How good would it be to drink vanilla milkshakes all day AND LOSE WEIGHT! That sounds pretty perfect to me! That’s what many meal replacement programs claim you can do. But are meal replacements the secret to weight loss, or are they too good to be true? I was keen to find out.
It’s one thing to write about the science of meal replacements but, having never followed a meal replacement diet myself, I was curious to see what it would actually feel like. I didn’t want to assume (because to assume is to make and ‘ass’ out of ‘u’ and ‘me’), so the scientist in me decided to undertake a personal experiment.
Meal replacements – What are they all about?
I am sure that you have seen an ad for a meal replacement program. I am sure that you can list a few brands off the top of your head. They are every where and meal replacement programs are a multi-billion dollar industry.
Meal replacements are a mix of shakes, bars, soups and other food products which are formulated substitutes for food-based meals and snacks. According to Food Standards Australia New Zealand (FSANZ) these products are not meant to be a total dietary replacement, but some are marketed to replace the vast majority of your diet.
Most meal replacement programs follow a similar pattern:
‘Rapid’ weight loss phase. These are often Very Low Calorie Diets (VLCD) which can range from 800 – 1200 calories. The aim is to ‘kickstart’ your weight loss. Most programs with this phase require you have meal replacements for 3 meals with additional vegetables. The duration of these phases is limited (8-12 weeks) and weight loss happens quite quickly.
Ongoing weight loss phase. Most programs then progress to a higher calorie intake, which can be maintained for a longer period. These range from 1200 – 1600 calories. These phases often consist of 2 meal replacements with more whole foods including fruit, vegetables, dairy, nuts and healthy meal containing protein and carbohydrate foods.
Mantainence phase. Once you have reached your desired weight many programs offer plans to maintain weight loss through including mostly whole foods at a higher energy level. Many programs advocate continued use of meal replacements for breakfast or occasional meals.
What does the science say?
There is a lot of scientific research around the use of meal replacement and they are often used as a tool to test the effects of weight loss on our body. While there is a lot of evidence to support their use as a weight loss tool, many studies show that weight is often regained once a meal replacement program has finished. So, they appear to be very effective at achieving weight loss in the short term, but don’t always result in sustainable change.
There are some side effects of meal replacements, particularly fatigue, dizziness, headaches, nausea, diarrhoea, constipation and irregular periods. However most of these symptoms improve when you return to a higher energy, whole food diet. Meal replacement diets are mostly considered to be safe, as long as you have support from a health care professional and you are using nutritionally adequate products.
FSANZ has certain standards for meal replacement products, particularly that they must contain at least 850kJ (202 calories) and 12g of protein per serve. They must also contain at least 25% of the recommended daily intake of vitamins including vitamin A, B6, B12 , C, D and E, and minerals including zinc, magnesium, calcium and iron. Interestingly some products do not always comply with these standards and contain errors in the nutritional information panel. This is one reason it is so important to speak to a Registered Nutritionist or Accredited Practising Dietitian about the products you are using.
What did I do?
I picked one of the many weight loss programs and followed their ‘ongoing weight loss’ structure. It was approximately 1200 calories per day (5000kJ) and required me to have:
- 2 meal replacements,
- 1 serve of dairy (250ml or milk or 200g of yoghurt)
- 1 cup of cooked veg or 2 cups of salad.
- 2 pieces of fruit
- 1 serve of healthy fats (30g of nuts or ¼ of an avocado)
- A healthy dinner containing protein, grains and vegetables
What happened? (a snippet at least)
Day 1: I started my day very excited about having vanilla milk for breakfast but it was not what I expected. I really struggled to get through my first shake. How was I going to survive a week of this? The rest of the day went okay but I was really hungry by dinnertime and ended up ordering a large burger and caving in to have a beer.
Day 2: I spent my daily whole foods meal on a family BBQ and had a chocolate shake for dinner (which tasted much nicer than the vanilla). I feel that this worked a little better in managing my appetite, even though it was a little weird watching the boy eat a chicken tikka for dinner and then going to bed without a full stomach. Stayed on plan though!
