, including changing eating habits and becoming more active.

There are also more extreme types of meal replacement diets. Very low calorie diets such as Lighter Life replace all meals with shakes or bars and sometimes soups.

How much weight can I expect to lose?

As with any reduced-calorie diet, the amount of weight you’ll lose will depend on the number of calories you consume. In general, an intake of 1,200 to 1,400 calories a day, will result in a weight loss of around 1-2lb each week.

Are meal replacement products healthy?

By law, meal replacement products must provide the recommended amount of nutrients needed for good health and their composition must conform to certain standards defined by a European Directive. According to this Directive – the guidelines for which are based on research looking at the nutritional needs of dieters – meal replacement products must contain between 200 and 400 calories, at least 25 percent protein and 23 vitamins and minerals.

With regard to fibre, most products contain around 5-6g. Healthy eating guidelines recommend adults have 18g fibre daily and so two meal replacement products make a contribution to this. Most plans also recommend including fruit and veg as snacks and as part of your main meal.

Ultimately, meal replacement products are not designed to be the only source of nutrition and contrary to popular belief, they are not the same as ‘very low calorie diets’, which generally provide less than 800 calories daily and are unsuitable for most of us.

What are the pros?

Several studies have found that meal replacements are as effective as traditional calorie-counted diets in terms of helping people to lose weight in the short term. And there are some studies which suggest that meal replacements can actually help people to keep their new lower weight.

Many people also like meal replacement products because they are convenient, they take away the need to think about food during the day and they mean the calorie counting has already been done for them.

What about the cons?

One of the main problems with the research to date is that no large long-term trials have been carried out in the UK – the majority of research has been based in the USA and Germany. Meanwhile, few trials have taken place using meal replacements in ‘real-life’ situations.

Firstly, most studies have provided meal replacement products free of charge – it’s unknown whether people would be as likely to stick to the diet if they had to buy the products themselves. Secondly, most studies have used meal replacements as part of a comprehensive programme, which includes support and dietary advice from health professionals – little is known about the weight loss achieved and maintained by people who buy and use meal replacement products on their own. Finally, most studies have involved people who are overweight or obese – few have studied normal weight people with a Body Mass Index of 20-24.9, who simply want to lose a small amount of weight.

One of the other main problems with meal replacement diets is that on their own, they do little to educate people about their eating habits. While replacing high-calorie breakfasts and lunches with a shake, soup or bar will almost certainly result in weight loss, returning to poor eating habits once you stop taking the products means you will almost certainly pile the weight back on again. Most nutrition experts recognise that if meal replacement products are to be effective at keeping the weight off in the long term, it’s essential to provide education and support on healthy eating when meal replacement products are no longer used – and this isn’t always a priority for people who want a quick weight-loss ‘fix’.

Who do meal replacements suit?

According to the British Dietetic Association, meal replacement plans are considered to be a good option for people who like a simple approach to weight loss and don’t want to have to think about planning or preparing individual meals. They’re also a potentially good option for people who prefer to eat foods that are already calorie and portion controlled for them. Meanwhile, Dietitians in Obesity Management UK say they may be useful for people who have difficulty finding time to prepare meals or struggle to control or understand portion sizes.

And who won’t meal replacements suit?

Generally speaking, if you enjoy variety in your diet and like to cook, you won’t enjoy surviving on meal replacements. Many people find them boring after a while, especially as the flavours are generally limited. If you hate strawberry, chocolate and vanilla milkshakes, meal replacement diets won’t suit you!

It’s also an expensive diet to follow – most meal replacement products are quite pricey. If you’re on a tight budget, you’ll get more for your money if you buy fresh fruit and veg. Finally, if you suffer with lactose intolerance, most products won’t be suitable as they are based on skimmed milk.

Are the products suitable for people with diabetes?

Studies do support the safety of using meal replacements in people with type 2 diabetes who are overweight or obese. However, if you have diabetes, it’s essential that you consult your doctor before starting any weight loss plan, including one based on meal replacements, as your medication might need to be adjusted as a result.

Does the diet have any side effects?

None of the research published to date suggest any adverse side effects when using meal replacements. In the past, meal replacements were considered to be a quick fix that potentially led to yo-yo dieting. It was thought most people piled the weight back on once they returned to normal eating habits. However, the latest research suggests that people can maintain the weight they lose, providing they receive advice and stick to eating a healthy, balanced diet once they stop taking the products.

What do the experts say?

Although meal replacement products have been available for some time, until now most health professionals have been reluctant to recommend them to people who need to lose weight. However, thanks to a number of studies supporting their use, several major health organisations with an interest in helping the public to lose weight now suggest meal replacements are a suitable option for some people. Organisations such as the National Obesity Forum, the British Dietetic Association and Dietitians in Obesity Management UK say meal replacements offer an alternative to other more conventional dietary treatments and may prove beneficial for some people. However, they also say this is just one of a range of possible dietary treatments to help people lose weight and recommend that additional support and advice needs to be given so that people learn to change the poor eating habits that helped them pile on the pounds in the first place.

As well as cutting calories in a controlled way, many nutrition experts also think meal replacement diets are effective because they offer a structured plan and are the ultimate convenience food as they require little or no preparation or cooking. Furthermore, they take away the ‘pressure’ of deciding what to eat for two meals each day, yet still allow an element of choice for one meal.

Juliette’s verdict

There’s certainly been an about turn in the way health professionals now view meal replacement products. Nevertheless, it’s important not to get too carried away with the results of studies to date. It’s great news that research suggests meal replacements can help people lose weight and keep it off but it’s important to remember that most study participants received additional dietary advice. Plus the very fact that someone is taking part in a study can affect their levels of motivation, with the result they are more likely to be successful.

What is clear however, is that more research still needs to be done to identify the suitability and effectiveness of meal replacement diets for ‘real-life’ situations and for people who have relatively small amounts of weight to lose.

Trying meal replacements is unlikely to do you any harm. However, for them to be successful in the long term, it’s essential you learn about what constitutes a healthy, balanced diet. Meal replacements might help you lose weight, but if you go back to eating greasy fry-ups for breakfast, mayo-laden sarnies for lunch and snack constantly on crisps, chocolate and fast food, once you stop taking the products, the pounds will quickly pile back on.

It’s also worth bearing in mind that your taste buds might quickly get tired of the same old flavours with the result that you end up craving your favourite foods. And unfortunately, cravings brought on by denial can quickly result in bingeing that in turn, causes many people to ditch their dieting intentions for good.

Finally, there’s a lot to be said for getting our nutrients from food. While meal replacement products might be nutritionally balanced, there’s good evidence to suggest our bodies are better able to utilise the vitamins and minerals found naturally in food rather than those found in fortified foods.

Ultimately, you can’t get away from the fact that following a calorie-controlled diet based on a wide range of fresh foods including fruit, veg, wholegrains, low-fat dairy products and lean protein-rich foods such as lean red meat, skinless chicken, fish and eggs, is the cheapest, tastiest and most enjoyable way to lose weight healthily.

But if you still fancy trying meal replacement products, there doesn’t seem to be any reason why you shouldn’t give them a go. Nevertheless, for the best results, I suggest you use them as a kick-start to help you shift a few pounds and then switch to a longer-term healthier eating plan that allows you to enjoy eating ‘proper’ food!

Alternatively: Don't go on a diet

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