Do diet drinks really make people fat?

Judith Wills / 10 April 2015

Diet and wellbeing bloger Judith Wills looks at research linking diet drinks and weight gain, and considers whether diet drinks really do make people fat.

I've never liked 'diet' calorie-free soft drinks such as cola and lemonade; in fact I've never liked fizzy drinks of any kind, other than perhaps sparkling wine of course. I've always thought if you want something that contains no calories, water does the trick every time.

The research on whether these drinks really are of any help for people trying to stay slim/lose weight over the years has been mixed, but this week the results of a relatively large long-term study on adults has found conclusively that daily intake is linked with an increase in waist circumference of an average of three inches over nine years.

This is a similar result to another much larger study carried out over eight years and concluded in 2008, consistently linking artificially sweetened drinks with higher body mass index and obesity risk.

As we know, a diet drink contains mainly water, very low-calorie artificial sweeteners and calorie-free flavourings/colourings. So if you're wondering how something that is virtually calorie-free can make you fat, let me explain.

The studies - both carried out at the University of Texas - don't actually prove that drinking diet drinks makes you fat, they merely show that people who consume them seem to get fatter than people who don't.

Although the latest study took exercise levels into account and adjusted the results accordingly, it didn't, apparently, take into account what diet-drink fanatics actually ate every day.

On the (admittedly infrequent) occasions I've found myself in a motorway cafe or a burger bar or a fast food outlet of some sort, I nosily people watch, and I've often noticed that customers who ask for the diet drink with their meal or snack are very often, very overweight.

But thinking it through, there are several possible reasons. The diet drinkers could have got fatter because they have a much sweeter than average tooth, and that could have been the reason they were drinking so much diet soda (as they call these drinks in the States) - to try to satisfy this sweet tooth. Slim people - who usually don't have much of a sweet tooth - don't need to buy the diet drinks.

Having the diet drinks also may give people a taste of something sweet, but not the satisfaction, so they then might over-indulge on other sweet stuff like cakes and desserts and chocolate.

But I think the main reason is that if you buy a diet drink, you feel you've done your bit for your waistline and your conscience, so there's no need to worry what you're going to choose for your actual meal or snack. Many a time I've sat there, in a cafe, itching to ask the person who's just bought the diet coke, but has also bought the least healthy, most calorific plate of food in the cafe - 'WHY?'

Whatever the real reason diet drinks make you fat - in my humble opinion, they aren't worth buying, unless you happen to love them and are slim. But if you're choosing them for your waist's sake or for your health - don't bother.

By the way, did you read about Clare Balding, who's managed to lose 20lbs in three months via diet and exercise? She says she was motivated to do it because of a bet with her mother. Whoever lost the most, won £100 for every pound shed. Now she doesn't say - but can we guess who won the money? I love Clare, but to say she's competitive is probably a slight understatement. She'll have researched the fact that older people take longer to lose weight, on average, than do younger people. Mum didn't stand a chance!

Ate last night: We fancied something spicy but it was too hot for a 'proper' curry, so I marinated chicken breast chunks in a mixture of Patak's tikka masala paste and natural yogurt with a dash of lime juice and plenty of chopped coriander leaf, threaded them on wooden kebab sticks, grilled them for 12 minutes, turning once or twice, and served them with half a flatbread each and a simple salad of chunky tomato, red onion and cucumber with more coriander leaf and more lime juice. Very nice, and everything healthy, too (well apart from the flatbread but who's perfect?)


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