Are diet foods making you fat?

Your fridge is loaded with sugar-free drinks, your cupboards packed with low-fat crisps, and biscuits. So why are the scales refusing to budge, even continuing to creep up?

The answer may lie in those ‘diet’ products. In one study from Cornell University, researchers found that adults consumed around 28 per cent more calories when they ate low-fat snacks compared to full-fat ones. The reason, say researchers, is that we feel less guilty eating low-fat foods, so we let our guard down and indulge. In other words, low-fat foods give us permission to eat more.

Added to this, low-fat foods can still be high in calories. By law, a product labelled ‘low-fat’ mustn’t have more than 3g fat per 100g. But there’s no limit on the calories or sugar it can contain. A Starbucks skinny stem-ginger iced muffin, for example, contains just 4g fat, but has 397 calories and 60g of sugar – almost double the sugar of the chain’s classic blueberry muffin.

Meanwhile, lab studies reveal that low-fat foods designed to taste like full-fat ones leave us wanting more. Scientists claim that sweet or fatty tastes prepare our bodies for calories. When the calories don’t come, our bodies send messages to our brains to keep seeking food!

These findings aren’t unique to low-fat foods, either. Numerous studies have linked calorie-free diet drinks to weight gain. One study, reported at the American Diabetes Association last summer, found that elderly adults who drank two or more ‘diet’ drinks a day saw their waist grow at five times the speed of those who didn’t drink them. It’s not clear why this happens, but one thing’s for sure – diet drinks don’t stop you craving sugar.

According to scientists from Yale University, simply believing a food is low in calories or fat can affect hormone levels. When adults drank a milkshake described as ‘high-fat, high-calorie and indulgent’, levels of ghrelin (a hormone that affects satiety) dropped, helping them feel satisfied. In contrast, ghrelin levels stayed the same or even increased slightly in adults who consumed a ‘low-fat, low-calorie and guilt-free’ milkshake. In fact, both milkshakes were identical.

The solution? If you want to lose weight, opt for fresh, natural snacks and have the odd small portion of your favourite treats.

Beat the diet food traps

● Keep a food diary, as writing down all your low-fat, low-calorie snacks might help you realise you’d be better off having just one of the real thing. For example, three 100-cal chocolate bars provide 44 per cent more calories than one Flake!

● Replace diet drinks with sparkling water and fresh lemon, lime or orange juice.

● Put together your own 100-cal nutritious snacks – such as a medium banana, eight unsalted almonds, one carrot with 4tbsp tzatziki, a small pot of fromage frais or a large bowl of fruit salad.