Why ‘sugar free’ foods could actually be causing us to gain weight.

They are in thousands of products we slip into our trolleys each week, everything from diet soft drinks, yoghurts, chewing gum and toothpaste to cakes, ice creams and breakfast cereals. You’ll find them in sachets to sweeten your tea and coffee. If you pick up any product labelled ‘sugar free’, ‘reduced sugar’ or ‘low calorie’, it’s almost certain to contain them.

One of the most commonly used artificial sweeteners – found in Diet Coke, Coke Zero and Sprite Zero – is aspartame. Weight for weight it contains the same number of calories as sugar BUT it has been chemically engineered to be 200 times sweeter, which means you only need a little. But it is a relative lightweight compared to saccharin, sucralose, neotame or advantame which are respectively 300, 600, 8000 and an astonishing 37,000 times sweeter than standard white sugar.

But there is another persuasive argument for cutting out your consumption of products that contain aspartame and other artificial sweeteners – one that might surprise you. They do not do what they claim to do… help you lose weight. If diet foods contain very few kilojoules and no sugar, surely replacing a regular soft drink with a diet soft drink is a good way to reduce sugar intake and help shed some kilos?

Several large-scale studies show this not to be the case instead finding a positive link between artificial sweetener use and weight gain. The American Cancer Society conducted a survey of 78,694 women hoping to find that artificial sweeteners had a beneficial effect on weight. Instead what they found was the opposite, with an average weight gain of roughly 1kg a year. The 2008 San Antonio Heart Study followed 5158 adults over eight years and found that instead of reducing obesity, diet drinks substantially increased the risks by a mind-blowing 47 percent! In 2012 the Northern Manhattan Study found that drinking diet soda over a period of ten years was associated with a 43 percent increase in the risk of vascular events (strokes and heart attacks). The 2008 Atherosclerosis Risk in Communities Study found a 34 percent increased incidence of metabolic syndrome in diet soft drink users, consistent with data from the 2007 Framingham Heart Study which showed a 50 percent higher incidence of metabolic syndrome. In 2014 the Women’s Health Observational Study which followed 59 614 women over 9 years found a 30 percent increased risk of cardiovascular events in those drinking two or more diet drinks daily.

Even though artificial sweeteners may decrease kilojoules and sugar they still cause weight gain. Why? Because artificial sweeteners increase insulin levels. Sucralose increases insulin by 20 percent, despite the fact that it contains no sugar or kilojoules. This insulin raising effect has also been shown for other artificial sweeteners, including the ‘natural’ sweetener stevia. Despite having minimal effect on blood sugars, both aspartame and stevia raised insulin levels higher than table sugar. Kilojoule reduction is the main advantage of artificial sweeteners, but it is not kilojoules that drive weight gain – it is insulin.

Reducing dietary sugars is a good thing, but replacing them with completely artificial, manmade chemicals of uncertain safety is not good idea. Since artificial sweeteners raise insulin – there is no benefit to eating them. The bottom line is that these chemicals do not help you lose weight – and instead may actually cause you to gain it.

References
Mullee A et al. 2019, Association Between Soft Drink Consumption and Mortality in 10 European Countries, JAMA Internal Medicine.

Stellman S & Garfinkel L, 1986, Artificial sweetener use and one-year weight change among women, Preventative Medicine.

Fowler S et al. 2008, Fueling the obesity epidemic? Artificially sweetened beverage use and long-term weight gain, Obesity.

Gardener H et al. 2012, Diet soft drink consumption is associated with an increased risk of vascular events in the Northern Manhattan Study, Journal of General Internal Medicine.

Lutsey P, Steffen L, Stevens J, 2008, Dietary intake and the development of metabolic syndrome: the Atherosclerosis Risk in Communities Study, Circulation.

American College of Cardiology, 2014, Too many diet drinks may spell heart trouble for older women, study suggests, Science Daily.