Meal replacements for weight loss

People often ask me about meal replacement shakes (Biggest Loser, Kicstart, Optifast, Celebrity Slim, Betty Baxter, Tony Ferguson, Cambridge Diet) to aid weight loss. Are they safe? How long can you use them? Are you missing out on anything?

How you buy them

Firstly some meal replacements are sold as single-portion sachets while others come in a large tin with a measuring scoop. You can make them up with water, or low-fat milk for a nicer flavour, and drink them in place of a regular meal.

Are they for you?

As a dietitian, I believe that a healthy, reduced kilojoule diet, along with regular exercise is the best long-term method for anyone wanting to lose weight. However meal replacements can play a role at the start of a new eating plan or as a replacement for one meal a day. Let's weigh up their pros and cons - as I list each, make a mental note if you can live with them or not:

Meal replacement pros

• They come in single-serve pre-packaged portions making it easy to keep on track
• You know exactly how many kilojoules/Calories you've consumed
• There's no choice so you have no opportunity to stray
• They are quick and convenient, making them handy to use at work
• They keep you out of the kitchen (or fast food court) and away from temptation.

Meal replacement cons

• They don't teach you how to make healthy choices from real food which confronts you every day
• They don't help you to learn the kilojoule/Calorie content of a normal diet
• Many are sweet tasting, encouraging a ‘sweet tooth'
• They can pall after a while - there are only so many "chocolate or vanilla shakes" you can take
• They can be expensive.

What are they made from?

Generally they're made from non-fat milk powder sweetened with sugar, fructose or stevia with a long list of added vitamins and minerals. Some have a little fibre (inulin, psyllium or guar) added so you don't get constipated and feel fuller. Some have probiotics or green tea extract or omega-3 or soy protein present so they sound more impressive. Think of them as a milk drink combined with a multi-vitamin pill!

Here's the list of ingredients for a sachet or scoop of a typical chocolate meal replacement shake powder. You'll see it's hardly 'natural' and is a long concoction of dried ingredients and added nutrients:

You simply mix a sachet or scoop of this into a glass (200-250 mL) of water in a shaker.

What's the best way to use diet shakes?

If you replace ONE meal a day (say lunch at work) and eat two balanced meals, I think this is the most practical way to use them. Nutritionally you won't lose out and a 2006 Australian study show this gives greater satisfaction and lower drop-out rates.

Should you replace three meals day? I wouldn't recommend replacing all three meals unless you're under doctor's orders - not only is it unbalanced but it gets pretty boring after a couple of days!