Cutting out sugary drinks better for weight loss than restricting food

What do we know already?

Obesity is a major problem in countries such as the UK and US.

In recent years, the finger has been pointed at cheap and highly calorific food such as burgers, crisps and chocolate. But what about the drinks we wash it down with? Sugary soft drinks contain a lot of sugar but no other nutrients. They don't fill you up as solid food does, but they pack a hefty calorific punch. One can of regular Coca Cola contains 139 calories. When you consider that the recommended daily calorie intake for women is just 1940 calories, you can see how cans of soft drinks could add up to weight gain.

However, there hasn't been much research looking at the effects on weight and weight loss of 'liquid calories' from drinks.

In this study, researchers looked at the drinks consumed by 800 adults taking part in a weight-loss study. The people hadn't been told specifically to change their drinks, but were aiming to reduce their calorie intake overall.

Overall calories and calories from drinks were measured from food questionnaires they completed at the start of the study, then again after 6 months and 18 months.

What does the new study say?

The people who reduced their 'liquid calories' during the course of the study lost more weight than people who didn't reduce their liquid calories. Reducing liquid calories by just one serving a day was linked to an extra weight loss of half a kilogram after 6 months.

Half a kilogram doesn't sound very much (it's about 1lb). But, calorie by calorie, reducing calorific liquids seemed more effective than reducing solid foods.

For every 100 'solid' (food) calories a day that people cut, they lost an average 0.06 kg. But for every 100 'liquid' calories they cut per day, they lost an average 0.3 kg.

When researchers looked at different types of drinks (for example, alcoholic drinks, tea and coffee with and without sugar, milk drinks) they found that only sugar-sweetened soft drinks made a significant difference to weight loss.

How reliable are the findings?

This is a fair-sized study, and the researchers tried to adjust their figures to separate out the effect of liquid calories from food and from the amount of exercise people took.

However, the study wasn't designed from the start to look at the effects of liquid calories. The study was originally designed to look at how people responded to different types of advice on losing weight. That makes these findings a bit less reliable. It would be useful to see a study focus on how much weight people could lose if they were encouraged to concentrate on cutting out sugary soft drinks specifically.

Where does the study come from?

The study was carried out by researchers at a number of US hospitals and universities, in Maryland, Alabama and Pennsylvania. It was published in the medical journal American Journal of Clinical Nutrition, owned by the American Society for Nutrition. It was supported by a number of grants from medical institutions.

What does this mean for me?

If you need to lose weight, and you drink a lot of soft drinks, that could be a good place to start. Soft drinks don't make you feel full, but they do fill you up with calories.

But be careful what you switch to. Pure fruit juice and smoothies also have a lot of sugar, even if it's not added sugar. For weight loss, unsweetened tea or coffee – or just simple water – works better.

And if you need to lose a lot of weight, changing what you drink probably won't be enough. Talk to your doctor or practice nurse if you think you need to lose a lot of weight. They'll be able to advise you.

What should I do now?

Keep an eye on how many sugary soft drinks you consume. They can lead to weight gain – not to mention being bad for your teeth.

From:

Chen L, Appel LJ, Loria C, et al. Reduction in consumption of sugar-sweetened beverages is associated with weight loss: the PREMIER trial. Am J Clin Nutr 2009;89:1–8.

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