Another new craze of 'low-carb fever' has made its way across the Atlantic, hitting the supermarket and health store shelves. Advertised as guilt-free chocolate bars - a snack that you can eat without getting fat. But are they taking the biscuit? Dawn Gay investigates

Low-carb bars, such as Carb Minders, Carb Solutions and Atkins Endulge are stacked high in Holland and Barrett, Boots and leading supermarkets. Even Nestle Rowntree have jumped on the bandwagon with their own carb-cutting versions of Kit Kat and Rolos. They join a growing market of low-carb alternatives to foods that are traditionally high in refined carbohydrates, like pasta, bread and breakfast cereal.

According to Nestle Rowntree, the low-carb bar market value has risen to £125,000 from £10,000 six months ago. Sales of Kit Kat and Rolo varieties make up about half of this market.

Carb-bars are popular with consumers looking for a tasty snack or as an alternative to a meal. Seki Tijani, a clinical nutritionist from The Nutrition Coach sees patients who consume up to three of these bars each day, often as a meal replacement. 'Everyone jumped on the Atkins bandwagon as it has done phenomenally well (the Atkins business is now worth 15 billion dollars), so manufacturers are producing their own low-carb and high protein food.'

But is this a trick or treat? As with the fat-friendly Atkins diet, the craze for low-carb is all about eliminating certain food groups rather than cutting quantity. 'It is cleverly marketed - the makers of the bars are saying that you can still have your "naughties" and they won't affect you as they are low-carb,' says Tijani. 'Dieters still want their treats but want to eat something without cheating, so when they eat these bars they feel like they are still controlling their carbohydrate intake.'

Low in carb but high in fat and protein
These bars ditch the carbohydrates, but they are actually no lower in fat than a fully-fledged chocolate bar. A meaty Mars Bar, for example, contains 11.4 grams of fat. The low-carb bars are not far behind, in fact, the Atkins Decadence and Carb Solutions brands contain more fat than a Mars Bar! This bears another close resemblance to 'Atkins New Diet Revolution' philosophy - eat fat and cut back the carbohydrates and your body will eat into your fat stores when the carb reserves get low.

This weight-loss theory is based on the fact that when carbohydrates are absorbed into the body quickly, they are higher on the glycemic index, so blood sugar levels rise and any extra is stored as fat. 'When you eat refined carbs, like white bread and pasta, your blood sugar rises quickly and the insulin kicks in. If you take out the carb, the primary source of energy, the fat will burn as the next source of fuel after the carbohydrates. This is when the body goes into ketosis, using fat as energy,' explains nutritionist Seki Tijani.

Each bar contains 20 or 30 ingredients, from soya proteins to sweeteners, emulsifiers and vegetable fats, but these ingredients don't stimulate the release of insulin and affect blood sugar.

Without carbohydrates, there is no 'real' sugar. But, does fat fill the taste gap? 'The flavours taste fake, you feel unhealthy eating them and they don't taste natural,' one of our taste testers observed. Seki Tijani says, 'Fat gives the flavour or "mouth feel" as it satisfies the taste buds. If they cut out the sugar and replace it with sweeteners, this will affect the taste, so adding more fat will trick the taste buds.'

Neil Ducray, marketing director at Nestle Rowntree, says that getting the taste right is a complex technological process. 'It's partly the sweetener. Getting the right taste profile and "mouth feel" between the caramel and chocolate in a Rolo, for example, is very hard.'

Protein is another ingredient that appears in higher quantities in many of the low-carb bars. 'Protein doesn't stimulate the insulin that causes the body to store carbs as energy and then fat,' says Tijani. Indeed the low-carb packet of Rolos has 3.7 grams of protein compared to the standard Rolos with 1.8 grams.

Kcal comparisons
When it comes to calorie (kcal) values, conventional chocolate bars and their low-carb alternatives would make a calorie-counter devotee shudder. A Mars Bar contains 294 kcal, but Carb Solutions, the 'healthy' bar is not far behind with 257 kcal and Biochem Strive and Akins Endulgence bars are both over the 200 kcal mark. But these days who counts the calories? 'It is all a bit 80s', says Tijani, 'we have moved from counting calories, as we are now a nation obsessed with carbohydrates. We pay more attention to what food ingredients are doing to the body, such as raising insulin, rather than eating less.'

The 'net carb' trap
Screaming out from the all low-carb bar packaging are the low 'net carb' values, a measurement invented by the manufacturers, which is around two or three grams. This is the key selling point for any carb-obsessed customer. The net carbs are the values that actually affect blood sugar levels and stimulate insulin - the 'impact carbohydrates'. Indigestible carbohydrates, like mannitol and sorbitol, which are artificial sweeteners, have a minimal effect on blood sugar so are not included in the net figure.

Carbing the cost
When it comes to price, at an average of £1.69 a bar, they are not a cheap snack. The two-stick low-carb Kit Kat is almost twice the price of the original Kit Kat of twice the size. Low-carb Rolos are £1.59, costing £1.09 more than the confectionary version. Seki Tijani says, 'They know people will pay for them as they have seen a niche in the market and people think they can grab a bar and get a meal's worth - it's exploitation!'

Neil Duprey, explains that the extra cost is down to the expensive sweeteners they use, 'It's because of the polydextrose. We have taken out most of the normal sugar and this is the primary replacement, which costs three times more than normal sugar.'

Tried and tested
We reviewed the top low-carb bars on the markets - see what our reviewers had to say