Day 3: I normally wake up really excited about breakfast but when I realised all I had was a banana shake I was quite deflated. It was also a bummer having lunch with my colleagues, with their beautiful meals, and having to stick with veg sticks and a shake.
Day 4: I tried mixing it up a bit by having a bar and a soup meal replacement. The bar was better than expected, even though I had to chew it for an excessive period of time – maybe that’s how it works? By burning calories through chewing?
Day 5: It was a long work day and I came home tired and hungry. I put together my healthy dinner and it was great. But before I knew it I was eating the chocolate Easter eggs left on the bench. I stuffed it up. It was really hard not to go crazy.
Day 6: I thought I was getting used to the food volume and I wasn’t feeling so hungry all the time. But all throughout the afternoon I was finding it hard to concentrate and getting a little bit irritable. I was really looking forward to going back to a filling breakfast and lunch!
Day 7: It was the Friday of the Easter long weekend and I was heading down the coast for a few nights of camping. Over the weekend I didn’t stress about what I was eating and had cheese, crackers, wine, BBQs, fish and chips and, of course, chocolate. I got home and back on the scales.
Results?
I started the experiment at 64.2kg with 27.8% body fat. By the end of the 6th day my weight decreased to 62.8kg with 27.6%. So, even though I lost 1.4kg, my body fat percentage didn’t change much. This may mean that the weight reduction came from reducing my stores of carbohydrate and water, rather than from changes to my body composition. This is why weight can be very deceiving!
Sounds fab right? 1.4 kg in 6 days! But when I got back from my weekend away (3 days) my weight was back to 63.8 with 27.6% body fat.
What did I learn?
Okay, lets be honest, this wasn’t a perfect experiment. I didn’t stick to it 100% and it was only a week, which isn’t much time to achieve change. It’s also important to remember that this was my personal experience. It’s not gospel and it won’t necessarily be your experience.
I did learn that planning and preparation is so important, even when you’re following a diet that is pretty much laid out for you. If I didn’t have vegetables and the approved snacks packed I would get HANGRY over the course of the afternoon. I would wander aimlessly muttering about wanting to eat ALL THE THINGS (again, poor Hilary).
I found that getting to the end of the day starving hungry lead me to make poor food choices. I would then throw in the towel and start again the next day. If I were to keep going with this, I could easily imagine beating myself up becoming really disheartened by food.
The bottom line – What does it all mean?
If you can follow a meal replacement diet you will lose weight.
Whoah! Wait. Did the dietitian just say that?
Before you start ordering a program online or loading your trolley up with shakes and bars, there are 2 really important things to consider:
- Will I be able to follow it (and stay sane)?
Is this realistically going to fit into your life with family, kids and work? I found it really tough to sit down at lunch with my colleagues, while they ate their delicious meals, and I sipped away at a strawberry shake. I got hangry and bored. It is possible to work around these things, but it requires some planning and preparation.
Is it going to perpetuate a bad relationship with food? Most of these programs list foods that are allowed and foods that are off limits. Good foods and bad foods. Rules. Many of the clients I see are confused because of rules like these.
There are also, quite a few implications from fluctuating between restriction and overindulgence, both for your mind and your body. It can leave you with feelings of failure, and a lack of control but it also disrupts our metabolic hormones. Think carefully about how it will effect you and your life.
- What will I do after the program ends?
It would be near impossible to follow a meal replacement diet for the rest of your life. Let’s be honest, nobody is planning to do that. So you have to think beyond the process of losing weight and plan for what you want food and lifestyle to look like afterwards. Going back to old habits will only result in regaining the weight.
Still want to do it? … Ask for help!
It’s really important to get some guidance and support from a Registered Nutritionist or Accredited Practising Dietitian. We can help you manage a program so that it is safe and doesn’t become an ‘all or nothing’ yo-yo diet. We can also help you to think beyond the program itself. We can help you to figure out what normal eating is going to look like and help you to maintain the weight loss you achieve.
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